SQLite

compat

compat/*

  $(TOP)/ext/fts3/fts3_test.c  \
  $(TOP)/ext/session/test_session.c \
  $(TOP)/ext/rbu/test_rbu.c 

# Statically linked extensions
#
TESTSRC += \
  $(TOP)/ext/expert/sqlite3expert.c \
  $(TOP)/ext/expert/test_expert.c \
  $(TOP)/ext/misc/amatch.c \
  $(TOP)/ext/misc/carray.c \
  $(TOP)/ext/misc/closure.c \
  $(TOP)/ext/misc/csv.c \
  $(TOP)/ext/misc/eval.c \
  $(TOP)/ext/misc/fileio.c \
  $(TOP)/ext/misc/fuzzer.c \
  $(TOP)/ext/fts5/fts5_tcl.c \
  $(TOP)/ext/fts5/fts5_test_mi.c \
  $(TOP)/ext/fts5/fts5_test_tok.c \
  $(TOP)/ext/misc/ieee754.c \
  $(TOP)/ext/misc/mmapwarm.c \
  $(TOP)/ext/misc/nextchar.c \
  $(TOP)/ext/misc/percentile.c \
  $(TOP)/ext/misc/regexp.c \
  $(TOP)/ext/misc/remember.c \
  $(TOP)/ext/misc/series.c \
  $(TOP)/ext/misc/spellfix.c \
  $(TOP)/ext/misc/totype.c \
  $(TOP)/ext/misc/unionvtab.c \
  $(TOP)/ext/misc/wholenumber.c \
  $(TOP)/ext/misc/zipfile.c

# Source code to the library files needed by the test fixture
#
TESTSRC2 = \
  $(TOP)/src/attach.c \
  $(TOP)/src/backup.c \
  $(TOP)/src/bitvec.c \

# executables needed for testing
#
TESTPROGS = \
  testfixture$(TEXE) \
  sqlite3$(TEXE) \
  sqlite3_analyzer$(TEXE) \
  sqldiff$(TEXE) \
  dbhash$(TEXE) \
  sqltclsh$(TEXE)

# Databases containing fuzzer test cases
#
FUZZDATA = \
  $(TOP)/test/fuzzdata1.db \
  $(TOP)/test/fuzzdata2.db \
  $(TOP)/test/fuzzdata3.db \
  $(TOP)/test/fuzzdata4.db \
  $(TOP)/test/fuzzdata5.db

# Standard options to testfixture
#
TESTOPTS = --verbose=file --output=test-out.txt

# Extra compiler options for various shell tools
#
SHELL_OPT = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_FTS4
#SHELL_OPT += -DSQLITE_ENABLE_FTS5
SHELL_OPT += -DSQLITE_ENABLE_RTREE
SHELL_OPT += -DSQLITE_ENABLE_EXPLAIN_COMMENTS
SHELL_OPT += -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
SHELL_OPT += -DSQLITE_ENABLE_STMTVTAB
SHELL_OPT += -DSQLITE_ENABLE_DBPAGE_VTAB
SHELL_OPT += -DSQLITE_ENABLE_DBSTAT_VTAB
SHELL_OPT += -DSQLITE_ENABLE_OFFSET_SQL_FUNC
SHELL_OPT += -DSQLITE_INTROSPECTION_PRAGMAS
FUZZERSHELL_OPT = -DSQLITE_ENABLE_JSON1
FUZZCHECK_OPT = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_MEMSYS5 -DSQLITE_OSS_FUZZ
FUZZCHECK_OPT += -DSQLITE_MAX_MEMORY=50000000
FUZZCHECK_SRC = $(TOP)/test/fuzzcheck.c $(TOP)/test/ossfuzz.c
DBFUZZ_OPT = 

# This is the default Makefile target.  The objects listed here

keywordhash.h:	$(TOP)/tool/mkkeywordhash.c
	$(BCC) -o mkkeywordhash$(BEXE) $(OPT_FEATURE_FLAGS) $(OPTS) $(TOP)/tool/mkkeywordhash.c
	./mkkeywordhash$(BEXE) >keywordhash.h

# Source files that go into making shell.c
SHELL_SRC = \
	$(TOP)/src/shell.c.in \
        $(TOP)/ext/misc/appendvfs.c \
	$(TOP)/ext/misc/shathree.c \
	$(TOP)/ext/misc/fileio.c \
	$(TOP)/ext/misc/completion.c \
	$(TOP)/ext/misc/sqlar.c \
	$(TOP)/ext/expert/sqlite3expert.c \
	$(TOP)/ext/expert/sqlite3expert.h \
	$(TOP)/ext/misc/zipfile.c \
        $(TOP)/src/test_windirent.c

shell.c:	$(SHELL_SRC) $(TOP)/tool/mkshellc.tcl
	$(TCLSH_CMD) $(TOP)/tool/mkshellc.tcl >shell.c

	./testfixture$(TEXE) $(TOP)/test/main.test $(TESTOPTS)

sqlite3_analyzer.c: sqlite3.c $(TOP)/src/tclsqlite.c $(TOP)/tool/spaceanal.tcl $(TOP)/tool/mkccode.tcl $(TOP)/tool/sqlite3_analyzer.c.in
	$(TCLSH_CMD) $(TOP)/tool/mkccode.tcl $(TOP)/tool/sqlite3_analyzer.c.in >sqlite3_analyzer.c

sqlite3_analyzer$(TEXE): sqlite3_analyzer.c
	$(LTLINK) sqlite3_analyzer.c -o $@ $(LIBTCL) $(TLIBS)

sqltclsh.c: sqlite3.c $(TOP)/src/tclsqlite.c $(TOP)/tool/sqltclsh.tcl $(TOP)/ext/misc/appendvfs.c $(TOP)/tool/mkccode.tcl $(TOP)/tool/sqltclsh.c.in	
	$(TCLSH_CMD) $(TOP)/tool/mkccode.tcl $(TOP)/tool/sqltclsh.c.in >sqltclsh.c

sqltclsh$(TEXE): sqltclsh.c
	$(LTLINK) sqltclsh.c -o $@ $(LIBTCL) $(TLIBS)

sqlite3_expert$(TEXE): $(TOP)/ext/expert/sqlite3expert.h $(TOP)/ext/expert/sqlite3expert.c $(TOP)/ext/expert/expert.c sqlite3.c
	$(LTLINK)	$(TOP)/ext/expert/sqlite3expert.h $(TOP)/ext/expert/sqlite3expert.c $(TOP)/ext/expert/expert.c sqlite3.c -o sqlite3_expert $(TLIBS)

CHECKER_DEPS =\
  $(TOP)/tool/mkccode.tcl \
  sqlite3.c \
  $(TOP)/src/tclsqlite.c \
  $(TOP)/ext/repair/sqlite3_checker.tcl \
  $(TOP)/ext/repair/checkindex.c \

# be used for debugging with Visual Studio.
#
!IFNDEF SPLIT_AMALGAMATION
SPLIT_AMALGAMATION = 0
!ENDIF

# <<mark>>
# Set this non-0 to have this makefile assume the Tcl shell executable
# (tclsh*.exe) is available in the PATH.  By default, this is disabled
# for compatibility with older build environments.  This setting only
# applies if TCLSH_CMD is not set manually.
#
!IFNDEF USE_TCLSH_IN_PATH
USE_TCLSH_IN_PATH = 0
!ENDIF

# Set this non-0 to use zlib, possibly compiling it from source code.
#
!IFNDEF USE_ZLIB
USE_ZLIB = 0
!ENDIF

# Set this non-0 to build zlib from source code.  This is enabled by
# default and in that case it will be assumed that the ZLIBDIR macro
# points to the top-level source code directory for zlib.
#
!IFNDEF BUILD_ZLIB
BUILD_ZLIB = 1
!ENDIF

# Set this non-0 to use the International Components for Unicode (ICU).
#
!IFNDEF USE_ICU
USE_ICU = 0
!ENDIF
# <</mark>>

!IF $(DYNAMIC_SHELL)!=0 || $(FOR_WIN10)!=0
SHELL_CORE_DEP = $(SQLITE3DLL)
!ELSE
SHELL_CORE_DEP =
!ENDIF
!ENDIF

# <<mark>>
# If zlib support is enabled, add the dependencies for it.
#
!IF $(USE_ZLIB)!=0 && $(BUILD_ZLIB)!=0
SHELL_CORE_DEP = zlib $(SHELL_CORE_DEP)
TESTFIXTURE_DEP = zlib $(TESTFIXTURE_DEP)
!ENDIF
# <</mark>>

# This is the core library that the shell executable should link with.
#
!IFNDEF SHELL_CORE_LIB
!IF $(DYNAMIC_SHELL)!=0 || $(FOR_WIN10)!=0
SHELL_CORE_LIB = $(SQLITE3LIB)
!ELSE
SHELL_CORE_LIB =

# <<mark>>
# The locations of the Tcl header and library files.  Also, the library that
# non-stubs enabled programs using Tcl must link against.  These variables
# (TCLINCDIR, TCLLIBDIR, and LIBTCL) may be overridden via the environment
# prior to running nmake in order to match the actual installed location and
# version on this machine.
#
!IFNDEF TCLDIR
TCLDIR = $(TOP)\compat\tcl
!ENDIF

!IFNDEF TCLINCDIR
TCLINCDIR = $(TCLDIR)\include
!ENDIF

!IFNDEF TCLLIBDIR
TCLLIBDIR = $(TCLDIR)\lib
!ENDIF

!IFNDEF LIBTCL
LIBTCL = tcl86.lib
!ENDIF

!IFNDEF LIBTCLSTUB
LIBTCLSTUB = tclstub86.lib
!ENDIF

!IFNDEF LIBTCLPATH
LIBTCLPATH = $(TCLDIR)\bin
!ENDIF

# The locations of the zlib header and library files.  These variables
# (ZLIBINCDIR, ZLIBLIBDIR, and ZLIBLIB) may be overridden via the environment
# prior to running nmake in order to match the actual installed (or source
# code) location on this machine.
#
!IFNDEF ZLIBDIR
ZLIBDIR = $(TOP)\compat\zlib
!ENDIF

!IFNDEF ZLIBINCDIR
ZLIBINCDIR = $(ZLIBDIR)
!ENDIF

!IFNDEF ZLIBLIBDIR
ZLIBLIBDIR = $(ZLIBDIR)
!ENDIF

!IFNDEF ZLIBLIB
!IF $(DYNAMIC_SHELL)!=0
ZLIBLIB = zdll.lib
!ELSE
ZLIBLIB = zlib.lib
!ENDIF
!ENDIF

# The locations of the ICU header and library files.  These variables
# (ICUINCDIR, ICULIBDIR, and LIBICU) may be overridden via the environment
# prior to running nmake in order to match the actual installed location on
# this machine.
#
!IFNDEF ICUDIR
ICUDIR = $(TOP)\compat\icu
!ENDIF

!IFNDEF ICUINCDIR
ICUINCDIR = $(ICUDIR)\include
!ENDIF

!IFNDEF ICULIBDIR
ICULIBDIR = $(ICUDIR)\lib
!ENDIF

!IFNDEF LIBICU
LIBICU = icuuc.lib icuin.lib
!ENDIF

# This is the command to use for tclsh - normally just "tclsh", but we may
# know the specific version we want to use.  This variable (TCLSH_CMD) may be
# overridden via the environment prior to running nmake in order to select a
# specific Tcl shell to use.
#
!IFNDEF TCLSH_CMD
!IF $(USE_TCLSH_IN_PATH)!=0 || !EXIST("$(TCLDIR)\bin\tclsh.exe")
TCLSH_CMD = tclsh
!ELSE
TCLSH_CMD = $(TCLDIR)\bin\tclsh.exe
!ENDIF
!ENDIF
# <</mark>>

# Compiler options needed for programs that use the readline() library.
#
!IFNDEF READLINE_FLAGS
READLINE_FLAGS = -DHAVE_READLINE=0

#
!IF $(DEBUG)>1 || $(SYMBOLS)!=0
TCC = $(TCC) -Zi
BCC = $(BCC) -Zi
!ENDIF

# <<mark>>
# If zlib support is enabled, add the compiler options for it.
#
!IF $(USE_ZLIB)!=0
TCC = $(TCC) -DSQLITE_HAVE_ZLIB=1
RCC = $(RCC) -DSQLITE_HAVE_ZLIB=1
TCC = $(TCC) -I$(ZLIBINCDIR)
RCC = $(RCC) -I$(ZLIBINCDIR)
!ENDIF

# If ICU support is enabled, add the compiler options for it.
#
!IF $(USE_ICU)!=0
TCC = $(TCC) -DSQLITE_ENABLE_ICU=1
RCC = $(RCC) -DSQLITE_ENABLE_ICU=1
TCC = $(TCC) -I$(TOP)\ext\icu
RCC = $(RCC) -I$(TOP)\ext\icu

LDFLAGS = $(LDOPTS)
!ENDIF

# <<mark>>
# Start with the Tcl related linker options.
#
!IF $(NO_TCL)==0
TCLLIBPATHS = $(TCLLIBPATHS) /LIBPATH:$(TCLLIBDIR)
TCLLIBS = $(TCLLIBS) $(LIBTCL)
!ENDIF

# If zlib support is enabled, add the linker options for it.
#
!IF $(USE_ZLIB)!=0
LTLIBPATHS = $(LTLIBPATHS) /LIBPATH:$(ZLIBLIBDIR)
LTLIBS = $(LTLIBS) $(ZLIBLIB)
!ENDIF

# If ICU support is enabled, add the linker options for it.
#
!IF $(USE_ICU)!=0
LTLIBPATHS = $(LTLIBPATHS) /LIBPATH:$(ICULIBDIR)
LTLIBS = $(LTLIBS) $(LIBICU)

  $(TOP)\ext\fts3\fts3_test.c \
  $(TOP)\ext\rbu\test_rbu.c \
  $(TOP)\ext\session\test_session.c

# Statically linked extensions.
#
TESTEXT = \
  $(TOP)\ext\expert\sqlite3expert.c \
  $(TOP)\ext\expert\test_expert.c \
  $(TOP)\ext\misc\amatch.c \
  $(TOP)\ext\misc\carray.c \
  $(TOP)\ext\misc\closure.c \
  $(TOP)\ext\misc\csv.c \
  $(TOP)\ext\misc\eval.c \
  $(TOP)\ext\misc\fileio.c \
  $(TOP)\ext\misc\fuzzer.c \

  $(TOP)\ext\misc\regexp.c \
  $(TOP)\ext\misc\remember.c \
  $(TOP)\ext\misc\series.c \
  $(TOP)\ext\misc\spellfix.c \
  $(TOP)\ext\misc\totype.c \
  $(TOP)\ext\misc\unionvtab.c \
  $(TOP)\ext\misc\wholenumber.c

# If use of zlib is enabled, add the "zipfile.c" source file.
#
!IF $(USE_ZLIB)!=0
TESTEXT = $(TESTEXT) $(TOP)\ext\misc\zipfile.c
!ENDIF

# Source code to the library files needed by the test fixture
# (non-amalgamation)
#
TESTSRC2 = \
  $(SRC00) \
  $(SRC01) \

#
TESTPROGS = \
  testfixture.exe \
  $(SQLITE3EXE) \
  sqlite3_analyzer.exe \
  sqlite3_checker.exe \
  sqldiff.exe \
  dbhash.exe \
  sqltclsh.exe

# Databases containing fuzzer test cases
#
FUZZDATA = \
  $(TOP)\test\fuzzdata1.db \
  $(TOP)\test\fuzzdata2.db \
  $(TOP)\test\fuzzdata3.db \
  $(TOP)\test\fuzzdata4.db \
  $(TOP)\test\fuzzdata5.db
# <</mark>>

# Additional compiler options for the shell.  These are only effective
# when the shell is not being dynamically linked.
#
!IF $(DYNAMIC_SHELL)==0 && $(FOR_WIN10)==0
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_FTS4 -DSQLITE_ENABLE_EXPLAIN_COMMENTS -DSQLITE_ENABLE_STMTVTAB
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_DBPAGE_VTAB -DSQLITE_ENABLE_DBSTAT_VTAB
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_OFFSET_SQL_FUNC -DSQLITE_INTROSPECTION_PRAGMAS
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_RTREE
!ENDIF

# <<mark>>
# Extra compiler options for various test tools.
#
MPTESTER_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_FTS5
FUZZERSHELL_COMPILE_OPTS = -DSQLITE_ENABLE_JSON1

ALL_TCL_TARGETS =
!ENDIF
# <</mark>>

# This is the default Makefile target.  The objects listed here
# are what get build when you type just "make" with no arguments.
#
core:	dll libsqlite3.lib shell

# Targets that require the Tcl library.
#
tcl:	$(ALL_TCL_TARGETS)

# This Makefile target builds all of the standard binaries.
#
all:	core tcl

# Dynamic link library section.
#
dll:	$(SQLITE3DLL)

# Shell executable.
#

tclsqlite.lo:	$(TOP)\src\tclsqlite.c $(HDR) $(SQLITE_TCL_DEP)
	$(LTCOMPILE) $(NO_WARN) -DUSE_TCL_STUBS=1 -DBUILD_sqlite -I$(TCLINCDIR) -c $(TOP)\src\tclsqlite.c

tclsqlite-shell.lo:	$(TOP)\src\tclsqlite.c $(HDR) $(SQLITE_TCL_DEP)
	$(LTCOMPILE) $(NO_WARN) -DTCLSH -DBUILD_sqlite -I$(TCLINCDIR) -c $(TOP)\src\tclsqlite.c

tclsqlite3.exe:	tclsqlite-shell.lo $(SQLITE3C) $(SQLITE3H) $(LIBRESOBJS)
	$(LTLINK) $(SQLITE3C) /link $(LDFLAGS) $(LTLINKOPTS) $(TCLLIBPATHS) $(LTLIBPATHS) /OUT:$@ tclsqlite-shell.lo $(LIBRESOBJS) $(TCLLIBS) $(LTLIBS) $(TLIBS)

# Rules to build opcodes.c and opcodes.h
#
opcodes.c:	opcodes.h $(TOP)\tool\mkopcodec.tcl
	$(TCLSH_CMD) $(TOP)\tool\mkopcodec.tcl opcodes.h > opcodes.c

opcodes.h:	parse.h $(TOP)\src\vdbe.c $(TOP)\tool\mkopcodeh.tcl

keywordhash.h:	$(TOP)\tool\mkkeywordhash.c mkkeywordhash.exe
	.\mkkeywordhash.exe > keywordhash.h

# Source files that go into making shell.c
SHELL_SRC = \
	$(TOP)\src\shell.c.in \
        $(TOP)\ext\misc\appendvfs.c \
	$(TOP)\ext\misc\shathree.c \
	$(TOP)\ext\misc\fileio.c \
	$(TOP)\ext\misc\completion.c \
	$(TOP)\ext\expert\sqlite3expert.c \
	$(TOP)\ext\expert\sqlite3expert.h \
	$(TOP)\src\test_windirent.c

# If use of zlib is enabled, add the "zipfile.c" source file.
#
!IF $(USE_ZLIB)!=0
SHELL_SRC = $(SHELL_SRC) $(TOP)\ext\misc\sqlar.c
SHELL_SRC = $(SHELL_SRC) $(TOP)\ext\misc\zipfile.c
!ENDIF

shell.c:	$(SHELL_SRC) $(TOP)\tool\mkshellc.tcl
	$(TCLSH_CMD) $(TOP)\tool\mkshellc.tcl > shell.c

zlib:
	pushd $(ZLIBDIR) && $(MAKE) /f win32\Makefile.msc clean $(ZLIBLIB) && popd

# Rules to build the extension objects.
#
icu.lo:	$(TOP)\ext\icu\icu.c $(HDR) $(EXTHDR)
	$(LTCOMPILE) $(CORE_COMPILE_OPTS) $(NO_WARN) -DSQLITE_CORE -c $(TOP)\ext\icu\icu.c

fts2.lo:	$(TOP)\ext\fts2\fts2.c $(HDR) $(EXTHDR)

   fts5parse.c fts5parse.h \
   $(TOP)\ext\fts5\fts5_storage.c \
   $(TOP)\ext\fts5\fts5_tokenize.c \
   $(TOP)\ext\fts5\fts5_unicode2.c \
   $(TOP)\ext\fts5\fts5_varint.c \
   $(TOP)\ext\fts5\fts5_vocab.c

LSM1_SRC = \
   $(TOP)\ext\lsm1\lsm.h \
   $(TOP)\ext\lsm1\lsmInt.h \
   $(TOP)\ext\lsm1\lsm_ckpt.c \
   $(TOP)\ext\lsm1\lsm_file.c \
   $(TOP)\ext\lsm1\lsm_log.c \
   $(TOP)\ext\lsm1\lsm_main.c \
   $(TOP)\ext\lsm1\lsm_mem.c \
   $(TOP)\ext\lsm1\lsm_mutex.c \
   $(TOP)\ext\lsm1\lsm_shared.c \
   $(TOP)\ext\lsm1\lsm_sorted.c \
   $(TOP)\ext\lsm1\lsm_str.c \
   $(TOP)\ext\lsm1\lsm_tree.c \
   $(TOP)\ext\lsm1\lsm_unix.c \
   $(TOP)\ext\lsm1\lsm_varint.c \
   $(TOP)\ext\lsm1\lsm_vtab.c \
   $(TOP)\ext\lsm1\lsm_win32.c

fts5parse.c:	$(TOP)\ext\fts5\fts5parse.y lemon.exe
	copy $(TOP)\ext\fts5\fts5parse.y .
	del /Q fts5parse.h 2>NUL
	.\lemon.exe $(REQ_FEATURE_FLAGS) $(OPT_FEATURE_FLAGS) $(EXT_FEATURE_FLAGS) $(OPTS) fts5parse.y

fts5parse.h:	fts5parse.c

fts5.c:	$(FTS5_SRC)
	$(TCLSH_CMD) $(TOP)\ext\fts5\tool\mkfts5c.tcl
	copy $(TOP)\ext\fts5\fts5.h .

lsm1.c:	$(LSM1_SRC)
	$(TCLSH_CMD) $(TOP)\ext\lsm1\tool\mklsm1c.tcl
	copy $(TOP)\ext\lsm1\lsm.h .

fts5.lo:	fts5.c $(HDR) $(EXTHDR)
	$(LTCOMPILE) $(CORE_COMPILE_OPTS) $(NO_WARN) -DSQLITE_CORE -c fts5.c

fts5_ext.lo:	fts5.c $(HDR) $(EXTHDR)
	$(LTCOMPILE) $(NO_WARN) -c fts5.c

fts5.dll:	fts5_ext.lo

	type "$(TCLINCDIR)\tcl.h" | $(TCLSH_CMD) $(TOP)\tool\replace.tcl exact tclDecls.h sqlite_tclDecls.h \
		| $(TCLSH_CMD) $(TOP)\tool\replace.tcl regsub "typedef (.*?)\(Tcl_" "typedef \1 (SQLITE_TCLAPI Tcl_" \
		| $(TCLSH_CMD) $(TOP)\tool\replace.tcl exact "void (*freeProc)" "void (SQLITE_TCLAPI *freeProc)" \
		| $(TCLSH_CMD) $(TOP)\tool\replace.tcl exact "Tcl_HashEntry *(*findProc)" "Tcl_HashEntry *(SQLITE_TCLAPI *findProc)" \
		| $(TCLSH_CMD) $(TOP)\tool\replace.tcl exact "Tcl_HashEntry *(*createProc)" "Tcl_HashEntry *(SQLITE_TCLAPI *createProc)" >> $(SQLITETCLH)
!ENDIF

testfixture.exe:	$(TESTFIXTURE_SRC) $(TESTFIXTURE_DEP) $(SQLITE3H) $(LIBRESOBJS) $(HDR) $(SQLITE_TCL_DEP)
	$(LTLINK) -DSQLITE_NO_SYNC=1 $(TESTFIXTURE_FLAGS) \
		-DBUILD_sqlite -I$(TCLINCDIR) \
		$(TESTFIXTURE_SRC) \
		/link $(LDFLAGS) $(LTLINKOPTS) $(TCLLIBPATHS) $(LTLIBPATHS) $(LIBRESOBJS) $(TCLLIBS) $(LTLIBS) $(TLIBS)

extensiontest:	testfixture.exe testloadext.dll
	@set PATH=$(LIBTCLPATH);$(PATH)
	.\testfixture.exe $(TOP)\test\loadext.test $(TESTOPTS)

fulltest:	$(TESTPROGS) fuzztest
	@set PATH=$(LIBTCLPATH);$(PATH)

	.\testfixture.exe $(TOP)\test\main.test $(TESTOPTS)

sqlite3_analyzer.c:	$(SQLITE3C) $(SQLITE3H) $(TOP)\src\tclsqlite.c $(TOP)\tool\spaceanal.tcl $(TOP)\tool\mkccode.tcl $(TOP)\tool\sqlite3_analyzer.c.in $(SQLITE_TCL_DEP)
	$(TCLSH_CMD) $(TOP)\tool\mkccode.tcl $(TOP)\tool\sqlite3_analyzer.c.in > $@

sqlite3_analyzer.exe:	sqlite3_analyzer.c $(LIBRESOBJS)
	$(LTLINK) $(NO_WARN) -DBUILD_sqlite -I$(TCLINCDIR) sqlite3_analyzer.c \
		/link $(LDFLAGS) $(LTLINKOPTS) $(TCLLIBPATHS) $(LTLIBPATHS) $(LIBRESOBJS) $(TCLLIBS) $(LTLIBS) $(TLIBS)

sqltclsh.c: sqlite3.c $(TOP)\src\tclsqlite.c $(TOP)\tool\sqltclsh.tcl $(TOP)\ext\misc\appendvfs.c $(TOP)\tool\mkccode.tcl $(TOP)\tool\sqltclsh.c.in
	$(TCLSH_CMD) $(TOP)\tool\mkccode.tcl $(TOP)\tool\sqltclsh.c.in >sqltclsh.c

sqltclsh.exe: sqltclsh.c  $(SHELL_CORE_DEP) $(LIBRESOBJS)
	$(LTLINK) $(NO_WARN) -DBUILD_sqlite -I$(TCLINCDIR) sqltclsh.c \
		/link $(LDFLAGS) $(LTLINKOPTS) $(TCLLIBPATHS) $(LTLIBPATHS) $(LIBRESOBJS) $(TCLLIBS) $(LTLIBS) $(TLIBS)

sqlite3_expert.exe: $(SQLITE3C) $(TOP)\ext\expert\sqlite3expert.h $(TOP)\ext\expert\sqlite3expert.c $(TOP)\ext\expert\expert.c
	$(LTLINK) $(NO_WARN)	$(TOP)\ext\expert\sqlite3expert.c $(TOP)\ext\expert\expert.c $(SQLITE3C) $(TLIBS)

CHECKER_DEPS =\
  $(TOP)/tool/mkccode.tcl \
  sqlite3.c \
  $(TOP)/src/tclsqlite.c \
  $(TOP)/ext/repair/sqlite3_checker.tcl \
  $(TOP)/ext/repair/checkindex.c \
  $(TOP)/ext/repair/checkfreelist.c \
  $(TOP)/ext/misc/btreeinfo.c \
  $(TOP)/ext/repair/sqlite3_checker.c.in

sqlite3_checker.c:	$(CHECKER_DEPS)
	$(TCLSH_CMD) $(TOP)\tool\mkccode.tcl $(TOP)\ext\repair\sqlite3_checker.c.in > $@

sqlite3_checker.exe:	sqlite3_checker.c $(LIBRESOBJS)
	$(LTLINK) $(NO_WARN) -DBUILD_sqlite -I$(TCLINCDIR) sqlite3_checker.c \
		/link $(LDFLAGS) $(LTLINKOPTS) $(TCLLIBPATHS) $(LTLIBPATHS) $(LIBRESOBJS) $(TCLLIBS) $(LTLIBS) $(TLIBS)

dbdump.exe:	$(TOP)\ext\misc\dbdump.c $(SQLITE3C) $(SQLITE3H)
	$(LTLINK) $(NO_WARN) -DDBDUMP_STANDALONE $(TOP)\ext\misc\dbdump.c $(SQLITE3C) \
		/link $(LDFLAGS) $(LTLINKOPTS) $(LTLIBPATHS) $(LIBRESOBJS) $(LTLIBS)

testloadext.lo:	$(TOP)\src\test_loadext.c
	$(LTCOMPILE) $(NO_WARN) -c $(TOP)\src\test_loadext.c

	del /Q mptester.exe wordcount.exe rbu.exe srcck1.exe 2>NUL
	del /Q sqlite3.c sqlite3-*.c 2>NUL
	del /Q sqlite3rc.h 2>NUL
	del /Q shell.c sqlite3ext.h sqlite3session.h 2>NUL
	del /Q sqlite3_analyzer.exe sqlite3_analyzer.c 2>NUL
	del /Q sqlite-*-output.vsix 2>NUL
	del /Q fuzzershell.exe fuzzcheck.exe sqldiff.exe dbhash.exe 2>NUL
	del /Q sqltclsh.exe 2>NUL
	del /Q fts5.* fts5parse.* 2>NUL
	del /Q lsm.h lsm1.c 2>NUL
# <</mark>>

<h1 align="center">SQLite Source Repository</h1>

This repository contains the complete source code for the SQLite database
engine.  Some test scripts are also included.  However, many other test scripts
and most of the documentation are managed separately.

If you are reading this on a Git mirror someplace, you are doing it wrong.
The [official repository](https://www.sqlite.org/src/) is better.  Go there
now.

## Obtaining The Code

to the "sqlite3.dll" command line above.  When debugging into the SQLite
code, adding the "DEBUG=1" argument to one of the above command lines is
recommended.

SQLite does not require [Tcl](http://www.tcl.tk/) to run, but a Tcl installation
is required by the makefiles (including those for MSVC).  SQLite contains
a lot of generated code and Tcl is used to do much of that code generation.


## Source Code Tour

Most of the core source files are in the **src/** subdirectory.  The
**src/** folder also contains files used to build the "testfixture" test
harness. The names of the source files used by "testfixture" all begin
with "test".
The **src/** also contains the "shell.c" file
which is the main program for the "sqlite3.exe"
[command-line shell](https://sqlite.org/cli.html) and
the "tclsqlite.c" file which implements the
[Tcl bindings](https://sqlite.org/tclsqlite.html) for SQLite.
(Historical note:  SQLite began as a Tcl
extension and only later escaped to the wild as an independent library.)

Test scripts and programs are found in the **test/** subdirectory.
Addtional test code is found in other source repositories.
See [How SQLite Is Tested](http://www.sqlite.org/testing.html) for
additional information.

the src/parse.y file.  The conversion of "parse.y" into "parse.c" is done
by the [lemon](./doc/lemon.html) LALR(1) parser generator.  The source code
for lemon is at tool/lemon.c.  Lemon uses the tool/lempar.c file as a
template for generating its parser.

Lemon also generates the **parse.h** header file, at the same time it
generates parse.c. But the parse.h header file is
modified further (to add additional symbols) using the ./addopcodes.tcl
Tcl script.

The **opcodes.h** header file contains macros that define the numbers
corresponding to opcodes in the "VDBE" virtual machine.  The opcodes.h
file is generated by the scanning the src/vdbe.c source file.  The
Tcl script at ./mkopcodeh.tcl does this scan and generates opcodes.h.
A second Tcl script, ./mkopcodec.tcl, then scans opcodes.h to generate
the **opcodes.c** source file, which contains a reverse mapping from
opcode-number to opcode-name that is used for EXPLAIN output.

The **keywordhash.h** header file contains the definition of a hash table
that maps SQL language keywords (ex: "CREATE", "SELECT", "INDEX", etc.) into
the numeric codes used by the parse.c parser.  The keywordhash.h file is
generated by a C-language program at tool mkkeywordhash.c.

tool/mksqlite3c.tcl script is run to copy them all together in just the
right order while resolving internal "#include" references.

The amalgamation source file is more than 200K lines long.  Some symbolic
debuggers (most notably MSVC) are unable to deal with files longer than 64K
lines.  To work around this, a separate Tcl script, tool/split-sqlite3c.tcl,
can be run on the amalgamation to break it up into a single small C file
called **sqlite3-all.c** that does #include on about seven other files
named **sqlite3-1.c**, **sqlite3-2.c**, ..., **sqlite3-7.c**.  In this way,
all of the source code is contained within a single translation unit so
that the compiler can do extra cross-procedure optimization, but no
individual source file exceeds 32K lines in length.

## How It All Fits Together

SQLite is modular in design.

Key files:

  *  **sqlite.h.in** - This file defines the public interface to the SQLite
     library.  Readers will need to be familiar with this interface before
     trying to understand how the library works internally.

  *  **sqliteInt.h** - this header file defines many of the data objects
     used internally by SQLite.  In addition to "sqliteInt.h", some
     subsystems have their own header files.

  *  **parse.y** - This file describes the LALR(1) grammar that SQLite uses
     to parse SQL statements, and the actions that are taken at each step
     in the parsing process.

  *  **vdbe.c** - This file implements the virtual machine that runs
     prepared statements.  There are various helper files whose names
     begin with "vdbe".  The VDBE has access to the vdbeInt.h header file
     which defines internal data objects.  The rest of SQLite interacts
     with the VDBE through an interface defined by vdbe.h.

  *  **where.c** - This file (together with its helper files named
     by "where*.c") analyzes the WHERE clause and generates
     virtual machine code to run queries efficiently.  This file is
     sometimes called the "query optimizer".  It has its own private
     header file, whereInt.h, that defines data objects used internally.

  *  **btree.c** - This file contains the implementation of the B-Tree
     storage engine used by SQLite.  The interface to the rest of the system
     is defined by "btree.h".  The "btreeInt.h" header defines objects
     used internally by btree.c and not published to the rest of the system.

  *  **pager.c** - This file contains the "pager" implementation, the
     module that implements transactions.  The "pager.h" header file
     defines the interface between pager.c and the rest of the system.

  *  **os_unix.c** and **os_win.c** - These two files implement the interface
     between SQLite and the underlying operating system using the run-time
     pluggable VFS interface.

  *  **shell.c.in** - This file is not part of the core SQLite library.  This
     is the file that, when linked against sqlite3.a, generates the
     "sqlite3.exe" command-line shell.  The "shell.c.in" file is transformed
     into "shell.c" as part of the build process.

  *  **tclsqlite.c** - This file implements the Tcl bindings for SQLite.  It
     is not part of the core SQLite library.  But as most of the tests in this
     repository are written in Tcl, the Tcl language bindings are important.

  *  **test*.c** - Files in the src/ folder that begin with "test" go into
     building the "testfixture.exe" program.  The testfixture.exe program is
     an enhanced Tcl shell.  The testfixture.exe program runs scripts in the
     test/ folder to validate the core SQLite code.  The testfixture program
     (and some other test programs too) is build and run when you type
     "make test".

  *  **ext/misc/json1.c** - This file implements the various JSON functions
     that are build into SQLite.

There are many other source files.  Each has a succinct header comment that
describes its purpose and role within the larger system.


## Contacts

The main SQLite webpage is [http://www.sqlite.org/](http://www.sqlite.org/)
with geographically distributed backups at
[http://www2.sqlite.org/](http://www2.sqlite.org) and
[http://www3.sqlite.org/](http://www3.sqlite.org).

!IFNDEF SHELL_CORE_DEP
!IF $(DYNAMIC_SHELL)!=0 || $(FOR_WIN10)!=0
SHELL_CORE_DEP = $(SQLITE3DLL)
!ELSE
SHELL_CORE_DEP =
!ENDIF
!ENDIF


# This is the core library that the shell executable should link with.
#
!IFNDEF SHELL_CORE_LIB
!IF $(DYNAMIC_SHELL)!=0 || $(FOR_WIN10)!=0
SHELL_CORE_LIB = $(SQLITE3LIB)
!ELSE

# Additional compiler options for the shell.  These are only effective
# when the shell is not being dynamically linked.
#
!IF $(DYNAMIC_SHELL)==0 && $(FOR_WIN10)==0
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_JSON1 -DSQLITE_ENABLE_FTS4 -DSQLITE_ENABLE_EXPLAIN_COMMENTS -DSQLITE_ENABLE_STMTVTAB
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_DBPAGE_VTAB -DSQLITE_ENABLE_DBSTAT_VTAB
SHELL_COMPILE_OPTS = $(SHELL_COMPILE_OPTS) -DSQLITE_ENABLE_OFFSET_SQL_FUNC -DSQLITE_INTROSPECTION_PRAGMAS
!ENDIF


# This is the default Makefile target.  The objects listed here
# are what get build when you type just "make" with no arguments.
#
core:	dll shell

# Targets that require the Tcl library.
#
tcl:	$(ALL_TCL_TARGETS)

# This Makefile target builds all of the standard binaries.
#
all:	core tcl

# Dynamic link library section.
#
dll:	$(SQLITE3DLL)

# Shell executable.
#

## SQLite Expert Extension

This folder contains code for a simple system to propose useful indexes
given a database and a set of SQL queries. It works as follows:

  1. The user database schema is copied to a temporary database.

  1. All SQL queries are prepared against the temporary database.
     Information regarding the WHERE and ORDER BY clauses, and other query
     features that affect index selection are recorded.

  1. The information gathered in step 2 is used to create candidate 
     indexes - indexes that the planner might have made use of in the previous
     step, had they been available.

  1. A subset of the data in the user database is used to generate statistics
     for all existing indexes and the candidate indexes generated in step 3
     above.

  1. The SQL queries are prepared a second time. If the planner uses any
     of the indexes created in step 3, they are recommended to the user.

# C API

The SQLite expert C API is defined in sqlite3expert.h. Most uses will proceed
as follows:

  1. An sqlite3expert object is created by calling **sqlite3\_expert\_new()**.
     A database handle opened by the user is passed as an argument.

  1. The sqlite3expert object is configured with one or more SQL statements
     by making one or more calls to **sqlite3\_expert\_sql()**. Each call may
     specify a single SQL statement, or multiple statements separated by
     semi-colons.
  
  1. Optionally, the **sqlite3\_expert\_config()** API may be used to 
     configure the size of the data subset used to generate index statistics.
     Using a smaller subset of the data can speed up the analysis.

  1. **sqlite3\_expert\_analyze()** is called to run the analysis.

  1. One or more calls are made to **sqlite3\_expert\_report()** to extract
     components of the results of the analysis.

  1. **sqlite3\_expert\_destroy()** is called to free all resources.

Refer to comments in sqlite3expert.h for further details.

# sqlite3_expert application

The file "expert.c" contains the code for a command line application that
uses the API described above. It can be compiled with (for example):

<pre>
  gcc -O2 sqlite3.c expert.c sqlite3expert.c -o sqlite3_expert
</pre>

Assuming the database is named "test.db", it can then be run to analyze a
single query:

<pre>
  ./sqlite3_expert -sql &lt;sql-query&gt; test.db
</pre>

Or an entire text file worth of queries with:

<pre>
  ./sqlite3_expert -file &lt;text-file&gt; test.db
</pre>

By default, sqlite3\_expert generates index statistics using all the data in
the user database. For a large database, this may be prohibitively time
consuming. The "-sample" option may be used to configure sqlite3\_expert to
generate statistics based on an integer percentage of the user database as
follows:

<pre>
  # Generate statistics based on 25% of the user database rows:
  ./sqlite3_expert -sample 25 -sql &lt;sql-query&gt; test.db

  # Do not generate any statistics at all:
  ./sqlite3_expert -sample 0 -sql &lt;sql-query&gt; test.db
</pre>

/*
** 2017 April 07
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
*/


#include <sqlite3.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "sqlite3expert.h"


static void option_requires_argument(const char *zOpt){
  fprintf(stderr, "Option requires an argument: %s\n", zOpt);
  exit(-3);
}

static int option_integer_arg(const char *zVal){
  return atoi(zVal);
}

static void usage(char **argv){
  fprintf(stderr, "\n");
  fprintf(stderr, "Usage %s ?OPTIONS? DATABASE\n", argv[0]);
  fprintf(stderr, "\n");
  fprintf(stderr, "Options are:\n");
  fprintf(stderr, "  -sql SQL   (analyze SQL statements passed as argument)\n");
  fprintf(stderr, "  -file FILE (read SQL statements from file FILE)\n");
  fprintf(stderr, "  -verbose LEVEL (integer verbosity level. default 1)\n");
  fprintf(stderr, "  -sample PERCENT (percent of db to sample. default 100)\n");
  exit(-1);
}

static int readSqlFromFile(sqlite3expert *p, const char *zFile, char **pzErr){
  FILE *in = fopen(zFile, "rb");
  long nIn;
  size_t nRead;
  char *pBuf;
  int rc;
  if( in==0 ){
    *pzErr = sqlite3_mprintf("failed to open file %s\n", zFile);
    return SQLITE_ERROR;
  }
  fseek(in, 0, SEEK_END);
  nIn = ftell(in);
  rewind(in);
  pBuf = sqlite3_malloc64( nIn+1 );
  nRead = fread(pBuf, nIn, 1, in);
  fclose(in);
  if( nRead!=1 ){
    sqlite3_free(pBuf);
    *pzErr = sqlite3_mprintf("failed to read file %s\n", zFile);
    return SQLITE_ERROR;
  }
  pBuf[nIn] = 0;
  rc = sqlite3_expert_sql(p, pBuf, pzErr);
  sqlite3_free(pBuf);
  return rc;
}

int main(int argc, char **argv){
  const char *zDb;
  int rc = 0;
  char *zErr = 0;
  int i;
  int iVerbose = 1;               /* -verbose option */

  sqlite3 *db = 0;
  sqlite3expert *p = 0;

  if( argc<2 ) usage(argv);
  zDb = argv[argc-1];
  if( zDb[0]=='-' ) usage(argv);
  rc = sqlite3_open(zDb, &db);
  if( rc!=SQLITE_OK ){
    fprintf(stderr, "Cannot open db file: %s - %s\n", zDb, sqlite3_errmsg(db));
    exit(-2);
  }

  p = sqlite3_expert_new(db, &zErr);
  if( p==0 ){
    fprintf(stderr, "Cannot run analysis: %s\n", zErr);
    rc = 1;
  }else{
    for(i=1; i<(argc-1); i++){
      char *zArg = argv[i];
      if( zArg[0]=='-' && zArg[1]=='-' && zArg[2]!=0 ) zArg++;
      int nArg = (int)strlen(zArg);
      if( nArg>=2 && 0==sqlite3_strnicmp(zArg, "-file", nArg) ){
        if( ++i==(argc-1) ) option_requires_argument("-file");
        rc = readSqlFromFile(p, argv[i], &zErr);
      }

      else if( nArg>=3 && 0==sqlite3_strnicmp(zArg, "-sql", nArg) ){
        if( ++i==(argc-1) ) option_requires_argument("-sql");
        rc = sqlite3_expert_sql(p, argv[i], &zErr);
      }

      else if( nArg>=3 && 0==sqlite3_strnicmp(zArg, "-sample", nArg) ){
        int iSample;
        if( ++i==(argc-1) ) option_requires_argument("-sample");
        iSample = option_integer_arg(argv[i]);
        sqlite3_expert_config(p, EXPERT_CONFIG_SAMPLE, iSample);
      }

      else if( nArg>=2 && 0==sqlite3_strnicmp(zArg, "-verbose", nArg) ){
        if( ++i==(argc-1) ) option_requires_argument("-verbose");
        iVerbose = option_integer_arg(argv[i]);
      }

      else{
        usage(argv);
      }
    }
  }

  if( rc==SQLITE_OK ){
    rc = sqlite3_expert_analyze(p, &zErr);
  }

  if( rc==SQLITE_OK ){
    int nQuery = sqlite3_expert_count(p);
    if( iVerbose>0 ){
      const char *zCand = sqlite3_expert_report(p,0,EXPERT_REPORT_CANDIDATES);
      fprintf(stdout, "-- Candidates -------------------------------\n");
      fprintf(stdout, "%s\n", zCand);
    }
    for(i=0; i<nQuery; i++){
      const char *zSql = sqlite3_expert_report(p, i, EXPERT_REPORT_SQL);
      const char *zIdx = sqlite3_expert_report(p, i, EXPERT_REPORT_INDEXES);
      const char *zEQP = sqlite3_expert_report(p, i, EXPERT_REPORT_PLAN);
      if( zIdx==0 ) zIdx = "(no new indexes)\n";
      if( iVerbose>0 ){
        fprintf(stdout, "-- Query %d ----------------------------------\n",i+1);
        fprintf(stdout, "%s\n\n", zSql);
      }
      fprintf(stdout, "%s\n%s\n", zIdx, zEQP);
    }
  }else{
    fprintf(stderr, "Error: %s\n", zErr ? zErr : "?");
  }

  sqlite3_expert_destroy(p);
  sqlite3_free(zErr);
  return rc;
}

# 2009 Nov 11
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# The focus of this file is testing the CLI shell tool. Specifically,
# the ".recommend" command.
#
#

# Test plan:
#
#
if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
}
source $testdir/tester.tcl
set testprefix expert1

if {[info commands sqlite3_expert_new]==""} {
  finish_test
  return
}

set CLI [test_binary_name sqlite3]
set CMD [test_binary_name sqlite3_expert]

proc squish {txt} {
  regsub -all {[[:space:]]+} $txt { }
}

proc do_setup_rec_test {tn setup sql res} {
  reset_db
  db eval $setup
  uplevel [list do_rec_test $tn $sql $res]
}

foreach {tn setup} {
  1 {
    if {![file executable $CMD]} { continue }

    proc do_rec_test {tn sql res} {
      set res [squish [string trim $res]]
      set tst [subst -nocommands { 
        squish [string trim [exec $::CMD -verbose 0 -sql {$sql;} test.db]]
      }]
      uplevel [list do_test $tn $tst $res]
    }
  }
  2 {
    if {[info commands sqlite3_expert_new]==""} { continue }

    proc do_rec_test {tn sql res} {
      set expert [sqlite3_expert_new db]
      $expert sql $sql
      $expert analyze

      set result [list]
      for {set i 0} {$i < [$expert count]} {incr i} {
        set idx [string trim [$expert report $i indexes]]
        if {$idx==""} {set idx "(no new indexes)"}
        lappend result $idx
        lappend result [string trim [$expert report $i plan]]
      }

      $expert destroy

      set tst [subst -nocommands {set {} [squish [join {$result}]]}]
      uplevel [list do_test $tn $tst [string trim [squish $res]]]
    }
  }
  3 {
    if {![file executable $CLI]} { continue }

    proc do_rec_test {tn sql res} {
      set res [squish [string trim $res]]
      set tst [subst -nocommands { 
        squish [string trim [exec $::CLI test.db ".expert" {$sql;}]]
      }]
      uplevel [list do_test $tn $tst $res]
    }
  }
} {

  eval $setup


do_setup_rec_test $tn.1 { CREATE TABLE t1(a, b, c) } {
  SELECT * FROM t1
} {
  (no new indexes)
  0|0|0|SCAN TABLE t1
}

do_setup_rec_test $tn.2 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT * FROM t1 WHERE b>?;
} {
  CREATE INDEX t1_idx_00000062 ON t1(b);
  0|0|0|SEARCH TABLE t1 USING INDEX t1_idx_00000062 (b>?)
}

do_setup_rec_test $tn.3 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT * FROM t1 WHERE b COLLATE nocase BETWEEN ? AND ?
} {
  CREATE INDEX t1_idx_3e094c27 ON t1(b COLLATE NOCASE);
  0|0|0|SEARCH TABLE t1 USING INDEX t1_idx_3e094c27 (b>? AND b<?)
}

do_setup_rec_test $tn.4 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT a FROM t1 ORDER BY b;
} {
  CREATE INDEX t1_idx_00000062 ON t1(b);
  0|0|0|SCAN TABLE t1 USING INDEX t1_idx_00000062
}

do_setup_rec_test $tn.5 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT a FROM t1 WHERE a=? ORDER BY b;
} {
  CREATE INDEX t1_idx_000123a7 ON t1(a, b);
  0|0|0|SEARCH TABLE t1 USING COVERING INDEX t1_idx_000123a7 (a=?)
}

do_setup_rec_test $tn.6 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT min(a) FROM t1
} {
  CREATE INDEX t1_idx_00000061 ON t1(a);
  0|0|0|SEARCH TABLE t1 USING COVERING INDEX t1_idx_00000061
}

do_setup_rec_test $tn.7 {
  CREATE TABLE t1(a, b, c);
} {
  SELECT * FROM t1 ORDER BY a, b, c;
} {
  CREATE INDEX t1_idx_033e95fe ON t1(a, b, c);
  0|0|0|SCAN TABLE t1 USING COVERING INDEX t1_idx_033e95fe
}

#do_setup_rec_test $tn.1.8 {
#  CREATE TABLE t1(a, b, c);
#} {
#  SELECT * FROM t1 ORDER BY a ASC, b COLLATE nocase DESC, c ASC;
#} {
#  CREATE INDEX t1_idx_5be6e222 ON t1(a, b COLLATE NOCASE DESC, c);
#  0|0|0|SCAN TABLE t1 USING COVERING INDEX t1_idx_5be6e222
#}

do_setup_rec_test $tn.8.1 {
  CREATE TABLE t1(a COLLATE NOCase, b, c);
} {
  SELECT * FROM t1 WHERE a=?
} {
  CREATE INDEX t1_idx_00000061 ON t1(a);
  0|0|0|SEARCH TABLE t1 USING INDEX t1_idx_00000061 (a=?)
}
do_setup_rec_test $tn.8.2 {
  CREATE TABLE t1(a, b COLLATE nocase, c);
} {
  SELECT * FROM t1 ORDER BY a ASC, b DESC, c ASC;
} {
  CREATE INDEX t1_idx_5cb97285 ON t1(a, b DESC, c);
  0|0|0|SCAN TABLE t1 USING COVERING INDEX t1_idx_5cb97285
}


# Tables with names that require quotes.
#
do_setup_rec_test $tn.9.1 {
  CREATE TABLE "t t"(a, b, c);
} {
  SELECT * FROM "t t" WHERE a=?
} {
  CREATE INDEX 't t_idx_00000061' ON 't t'(a);
  0|0|0|SEARCH TABLE t t USING INDEX t t_idx_00000061 (a=?) 
}

do_setup_rec_test $tn.9.2 {
  CREATE TABLE "t t"(a, b, c);
} {
  SELECT * FROM "t t" WHERE b BETWEEN ? AND ?
} {
  CREATE INDEX 't t_idx_00000062' ON 't t'(b);
  0|0|0|SEARCH TABLE t t USING INDEX t t_idx_00000062 (b>? AND b<?)
}

# Columns with names that require quotes.
#
do_setup_rec_test $tn.10.1 {
  CREATE TABLE t3(a, "b b", c);
} {
  SELECT * FROM t3 WHERE "b b" = ?
} {
  CREATE INDEX t3_idx_00050c52 ON t3('b b');
  0|0|0|SEARCH TABLE t3 USING INDEX t3_idx_00050c52 (b b=?)
}

do_setup_rec_test $tn.10.2 {
  CREATE TABLE t3(a, "b b", c);
} {
  SELECT * FROM t3 ORDER BY "b b"
} {
  CREATE INDEX t3_idx_00050c52 ON t3('b b');
  0|0|0|SCAN TABLE t3 USING INDEX t3_idx_00050c52
}

# Transitive constraints
#
do_setup_rec_test $tn.11.1 {
  CREATE TABLE t5(a, b);
  CREATE TABLE t6(c, d);
} {
  SELECT * FROM t5, t6 WHERE a=? AND b=c AND c=?
} {
  CREATE INDEX t5_idx_000123a7 ON t5(a, b);
  CREATE INDEX t6_idx_00000063 ON t6(c);
  0|0|1|SEARCH TABLE t6 USING INDEX t6_idx_00000063 (c=?) 
  0|1|0|SEARCH TABLE t5 USING COVERING INDEX t5_idx_000123a7 (a=? AND b=?)
}

# OR terms.
#
do_setup_rec_test $tn.12.1 {
  CREATE TABLE t7(a, b);
} {
  SELECT * FROM t7 WHERE a=? OR b=?
} {
  CREATE INDEX t7_idx_00000062 ON t7(b);
  CREATE INDEX t7_idx_00000061 ON t7(a);
  0|0|0|SEARCH TABLE t7 USING INDEX t7_idx_00000061 (a=?) 
  0|0|0|SEARCH TABLE t7 USING INDEX t7_idx_00000062 (b=?)
}

# rowid terms.
#
do_setup_rec_test $tn.13.1 {
  CREATE TABLE t8(a, b);
} {
  SELECT * FROM t8 WHERE rowid=?
} {
  (no new indexes)
  0|0|0|SEARCH TABLE t8 USING INTEGER PRIMARY KEY (rowid=?)
}
do_setup_rec_test $tn.13.2 {
  CREATE TABLE t8(a, b);
} {
  SELECT * FROM t8 ORDER BY rowid
} {
  (no new indexes)
  0|0|0|SCAN TABLE t8
}
do_setup_rec_test $tn.13.3 {
  CREATE TABLE t8(a, b);
} {
  SELECT * FROM t8 WHERE a=? ORDER BY rowid
} {
  CREATE INDEX t8_idx_00000061 ON t8(a); 
  0|0|0|SEARCH TABLE t8 USING INDEX t8_idx_00000061 (a=?)
}

# Triggers
#
do_setup_rec_test $tn.14 {
  CREATE TABLE t9(a, b, c);
  CREATE TABLE t10(a, b, c);
  CREATE TRIGGER t9t AFTER INSERT ON t9 BEGIN
    UPDATE t10 SET a=new.a WHERE b = new.b;
  END;
} {
  INSERT INTO t9 VALUES(?, ?, ?);
} {
  CREATE INDEX t10_idx_00000062 ON t10(b); 
  0|0|0|SEARCH TABLE t10 USING INDEX t10_idx_00000062 (b=?)
}

do_setup_rec_test $tn.15 {
  CREATE TABLE t1(a, b);
  CREATE TABLE t2(c, d);

  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100)
  INSERT INTO t1 SELECT (i-1)/50, (i-1)/20 FROM s;

  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100)
  INSERT INTO t2 SELECT (i-1)/20, (i-1)/5 FROM s;
} {
  SELECT * FROM t2, t1 WHERE b=? AND d=? AND t2.rowid=t1.rowid
} {
  CREATE INDEX t2_idx_00000064 ON t2(d);
  0|0|0|SEARCH TABLE t2 USING INDEX t2_idx_00000064 (d=?) 
  0|1|1|SEARCH TABLE t1 USING INTEGER PRIMARY KEY (rowid=?)
}

do_setup_rec_test $tn.16 {
  CREATE TABLE t1(a, b);
} {
  SELECT * FROM t1 WHERE b IS NOT NULL;
} {
  (no new indexes)
  0|0|0|SCAN TABLE t1
}

}

proc do_candidates_test {tn sql res} {
  set res [squish [string trim $res]]

  set expert [sqlite3_expert_new db]
  $expert sql $sql
  $expert analyze

  set candidates [squish [string trim [$expert report 0 candidates]]]
  $expert destroy

  uplevel [list do_test $tn [list set {} $candidates] $res]
}


reset_db
do_execsql_test 3.0 {
  CREATE TABLE t1(a, b);
  CREATE TABLE t2(c, d);

  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100)
  INSERT INTO t1 SELECT (i-1)/50, (i-1)/20 FROM s;

  WITH s(i) AS ( VALUES(1) UNION ALL SELECT i+1 FROM s WHERE i<100)
  INSERT INTO t2 SELECT (i-1)/20, (i-1)/5 FROM s;
}
do_candidates_test 3.1 {
  SELECT * FROM t1,t2 WHERE (b=? OR a=?) AND (c=? OR d=?)
} {
  CREATE INDEX t1_idx_00000062 ON t1(b); -- stat1: 100 20 
  CREATE INDEX t1_idx_00000061 ON t1(a); -- stat1: 100 50 
  CREATE INDEX t2_idx_00000063 ON t2(c); -- stat1: 100 20 
  CREATE INDEX t2_idx_00000064 ON t2(d); -- stat1: 100 5
}

do_candidates_test 3.2 {
  SELECT * FROM t1,t2 WHERE a=? AND b=? AND c=? AND d=?
} {
  CREATE INDEX t1_idx_000123a7 ON t1(a, b); -- stat1: 100 50 17
  CREATE INDEX t2_idx_0001295b ON t2(c, d); -- stat1: 100 20 5
}

do_execsql_test 3.2 {
  CREATE INDEX t1_idx_00000061 ON t1(a); -- stat1: 100 50 
  CREATE INDEX t1_idx_00000062 ON t1(b); -- stat1: 100 20 
  CREATE INDEX t1_idx_000123a7 ON t1(a, b); -- stat1: 100 50 16

  CREATE INDEX t2_idx_00000063 ON t2(c); -- stat1: 100 20 
  CREATE INDEX t2_idx_00000064 ON t2(d); -- stat1: 100 5
  CREATE INDEX t2_idx_0001295b ON t2(c, d); -- stat1: 100 20 5

  ANALYZE;
  SELECT * FROM sqlite_stat1 ORDER BY 1, 2;
} {
  t1 t1_idx_00000061 {100 50} 
  t1 t1_idx_00000062 {100 20}
  t1 t1_idx_000123a7 {100 50 17}
  t2 t2_idx_00000063 {100 20} 
  t2 t2_idx_00000064 {100 5} 
  t2 t2_idx_0001295b {100 20 5}
}


finish_test

/*
** 2017 April 09
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
*/
#include "sqlite3expert.h"
#include <assert.h>
#include <string.h>
#include <stdio.h>

#ifndef SQLITE_OMIT_VIRTUALTABLE 

typedef sqlite3_int64 i64;
typedef sqlite3_uint64 u64;

typedef struct IdxColumn IdxColumn;
typedef struct IdxConstraint IdxConstraint;
typedef struct IdxScan IdxScan;
typedef struct IdxStatement IdxStatement;
typedef struct IdxTable IdxTable;
typedef struct IdxWrite IdxWrite;

#define STRLEN  (int)strlen

/*
** A temp table name that we assume no user database will actually use.
** If this assumption proves incorrect triggers on the table with the
** conflicting name will be ignored.
*/
#define UNIQUE_TABLE_NAME "t592690916721053953805701627921227776"

/*
** A single constraint. Equivalent to either "col = ?" or "col < ?" (or
** any other type of single-ended range constraint on a column).
**
** pLink:
**   Used to temporarily link IdxConstraint objects into lists while
**   creating candidate indexes.
*/
struct IdxConstraint {
  char *zColl;                    /* Collation sequence */
  int bRange;                     /* True for range, false for eq */
  int iCol;                       /* Constrained table column */
  int bFlag;                      /* Used by idxFindCompatible() */
  int bDesc;                      /* True if ORDER BY <expr> DESC */
  IdxConstraint *pNext;           /* Next constraint in pEq or pRange list */
  IdxConstraint *pLink;           /* See above */
};

/*
** A single scan of a single table.
*/
struct IdxScan {
  IdxTable *pTab;                 /* Associated table object */
  int iDb;                        /* Database containing table zTable */
  i64 covering;                   /* Mask of columns required for cov. index */
  IdxConstraint *pOrder;          /* ORDER BY columns */
  IdxConstraint *pEq;             /* List of == constraints */
  IdxConstraint *pRange;          /* List of < constraints */
  IdxScan *pNextScan;             /* Next IdxScan object for same analysis */
};

/*
** Information regarding a single database table. Extracted from 
** "PRAGMA table_info" by function idxGetTableInfo().
*/
struct IdxColumn {
  char *zName;
  char *zColl;
  int iPk;
};
struct IdxTable {
  int nCol;
  char *zName;                    /* Table name */
  IdxColumn *aCol;
  IdxTable *pNext;                /* Next table in linked list of all tables */
};

/*
** An object of the following type is created for each unique table/write-op
** seen. The objects are stored in a singly-linked list beginning at
** sqlite3expert.pWrite.
*/
struct IdxWrite {
  IdxTable *pTab;
  int eOp;                        /* SQLITE_UPDATE, DELETE or INSERT */
  IdxWrite *pNext;
};

/*
** Each statement being analyzed is represented by an instance of this
** structure.
*/
struct IdxStatement {
  int iId;                        /* Statement number */
  char *zSql;                     /* SQL statement */
  char *zIdx;                     /* Indexes */
  char *zEQP;                     /* Plan */
  IdxStatement *pNext;
};


/*
** A hash table for storing strings. With space for a payload string
** with each entry. Methods are:
**
**   idxHashInit()
**   idxHashClear()
**   idxHashAdd()
**   idxHashSearch()
*/
#define IDX_HASH_SIZE 1023
typedef struct IdxHashEntry IdxHashEntry;
typedef struct IdxHash IdxHash;
struct IdxHashEntry {
  char *zKey;                     /* nul-terminated key */
  char *zVal;                     /* nul-terminated value string */
  char *zVal2;                    /* nul-terminated value string 2 */
  IdxHashEntry *pHashNext;        /* Next entry in same hash bucket */
  IdxHashEntry *pNext;            /* Next entry in hash */
};
struct IdxHash {
  IdxHashEntry *pFirst;
  IdxHashEntry *aHash[IDX_HASH_SIZE];
};

/*
** sqlite3expert object.
*/
struct sqlite3expert {
  int iSample;                    /* Percentage of tables to sample for stat1 */
  sqlite3 *db;                    /* User database */
  sqlite3 *dbm;                   /* In-memory db for this analysis */
  sqlite3 *dbv;                   /* Vtab schema for this analysis */
  IdxTable *pTable;               /* List of all IdxTable objects */
  IdxScan *pScan;                 /* List of scan objects */
  IdxWrite *pWrite;               /* List of write objects */
  IdxStatement *pStatement;       /* List of IdxStatement objects */
  int bRun;                       /* True once analysis has run */
  char **pzErrmsg;
  int rc;                         /* Error code from whereinfo hook */
  IdxHash hIdx;                   /* Hash containing all candidate indexes */
  char *zCandidates;              /* For EXPERT_REPORT_CANDIDATES */
};


/*
** Allocate and return nByte bytes of zeroed memory using sqlite3_malloc(). 
** If the allocation fails, set *pRc to SQLITE_NOMEM and return NULL.
*/
static void *idxMalloc(int *pRc, int nByte){
  void *pRet;
  assert( *pRc==SQLITE_OK );
  assert( nByte>0 );
  pRet = sqlite3_malloc(nByte);
  if( pRet ){
    memset(pRet, 0, nByte);
  }else{
    *pRc = SQLITE_NOMEM;
  }
  return pRet;
}

/*
** Initialize an IdxHash hash table.
*/
static void idxHashInit(IdxHash *pHash){
  memset(pHash, 0, sizeof(IdxHash));
}

/*
** Reset an IdxHash hash table.
*/
static void idxHashClear(IdxHash *pHash){
  int i;
  for(i=0; i<IDX_HASH_SIZE; i++){
    IdxHashEntry *pEntry;
    IdxHashEntry *pNext;
    for(pEntry=pHash->aHash[i]; pEntry; pEntry=pNext){
      pNext = pEntry->pHashNext;
      sqlite3_free(pEntry->zVal2);
      sqlite3_free(pEntry);
    }
  }
  memset(pHash, 0, sizeof(IdxHash));
}

/*
** Return the index of the hash bucket that the string specified by the
** arguments to this function belongs.
*/
static int idxHashString(const char *z, int n){
  unsigned int ret = 0;
  int i;
  for(i=0; i<n; i++){
    ret += (ret<<3) + (unsigned char)(z[i]);
  }
  return (int)(ret % IDX_HASH_SIZE);
}

/*
** If zKey is already present in the hash table, return non-zero and do
** nothing. Otherwise, add an entry with key zKey and payload string zVal to
** the hash table passed as the second argument. 
*/
static int idxHashAdd(
  int *pRc, 
  IdxHash *pHash, 
  const char *zKey,
  const char *zVal
){
  int nKey = STRLEN(zKey);
  int iHash = idxHashString(zKey, nKey);
  int nVal = (zVal ? STRLEN(zVal) : 0);
  IdxHashEntry *pEntry;
  assert( iHash>=0 );
  for(pEntry=pHash->aHash[iHash]; pEntry; pEntry=pEntry->pHashNext){
    if( STRLEN(pEntry->zKey)==nKey && 0==memcmp(pEntry->zKey, zKey, nKey) ){
      return 1;
    }
  }
  pEntry = idxMalloc(pRc, sizeof(IdxHashEntry) + nKey+1 + nVal+1);
  if( pEntry ){
    pEntry->zKey = (char*)&pEntry[1];
    memcpy(pEntry->zKey, zKey, nKey);
    if( zVal ){
      pEntry->zVal = &pEntry->zKey[nKey+1];
      memcpy(pEntry->zVal, zVal, nVal);
    }
    pEntry->pHashNext = pHash->aHash[iHash];
    pHash->aHash[iHash] = pEntry;

    pEntry->pNext = pHash->pFirst;
    pHash->pFirst = pEntry;
  }
  return 0;
}

/*
** If zKey/nKey is present in the hash table, return a pointer to the 
** hash-entry object.
*/
static IdxHashEntry *idxHashFind(IdxHash *pHash, const char *zKey, int nKey){
  int iHash;
  IdxHashEntry *pEntry;
  if( nKey<0 ) nKey = STRLEN(zKey);
  iHash = idxHashString(zKey, nKey);
  assert( iHash>=0 );
  for(pEntry=pHash->aHash[iHash]; pEntry; pEntry=pEntry->pHashNext){
    if( STRLEN(pEntry->zKey)==nKey && 0==memcmp(pEntry->zKey, zKey, nKey) ){
      return pEntry;
    }
  }
  return 0;
}

/*
** If the hash table contains an entry with a key equal to the string
** passed as the final two arguments to this function, return a pointer
** to the payload string. Otherwise, if zKey/nKey is not present in the
** hash table, return NULL.
*/
static const char *idxHashSearch(IdxHash *pHash, const char *zKey, int nKey){
  IdxHashEntry *pEntry = idxHashFind(pHash, zKey, nKey);
  if( pEntry ) return pEntry->zVal;
  return 0;
}

/*
** Allocate and return a new IdxConstraint object. Set the IdxConstraint.zColl
** variable to point to a copy of nul-terminated string zColl.
*/
static IdxConstraint *idxNewConstraint(int *pRc, const char *zColl){
  IdxConstraint *pNew;
  int nColl = STRLEN(zColl);

  assert( *pRc==SQLITE_OK );
  pNew = (IdxConstraint*)idxMalloc(pRc, sizeof(IdxConstraint) * nColl + 1);
  if( pNew ){
    pNew->zColl = (char*)&pNew[1];
    memcpy(pNew->zColl, zColl, nColl+1);
  }
  return pNew;
}

/*
** An error associated with database handle db has just occurred. Pass
** the error message to callback function xOut.
*/
static void idxDatabaseError(
  sqlite3 *db,                    /* Database handle */
  char **pzErrmsg                 /* Write error here */
){
  *pzErrmsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
}

/*
** Prepare an SQL statement.
*/
static int idxPrepareStmt(
  sqlite3 *db,                    /* Database handle to compile against */
  sqlite3_stmt **ppStmt,          /* OUT: Compiled SQL statement */
  char **pzErrmsg,                /* OUT: sqlite3_malloc()ed error message */
  const char *zSql                /* SQL statement to compile */
){
  int rc = sqlite3_prepare_v2(db, zSql, -1, ppStmt, 0);
  if( rc!=SQLITE_OK ){
    *ppStmt = 0;
    idxDatabaseError(db, pzErrmsg);
  }
  return rc;
}

/*
** Prepare an SQL statement using the results of a printf() formatting.
*/
static int idxPrintfPrepareStmt(
  sqlite3 *db,                    /* Database handle to compile against */
  sqlite3_stmt **ppStmt,          /* OUT: Compiled SQL statement */
  char **pzErrmsg,                /* OUT: sqlite3_malloc()ed error message */
  const char *zFmt,               /* printf() format of SQL statement */
  ...                             /* Trailing printf() arguments */
){
  va_list ap;
  int rc;
  char *zSql;
  va_start(ap, zFmt);
  zSql = sqlite3_vmprintf(zFmt, ap);
  if( zSql==0 ){
    rc = SQLITE_NOMEM;
  }else{
    rc = idxPrepareStmt(db, ppStmt, pzErrmsg, zSql);
    sqlite3_free(zSql);
  }
  va_end(ap);
  return rc;
}


/*************************************************************************
** Beginning of virtual table implementation.
*/
typedef struct ExpertVtab ExpertVtab;
struct ExpertVtab {
  sqlite3_vtab base;
  IdxTable *pTab;
  sqlite3expert *pExpert;
};

typedef struct ExpertCsr ExpertCsr;
struct ExpertCsr {
  sqlite3_vtab_cursor base;
  sqlite3_stmt *pData;
};

static char *expertDequote(const char *zIn){
  int n = STRLEN(zIn);
  char *zRet = sqlite3_malloc(n);

  assert( zIn[0]=='\'' );
  assert( zIn[n-1]=='\'' );

  if( zRet ){
    int iOut = 0;
    int iIn = 0;
    for(iIn=1; iIn<(n-1); iIn++){
      if( zIn[iIn]=='\'' ){
        assert( zIn[iIn+1]=='\'' );
        iIn++;
      }
      zRet[iOut++] = zIn[iIn];
    }
    zRet[iOut] = '\0';
  }

  return zRet;
}

/* 
** This function is the implementation of both the xConnect and xCreate
** methods of the r-tree virtual table.
**
**   argv[0]   -> module name
**   argv[1]   -> database name
**   argv[2]   -> table name
**   argv[...] -> column names...
*/
static int expertConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  sqlite3expert *pExpert = (sqlite3expert*)pAux;
  ExpertVtab *p = 0;
  int rc;

  if( argc!=4 ){
    *pzErr = sqlite3_mprintf("internal error!");
    rc = SQLITE_ERROR;
  }else{
    char *zCreateTable = expertDequote(argv[3]);
    if( zCreateTable ){
      rc = sqlite3_declare_vtab(db, zCreateTable);
      if( rc==SQLITE_OK ){
        p = idxMalloc(&rc, sizeof(ExpertVtab));
      }
      if( rc==SQLITE_OK ){
        p->pExpert = pExpert;
        p->pTab = pExpert->pTable;
        assert( sqlite3_stricmp(p->pTab->zName, argv[2])==0 );
      }
      sqlite3_free(zCreateTable);
    }else{
      rc = SQLITE_NOMEM;
    }
  }

  *ppVtab = (sqlite3_vtab*)p;
  return rc;
}

static int expertDisconnect(sqlite3_vtab *pVtab){
  ExpertVtab *p = (ExpertVtab*)pVtab;
  sqlite3_free(p);
  return SQLITE_OK;
}

static int expertBestIndex(sqlite3_vtab *pVtab, sqlite3_index_info *pIdxInfo){
  ExpertVtab *p = (ExpertVtab*)pVtab;
  int rc = SQLITE_OK;
  int n = 0;
  IdxScan *pScan;
  const int opmask = 
    SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_GT |
    SQLITE_INDEX_CONSTRAINT_LT | SQLITE_INDEX_CONSTRAINT_GE |
    SQLITE_INDEX_CONSTRAINT_LE;

  pScan = idxMalloc(&rc, sizeof(IdxScan));
  if( pScan ){
    int i;

    /* Link the new scan object into the list */
    pScan->pTab = p->pTab;
    pScan->pNextScan = p->pExpert->pScan;
    p->pExpert->pScan = pScan;

    /* Add the constraints to the IdxScan object */
    for(i=0; i<pIdxInfo->nConstraint; i++){
      struct sqlite3_index_constraint *pCons = &pIdxInfo->aConstraint[i];
      if( pCons->usable 
       && pCons->iColumn>=0 
       && p->pTab->aCol[pCons->iColumn].iPk==0
       && (pCons->op & opmask) 
      ){
        IdxConstraint *pNew;
        const char *zColl = sqlite3_vtab_collation(pIdxInfo, i);
        pNew = idxNewConstraint(&rc, zColl);
        if( pNew ){
          pNew->iCol = pCons->iColumn;
          if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ ){
            pNew->pNext = pScan->pEq;
            pScan->pEq = pNew;
          }else{
            pNew->bRange = 1;
            pNew->pNext = pScan->pRange;
            pScan->pRange = pNew;
          }
        }
        n++;
        pIdxInfo->aConstraintUsage[i].argvIndex = n;
      }
    }

    /* Add the ORDER BY to the IdxScan object */
    for(i=pIdxInfo->nOrderBy-1; i>=0; i--){
      int iCol = pIdxInfo->aOrderBy[i].iColumn;
      if( iCol>=0 ){
        IdxConstraint *pNew = idxNewConstraint(&rc, p->pTab->aCol[iCol].zColl);
        if( pNew ){
          pNew->iCol = iCol;
          pNew->bDesc = pIdxInfo->aOrderBy[i].desc;
          pNew->pNext = pScan->pOrder;
          pNew->pLink = pScan->pOrder;
          pScan->pOrder = pNew;
          n++;
        }
      }
    }
  }

  pIdxInfo->estimatedCost = 1000000.0 / (n+1);
  return rc;
}

static int expertUpdate(
  sqlite3_vtab *pVtab, 
  int nData, 
  sqlite3_value **azData, 
  sqlite_int64 *pRowid
){
  return SQLITE_OK;
}

/* 
** Virtual table module xOpen method.
*/
static int expertOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
  int rc = SQLITE_OK;
  ExpertCsr *pCsr;
  pCsr = idxMalloc(&rc, sizeof(ExpertCsr));
  *ppCursor = (sqlite3_vtab_cursor*)pCsr;
  return rc;
}

/* 
** Virtual table module xClose method.
*/
static int expertClose(sqlite3_vtab_cursor *cur){
  ExpertCsr *pCsr = (ExpertCsr*)cur;
  sqlite3_finalize(pCsr->pData);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Virtual table module xEof method.
**
** Return non-zero if the cursor does not currently point to a valid 
** record (i.e if the scan has finished), or zero otherwise.
*/
static int expertEof(sqlite3_vtab_cursor *cur){
  ExpertCsr *pCsr = (ExpertCsr*)cur;
  return pCsr->pData==0;
}

/* 
** Virtual table module xNext method.
*/
static int expertNext(sqlite3_vtab_cursor *cur){
  ExpertCsr *pCsr = (ExpertCsr*)cur;
  int rc = SQLITE_OK;

  assert( pCsr->pData );
  rc = sqlite3_step(pCsr->pData);
  if( rc!=SQLITE_ROW ){
    rc = sqlite3_finalize(pCsr->pData);
    pCsr->pData = 0;
  }else{
    rc = SQLITE_OK;
  }

  return rc;
}

/* 
** Virtual table module xRowid method.
*/
static int expertRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  *pRowid = 0;
  return SQLITE_OK;
}

/* 
** Virtual table module xColumn method.
*/
static int expertColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  ExpertCsr *pCsr = (ExpertCsr*)cur;
  sqlite3_value *pVal;
  pVal = sqlite3_column_value(pCsr->pData, i);
  if( pVal ){
    sqlite3_result_value(ctx, pVal);
  }
  return SQLITE_OK;
}

/* 
** Virtual table module xFilter method.
*/
static int expertFilter(
  sqlite3_vtab_cursor *cur, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  ExpertCsr *pCsr = (ExpertCsr*)cur;
  ExpertVtab *pVtab = (ExpertVtab*)(cur->pVtab);
  sqlite3expert *pExpert = pVtab->pExpert;
  int rc;

  rc = sqlite3_finalize(pCsr->pData);
  pCsr->pData = 0;
  if( rc==SQLITE_OK ){
    rc = idxPrintfPrepareStmt(pExpert->db, &pCsr->pData, &pVtab->base.zErrMsg,
        "SELECT * FROM main.%Q WHERE sample()", pVtab->pTab->zName
    );
  }

  if( rc==SQLITE_OK ){
    rc = expertNext(cur);
  }
  return rc;
}

static int idxRegisterVtab(sqlite3expert *p){
  static sqlite3_module expertModule = {
    2,                            /* iVersion */
    expertConnect,                /* xCreate - create a table */
    expertConnect,                /* xConnect - connect to an existing table */
    expertBestIndex,              /* xBestIndex - Determine search strategy */
    expertDisconnect,             /* xDisconnect - Disconnect from a table */
    expertDisconnect,             /* xDestroy - Drop a table */
    expertOpen,                   /* xOpen - open a cursor */
    expertClose,                  /* xClose - close a cursor */
    expertFilter,                 /* xFilter - configure scan constraints */
    expertNext,                   /* xNext - advance a cursor */
    expertEof,                    /* xEof */
    expertColumn,                 /* xColumn - read data */
    expertRowid,                  /* xRowid - read data */
    expertUpdate,                 /* xUpdate - write data */
    0,                            /* xBegin - begin transaction */
    0,                            /* xSync - sync transaction */
    0,                            /* xCommit - commit transaction */
    0,                            /* xRollback - rollback transaction */
    0,                            /* xFindFunction - function overloading */
    0,                            /* xRename - rename the table */
    0,                            /* xSavepoint */
    0,                            /* xRelease */
    0,                            /* xRollbackTo */
  };

  return sqlite3_create_module(p->dbv, "expert", &expertModule, (void*)p);
}
/*
** End of virtual table implementation.
*************************************************************************/
/*
** Finalize SQL statement pStmt. If (*pRc) is SQLITE_OK when this function
** is called, set it to the return value of sqlite3_finalize() before
** returning. Otherwise, discard the sqlite3_finalize() return value.
*/
static void idxFinalize(int *pRc, sqlite3_stmt *pStmt){
  int rc = sqlite3_finalize(pStmt);
  if( *pRc==SQLITE_OK ) *pRc = rc;
}

/*
** Attempt to allocate an IdxTable structure corresponding to table zTab
** in the main database of connection db. If successful, set (*ppOut) to
** point to the new object and return SQLITE_OK. Otherwise, return an
** SQLite error code and set (*ppOut) to NULL. In this case *pzErrmsg may be
** set to point to an error string.
**
** It is the responsibility of the caller to eventually free either the
** IdxTable object or error message using sqlite3_free().
*/
static int idxGetTableInfo(
  sqlite3 *db,                    /* Database connection to read details from */
  const char *zTab,               /* Table name */
  IdxTable **ppOut,               /* OUT: New object (if successful) */
  char **pzErrmsg                 /* OUT: Error message (if not) */
){
  sqlite3_stmt *p1 = 0;
  int nCol = 0;
  int nTab = STRLEN(zTab);
  int nByte = sizeof(IdxTable) + nTab + 1;
  IdxTable *pNew = 0;
  int rc, rc2;
  char *pCsr = 0;

  rc = idxPrintfPrepareStmt(db, &p1, pzErrmsg, "PRAGMA table_info=%Q", zTab);
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(p1) ){
    const char *zCol = (const char*)sqlite3_column_text(p1, 1);
    nByte += 1 + STRLEN(zCol);
    rc = sqlite3_table_column_metadata(
        db, "main", zTab, zCol, 0, &zCol, 0, 0, 0
    );
    nByte += 1 + STRLEN(zCol);
    nCol++;
  }
  rc2 = sqlite3_reset(p1);
  if( rc==SQLITE_OK ) rc = rc2;

  nByte += sizeof(IdxColumn) * nCol;
  if( rc==SQLITE_OK ){
    pNew = idxMalloc(&rc, nByte);
  }
  if( rc==SQLITE_OK ){
    pNew->aCol = (IdxColumn*)&pNew[1];
    pNew->nCol = nCol;
    pCsr = (char*)&pNew->aCol[nCol];
  }

  nCol = 0;
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(p1) ){
    const char *zCol = (const char*)sqlite3_column_text(p1, 1);
    int nCopy = STRLEN(zCol) + 1;
    pNew->aCol[nCol].zName = pCsr;
    pNew->aCol[nCol].iPk = sqlite3_column_int(p1, 5);
    memcpy(pCsr, zCol, nCopy);
    pCsr += nCopy;

    rc = sqlite3_table_column_metadata(
        db, "main", zTab, zCol, 0, &zCol, 0, 0, 0
    );
    if( rc==SQLITE_OK ){
      nCopy = STRLEN(zCol) + 1;
      pNew->aCol[nCol].zColl = pCsr;
      memcpy(pCsr, zCol, nCopy);
      pCsr += nCopy;
    }

    nCol++;
  }
  idxFinalize(&rc, p1);

  if( rc!=SQLITE_OK ){
    sqlite3_free(pNew);
    pNew = 0;
  }else{
    pNew->zName = pCsr;
    memcpy(pNew->zName, zTab, nTab+1);
  }

  *ppOut = pNew;
  return rc;
}

/*
** This function is a no-op if *pRc is set to anything other than 
** SQLITE_OK when it is called.
**
** If *pRc is initially set to SQLITE_OK, then the text specified by
** the printf() style arguments is appended to zIn and the result returned
** in a buffer allocated by sqlite3_malloc(). sqlite3_free() is called on
** zIn before returning.
*/
static char *idxAppendText(int *pRc, char *zIn, const char *zFmt, ...){
  va_list ap;
  char *zAppend = 0;
  char *zRet = 0;
  int nIn = zIn ? STRLEN(zIn) : 0;
  int nAppend = 0;
  va_start(ap, zFmt);
  if( *pRc==SQLITE_OK ){
    zAppend = sqlite3_vmprintf(zFmt, ap);
    if( zAppend ){
      nAppend = STRLEN(zAppend);
      zRet = (char*)sqlite3_malloc(nIn + nAppend + 1);
    }
    if( zAppend && zRet ){
      if( nIn ) memcpy(zRet, zIn, nIn);
      memcpy(&zRet[nIn], zAppend, nAppend+1);
    }else{
      sqlite3_free(zRet);
      zRet = 0;
      *pRc = SQLITE_NOMEM;
    }
    sqlite3_free(zAppend);
    sqlite3_free(zIn);
  }
  va_end(ap);
  return zRet;
}

/*
** Return true if zId must be quoted in order to use it as an SQL
** identifier, or false otherwise.
*/
static int idxIdentifierRequiresQuotes(const char *zId){
  int i;
  for(i=0; zId[i]; i++){
    if( !(zId[i]=='_')
     && !(zId[i]>='0' && zId[i]<='9')
     && !(zId[i]>='a' && zId[i]<='z')
     && !(zId[i]>='A' && zId[i]<='Z')
    ){
      return 1;
    }
  }
  return 0;
}

/*
** This function appends an index column definition suitable for constraint
** pCons to the string passed as zIn and returns the result.
*/
static char *idxAppendColDefn(
  int *pRc,                       /* IN/OUT: Error code */
  char *zIn,                      /* Column defn accumulated so far */
  IdxTable *pTab,                 /* Table index will be created on */
  IdxConstraint *pCons
){
  char *zRet = zIn;
  IdxColumn *p = &pTab->aCol[pCons->iCol];
  if( zRet ) zRet = idxAppendText(pRc, zRet, ", ");

  if( idxIdentifierRequiresQuotes(p->zName) ){
    zRet = idxAppendText(pRc, zRet, "%Q", p->zName);
  }else{
    zRet = idxAppendText(pRc, zRet, "%s", p->zName);
  }

  if( sqlite3_stricmp(p->zColl, pCons->zColl) ){
    if( idxIdentifierRequiresQuotes(pCons->zColl) ){
      zRet = idxAppendText(pRc, zRet, " COLLATE %Q", pCons->zColl);
    }else{
      zRet = idxAppendText(pRc, zRet, " COLLATE %s", pCons->zColl);
    }
  }

  if( pCons->bDesc ){
    zRet = idxAppendText(pRc, zRet, " DESC");
  }
  return zRet;
}

/*
** Search database dbm for an index compatible with the one idxCreateFromCons()
** would create from arguments pScan, pEq and pTail. If no error occurs and 
** such an index is found, return non-zero. Or, if no such index is found,
** return zero.
**
** If an error occurs, set *pRc to an SQLite error code and return zero.
*/
static int idxFindCompatible(
  int *pRc,                       /* OUT: Error code */
  sqlite3* dbm,                   /* Database to search */
  IdxScan *pScan,                 /* Scan for table to search for index on */
  IdxConstraint *pEq,             /* List of == constraints */
  IdxConstraint *pTail            /* List of range constraints */
){
  const char *zTbl = pScan->pTab->zName;
  sqlite3_stmt *pIdxList = 0;
  IdxConstraint *pIter;
  int nEq = 0;                    /* Number of elements in pEq */
  int rc;

  /* Count the elements in list pEq */
  for(pIter=pEq; pIter; pIter=pIter->pLink) nEq++;

  rc = idxPrintfPrepareStmt(dbm, &pIdxList, 0, "PRAGMA index_list=%Q", zTbl);
  while( rc==SQLITE_OK && sqlite3_step(pIdxList)==SQLITE_ROW ){
    int bMatch = 1;
    IdxConstraint *pT = pTail;
    sqlite3_stmt *pInfo = 0;
    const char *zIdx = (const char*)sqlite3_column_text(pIdxList, 1);

    /* Zero the IdxConstraint.bFlag values in the pEq list */
    for(pIter=pEq; pIter; pIter=pIter->pLink) pIter->bFlag = 0;

    rc = idxPrintfPrepareStmt(dbm, &pInfo, 0, "PRAGMA index_xInfo=%Q", zIdx);
    while( rc==SQLITE_OK && sqlite3_step(pInfo)==SQLITE_ROW ){
      int iIdx = sqlite3_column_int(pInfo, 0);
      int iCol = sqlite3_column_int(pInfo, 1);
      const char *zColl = (const char*)sqlite3_column_text(pInfo, 4);

      if( iIdx<nEq ){
        for(pIter=pEq; pIter; pIter=pIter->pLink){
          if( pIter->bFlag ) continue;
          if( pIter->iCol!=iCol ) continue;
          if( sqlite3_stricmp(pIter->zColl, zColl) ) continue;
          pIter->bFlag = 1;
          break;
        }
        if( pIter==0 ){
          bMatch = 0;
          break;
        }
      }else{
        if( pT ){
          if( pT->iCol!=iCol || sqlite3_stricmp(pT->zColl, zColl) ){
            bMatch = 0;
            break;
          }
          pT = pT->pLink;
        }
      }
    }
    idxFinalize(&rc, pInfo);

    if( rc==SQLITE_OK && bMatch ){
      sqlite3_finalize(pIdxList);
      return 1;
    }
  }
  idxFinalize(&rc, pIdxList);

  *pRc = rc;
  return 0;
}

static int idxCreateFromCons(
  sqlite3expert *p,
  IdxScan *pScan,
  IdxConstraint *pEq, 
  IdxConstraint *pTail
){
  sqlite3 *dbm = p->dbm;
  int rc = SQLITE_OK;
  if( (pEq || pTail) && 0==idxFindCompatible(&rc, dbm, pScan, pEq, pTail) ){
    IdxTable *pTab = pScan->pTab;
    char *zCols = 0;
    char *zIdx = 0;
    IdxConstraint *pCons;
    unsigned int h = 0;
    const char *zFmt;

    for(pCons=pEq; pCons; pCons=pCons->pLink){
      zCols = idxAppendColDefn(&rc, zCols, pTab, pCons);
    }
    for(pCons=pTail; pCons; pCons=pCons->pLink){
      zCols = idxAppendColDefn(&rc, zCols, pTab, pCons);
    }

    if( rc==SQLITE_OK ){
      /* Hash the list of columns to come up with a name for the index */
      const char *zTable = pScan->pTab->zName;
      char *zName;                /* Index name */
      int i;
      for(i=0; zCols[i]; i++){
        h += ((h<<3) + zCols[i]);
      }
      zName = sqlite3_mprintf("%s_idx_%08x", zTable, h);
      if( zName==0 ){ 
        rc = SQLITE_NOMEM;
      }else{
        if( idxIdentifierRequiresQuotes(zTable) ){
          zFmt = "CREATE INDEX '%q' ON %Q(%s)";
        }else{
          zFmt = "CREATE INDEX %s ON %s(%s)";
        }
        zIdx = sqlite3_mprintf(zFmt, zName, zTable, zCols);
        if( !zIdx ){
          rc = SQLITE_NOMEM;
        }else{
          rc = sqlite3_exec(dbm, zIdx, 0, 0, p->pzErrmsg);
          idxHashAdd(&rc, &p->hIdx, zName, zIdx);
        }
        sqlite3_free(zName);
        sqlite3_free(zIdx);
      }
    }

    sqlite3_free(zCols);
  }
  return rc;
}

/*
** Return true if list pList (linked by IdxConstraint.pLink) contains
** a constraint compatible with *p. Otherwise return false.
*/
static int idxFindConstraint(IdxConstraint *pList, IdxConstraint *p){
  IdxConstraint *pCmp;
  for(pCmp=pList; pCmp; pCmp=pCmp->pLink){
    if( p->iCol==pCmp->iCol ) return 1;
  }
  return 0;
}

static int idxCreateFromWhere(
  sqlite3expert *p, 
  IdxScan *pScan,                 /* Create indexes for this scan */
  IdxConstraint *pTail            /* range/ORDER BY constraints for inclusion */
){
  IdxConstraint *p1 = 0;
  IdxConstraint *pCon;
  int rc;

  /* Gather up all the == constraints. */
  for(pCon=pScan->pEq; pCon; pCon=pCon->pNext){
    if( !idxFindConstraint(p1, pCon) && !idxFindConstraint(pTail, pCon) ){
      pCon->pLink = p1;
      p1 = pCon;
    }
  }

  /* Create an index using the == constraints collected above. And the
  ** range constraint/ORDER BY terms passed in by the caller, if any. */
  rc = idxCreateFromCons(p, pScan, p1, pTail);

  /* If no range/ORDER BY passed by the caller, create a version of the
  ** index for each range constraint.  */
  if( pTail==0 ){
    for(pCon=pScan->pRange; rc==SQLITE_OK && pCon; pCon=pCon->pNext){
      assert( pCon->pLink==0 );
      if( !idxFindConstraint(p1, pCon) && !idxFindConstraint(pTail, pCon) ){
        rc = idxCreateFromCons(p, pScan, p1, pCon);
      }
    }
  }

  return rc;
}

/*
** Create candidate indexes in database [dbm] based on the data in 
** linked-list pScan.
*/
static int idxCreateCandidates(sqlite3expert *p, char **pzErr){
  int rc = SQLITE_OK;
  IdxScan *pIter;

  for(pIter=p->pScan; pIter && rc==SQLITE_OK; pIter=pIter->pNextScan){
    rc = idxCreateFromWhere(p, pIter, 0);
    if( rc==SQLITE_OK && pIter->pOrder ){
      rc = idxCreateFromWhere(p, pIter, pIter->pOrder);
    }
  }

  return rc;
}

/*
** Free all elements of the linked list starting at pConstraint.
*/
static void idxConstraintFree(IdxConstraint *pConstraint){
  IdxConstraint *pNext;
  IdxConstraint *p;

  for(p=pConstraint; p; p=pNext){
    pNext = p->pNext;
    sqlite3_free(p);
  }
}

/*
** Free all elements of the linked list starting from pScan up until pLast
** (pLast is not freed).
*/
static void idxScanFree(IdxScan *pScan, IdxScan *pLast){
  IdxScan *p;
  IdxScan *pNext;
  for(p=pScan; p!=pLast; p=pNext){
    pNext = p->pNextScan;
    idxConstraintFree(p->pOrder);
    idxConstraintFree(p->pEq);
    idxConstraintFree(p->pRange);
    sqlite3_free(p);
  }
}

/*
** Free all elements of the linked list starting from pStatement up 
** until pLast (pLast is not freed).
*/
static void idxStatementFree(IdxStatement *pStatement, IdxStatement *pLast){
  IdxStatement *p;
  IdxStatement *pNext;
  for(p=pStatement; p!=pLast; p=pNext){
    pNext = p->pNext;
    sqlite3_free(p->zEQP);
    sqlite3_free(p->zIdx);
    sqlite3_free(p);
  }
}

/*
** Free the linked list of IdxTable objects starting at pTab.
*/
static void idxTableFree(IdxTable *pTab){
  IdxTable *pIter;
  IdxTable *pNext;
  for(pIter=pTab; pIter; pIter=pNext){
    pNext = pIter->pNext;
    sqlite3_free(pIter);
  }
}

/*
** Free the linked list of IdxWrite objects starting at pTab.
*/
static void idxWriteFree(IdxWrite *pTab){
  IdxWrite *pIter;
  IdxWrite *pNext;
  for(pIter=pTab; pIter; pIter=pNext){
    pNext = pIter->pNext;
    sqlite3_free(pIter);
  }
}



/*
** This function is called after candidate indexes have been created. It
** runs all the queries to see which indexes they prefer, and populates
** IdxStatement.zIdx and IdxStatement.zEQP with the results.
*/
int idxFindIndexes(
  sqlite3expert *p,
  char **pzErr                         /* OUT: Error message (sqlite3_malloc) */
){
  IdxStatement *pStmt;
  sqlite3 *dbm = p->dbm;
  int rc = SQLITE_OK;

  IdxHash hIdx;
  idxHashInit(&hIdx);

  for(pStmt=p->pStatement; rc==SQLITE_OK && pStmt; pStmt=pStmt->pNext){
    IdxHashEntry *pEntry;
    sqlite3_stmt *pExplain = 0;
    idxHashClear(&hIdx);
    rc = idxPrintfPrepareStmt(dbm, &pExplain, pzErr,
        "EXPLAIN QUERY PLAN %s", pStmt->zSql
    );
    while( rc==SQLITE_OK && sqlite3_step(pExplain)==SQLITE_ROW ){
      int iSelectid = sqlite3_column_int(pExplain, 0);
      int iOrder = sqlite3_column_int(pExplain, 1);
      int iFrom = sqlite3_column_int(pExplain, 2);
      const char *zDetail = (const char*)sqlite3_column_text(pExplain, 3);
      int nDetail = STRLEN(zDetail);
      int i;

      for(i=0; i<nDetail; i++){
        const char *zIdx = 0;
        if( memcmp(&zDetail[i], " USING INDEX ", 13)==0 ){
          zIdx = &zDetail[i+13];
        }else if( memcmp(&zDetail[i], " USING COVERING INDEX ", 22)==0 ){
          zIdx = &zDetail[i+22];
        }
        if( zIdx ){
          const char *zSql;
          int nIdx = 0;
          while( zIdx[nIdx]!='\0' && (zIdx[nIdx]!=' ' || zIdx[nIdx+1]!='(') ){
            nIdx++;
          }
          zSql = idxHashSearch(&p->hIdx, zIdx, nIdx);
          if( zSql ){
            idxHashAdd(&rc, &hIdx, zSql, 0);
            if( rc ) goto find_indexes_out;
          }
          break;
        }
      }

      pStmt->zEQP = idxAppendText(&rc, pStmt->zEQP, "%d|%d|%d|%s\n", 
          iSelectid, iOrder, iFrom, zDetail
      );
    }

    for(pEntry=hIdx.pFirst; pEntry; pEntry=pEntry->pNext){
      pStmt->zIdx = idxAppendText(&rc, pStmt->zIdx, "%s;\n", pEntry->zKey);
    }

    idxFinalize(&rc, pExplain);
  }

 find_indexes_out:
  idxHashClear(&hIdx);
  return rc;
}

static int idxAuthCallback(
  void *pCtx,
  int eOp,
  const char *z3,
  const char *z4,
  const char *zDb,
  const char *zTrigger
){
  int rc = SQLITE_OK;
  if( eOp==SQLITE_INSERT || eOp==SQLITE_UPDATE || eOp==SQLITE_DELETE ){
    if( sqlite3_stricmp(zDb, "main")==0 ){
      sqlite3expert *p = (sqlite3expert*)pCtx;
      IdxTable *pTab;
      for(pTab=p->pTable; pTab; pTab=pTab->pNext){
        if( 0==sqlite3_stricmp(z3, pTab->zName) ) break;
      }
      if( pTab ){
        IdxWrite *pWrite;
        for(pWrite=p->pWrite; pWrite; pWrite=pWrite->pNext){
          if( pWrite->pTab==pTab && pWrite->eOp==eOp ) break;
        }
        if( pWrite==0 ){
          pWrite = idxMalloc(&rc, sizeof(IdxWrite));
          if( rc==SQLITE_OK ){
            pWrite->pTab = pTab;
            pWrite->eOp = eOp;
            pWrite->pNext = p->pWrite;
            p->pWrite = pWrite;
          }
        }
      }
    }
  }
  return rc;
}

static int idxProcessOneTrigger(
  sqlite3expert *p, 
  IdxWrite *pWrite, 
  char **pzErr
){
  static const char *zInt = UNIQUE_TABLE_NAME;
  static const char *zDrop = "DROP TABLE " UNIQUE_TABLE_NAME;
  IdxTable *pTab = pWrite->pTab;
  const char *zTab = pTab->zName;
  const char *zSql = 
    "SELECT 'CREATE TEMP' || substr(sql, 7) FROM sqlite_master "
    "WHERE tbl_name = %Q AND type IN ('table', 'trigger') "
    "ORDER BY type;";
  sqlite3_stmt *pSelect = 0;
  int rc = SQLITE_OK;
  char *zWrite = 0;

  /* Create the table and its triggers in the temp schema */
  rc = idxPrintfPrepareStmt(p->db, &pSelect, pzErr, zSql, zTab, zTab);
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pSelect) ){
    const char *zCreate = (const char*)sqlite3_column_text(pSelect, 0);
    rc = sqlite3_exec(p->dbv, zCreate, 0, 0, pzErr);
  }
  idxFinalize(&rc, pSelect);

  /* Rename the table in the temp schema to zInt */
  if( rc==SQLITE_OK ){
    char *z = sqlite3_mprintf("ALTER TABLE temp.%Q RENAME TO %Q", zTab, zInt);
    if( z==0 ){
      rc = SQLITE_NOMEM;
    }else{
      rc = sqlite3_exec(p->dbv, z, 0, 0, pzErr);
      sqlite3_free(z);
    }
  }

  switch( pWrite->eOp ){
    case SQLITE_INSERT: {
      int i;
      zWrite = idxAppendText(&rc, zWrite, "INSERT INTO %Q VALUES(", zInt);
      for(i=0; i<pTab->nCol; i++){
        zWrite = idxAppendText(&rc, zWrite, "%s?", i==0 ? "" : ", ");
      }
      zWrite = idxAppendText(&rc, zWrite, ")");
      break;
    }
    case SQLITE_UPDATE: {
      int i;
      zWrite = idxAppendText(&rc, zWrite, "UPDATE %Q SET ", zInt);
      for(i=0; i<pTab->nCol; i++){
        zWrite = idxAppendText(&rc, zWrite, "%s%Q=?", i==0 ? "" : ", ", 
            pTab->aCol[i].zName
        );
      }
      break;
    }
    default: {
      assert( pWrite->eOp==SQLITE_DELETE );
      if( rc==SQLITE_OK ){
        zWrite = sqlite3_mprintf("DELETE FROM %Q", zInt);
        if( zWrite==0 ) rc = SQLITE_NOMEM;
      }
    }
  }

  if( rc==SQLITE_OK ){
    sqlite3_stmt *pX = 0;
    rc = sqlite3_prepare_v2(p->dbv, zWrite, -1, &pX, 0);
    idxFinalize(&rc, pX);
    if( rc!=SQLITE_OK ){
      idxDatabaseError(p->dbv, pzErr);
    }
  }
  sqlite3_free(zWrite);

  if( rc==SQLITE_OK ){
    rc = sqlite3_exec(p->dbv, zDrop, 0, 0, pzErr);
  }

  return rc;
}

static int idxProcessTriggers(sqlite3expert *p, char **pzErr){
  int rc = SQLITE_OK;
  IdxWrite *pEnd = 0;
  IdxWrite *pFirst = p->pWrite;

  while( rc==SQLITE_OK && pFirst!=pEnd ){
    IdxWrite *pIter;
    for(pIter=pFirst; rc==SQLITE_OK && pIter!=pEnd; pIter=pIter->pNext){
      rc = idxProcessOneTrigger(p, pIter, pzErr);
    }
    pEnd = pFirst;
    pFirst = p->pWrite;
  }

  return rc;
}


static int idxCreateVtabSchema(sqlite3expert *p, char **pzErrmsg){
  int rc = idxRegisterVtab(p);
  sqlite3_stmt *pSchema = 0;

  /* For each table in the main db schema:
  **
  **   1) Add an entry to the p->pTable list, and
  **   2) Create the equivalent virtual table in dbv.
  */
  rc = idxPrepareStmt(p->db, &pSchema, pzErrmsg,
      "SELECT type, name, sql, 1 FROM sqlite_master "
      "WHERE type IN ('table','view') AND name NOT LIKE 'sqlite_%%' "
      " UNION ALL "
      "SELECT type, name, sql, 2 FROM sqlite_master "
      "WHERE type = 'trigger'"
      "  AND tbl_name IN(SELECT name FROM sqlite_master WHERE type = 'view') "
      "ORDER BY 4, 1"
  );
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pSchema) ){
    const char *zType = (const char*)sqlite3_column_text(pSchema, 0);
    const char *zName = (const char*)sqlite3_column_text(pSchema, 1);
    const char *zSql = (const char*)sqlite3_column_text(pSchema, 2);

    if( zType[0]=='v' || zType[1]=='r' ){
      rc = sqlite3_exec(p->dbv, zSql, 0, 0, pzErrmsg);
    }else{
      IdxTable *pTab;
      rc = idxGetTableInfo(p->db, zName, &pTab, pzErrmsg);
      if( rc==SQLITE_OK ){
        int i;
        char *zInner = 0;
        char *zOuter = 0;
        pTab->pNext = p->pTable;
        p->pTable = pTab;

        /* The statement the vtab will pass to sqlite3_declare_vtab() */
        zInner = idxAppendText(&rc, 0, "CREATE TABLE x(");
        for(i=0; i<pTab->nCol; i++){
          zInner = idxAppendText(&rc, zInner, "%s%Q COLLATE %s", 
              (i==0 ? "" : ", "), pTab->aCol[i].zName, pTab->aCol[i].zColl
          );
        }
        zInner = idxAppendText(&rc, zInner, ")");

        /* The CVT statement to create the vtab */
        zOuter = idxAppendText(&rc, 0, 
            "CREATE VIRTUAL TABLE %Q USING expert(%Q)", zName, zInner
        );
        if( rc==SQLITE_OK ){
          rc = sqlite3_exec(p->dbv, zOuter, 0, 0, pzErrmsg);
        }
        sqlite3_free(zInner);
        sqlite3_free(zOuter);
      }
    }
  }
  idxFinalize(&rc, pSchema);
  return rc;
}

struct IdxSampleCtx {
  int iTarget;
  double target;                  /* Target nRet/nRow value */
  double nRow;                    /* Number of rows seen */
  double nRet;                    /* Number of rows returned */
};

static void idxSampleFunc(
  sqlite3_context *pCtx,
  int argc,
  sqlite3_value **argv
){
  struct IdxSampleCtx *p = (struct IdxSampleCtx*)sqlite3_user_data(pCtx);
  int bRet;

  assert( argc==0 );
  if( p->nRow==0.0 ){
    bRet = 1;
  }else{
    bRet = (p->nRet / p->nRow) <= p->target;
    if( bRet==0 ){
      unsigned short rnd;
      sqlite3_randomness(2, (void*)&rnd);
      bRet = ((int)rnd % 100) <= p->iTarget;
    }
  }

  sqlite3_result_int(pCtx, bRet);
  p->nRow += 1.0;
  p->nRet += (double)bRet;
}

struct IdxRemCtx {
  int nSlot;
  struct IdxRemSlot {
    int eType;                    /* SQLITE_NULL, INTEGER, REAL, TEXT, BLOB */
    i64 iVal;                     /* SQLITE_INTEGER value */
    double rVal;                  /* SQLITE_FLOAT value */
    int nByte;                    /* Bytes of space allocated at z */
    int n;                        /* Size of buffer z */
    char *z;                      /* SQLITE_TEXT/BLOB value */
  } aSlot[1];
};

/*
** Implementation of scalar function rem().
*/
static void idxRemFunc(
  sqlite3_context *pCtx,
  int argc,
  sqlite3_value **argv
){
  struct IdxRemCtx *p = (struct IdxRemCtx*)sqlite3_user_data(pCtx);
  struct IdxRemSlot *pSlot;
  int iSlot;
  assert( argc==2 );

  iSlot = sqlite3_value_int(argv[0]);
  assert( iSlot<=p->nSlot );
  pSlot = &p->aSlot[iSlot];

  switch( pSlot->eType ){
    case SQLITE_NULL:
      /* no-op */
      break;

    case SQLITE_INTEGER:
      sqlite3_result_int64(pCtx, pSlot->iVal);
      break;

    case SQLITE_FLOAT:
      sqlite3_result_double(pCtx, pSlot->rVal);
      break;

    case SQLITE_BLOB:
      sqlite3_result_blob(pCtx, pSlot->z, pSlot->n, SQLITE_TRANSIENT);
      break;

    case SQLITE_TEXT:
      sqlite3_result_text(pCtx, pSlot->z, pSlot->n, SQLITE_TRANSIENT);
      break;
  }

  pSlot->eType = sqlite3_value_type(argv[1]);
  switch( pSlot->eType ){
    case SQLITE_NULL:
      /* no-op */
      break;

    case SQLITE_INTEGER:
      pSlot->iVal = sqlite3_value_int64(argv[1]);
      break;

    case SQLITE_FLOAT:
      pSlot->rVal = sqlite3_value_double(argv[1]);
      break;

    case SQLITE_BLOB:
    case SQLITE_TEXT: {
      int nByte = sqlite3_value_bytes(argv[1]);
      if( nByte>pSlot->nByte ){
        char *zNew = (char*)sqlite3_realloc(pSlot->z, nByte*2);
        if( zNew==0 ){
          sqlite3_result_error_nomem(pCtx);
          return;
        }
        pSlot->nByte = nByte*2;
        pSlot->z = zNew;
      }
      pSlot->n = nByte;
      if( pSlot->eType==SQLITE_BLOB ){
        memcpy(pSlot->z, sqlite3_value_blob(argv[1]), nByte);
      }else{
        memcpy(pSlot->z, sqlite3_value_text(argv[1]), nByte);
      }
      break;
    }
  }
}

static int idxLargestIndex(sqlite3 *db, int *pnMax, char **pzErr){
  int rc = SQLITE_OK;
  const char *zMax = 
    "SELECT max(i.seqno) FROM "
    "  sqlite_master AS s, "
    "  pragma_index_list(s.name) AS l, "
    "  pragma_index_info(l.name) AS i "
    "WHERE s.type = 'table'";
  sqlite3_stmt *pMax = 0;

  *pnMax = 0;
  rc = idxPrepareStmt(db, &pMax, pzErr, zMax);
  if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pMax) ){
    *pnMax = sqlite3_column_int(pMax, 0) + 1;
  }
  idxFinalize(&rc, pMax);

  return rc;
}

static int idxPopulateOneStat1(
  sqlite3expert *p,
  sqlite3_stmt *pIndexXInfo,
  sqlite3_stmt *pWriteStat,
  const char *zTab,
  const char *zIdx,
  char **pzErr
){
  char *zCols = 0;
  char *zOrder = 0;
  char *zQuery = 0;
  int nCol = 0;
  int i;
  sqlite3_stmt *pQuery = 0;
  int *aStat = 0;
  int rc = SQLITE_OK;

  assert( p->iSample>0 );

  /* Formulate the query text */
  sqlite3_bind_text(pIndexXInfo, 1, zIdx, -1, SQLITE_STATIC);
  while( SQLITE_OK==rc && SQLITE_ROW==sqlite3_step(pIndexXInfo) ){
    const char *zComma = zCols==0 ? "" : ", ";
    const char *zName = (const char*)sqlite3_column_text(pIndexXInfo, 0);
    const char *zColl = (const char*)sqlite3_column_text(pIndexXInfo, 1);
    zCols = idxAppendText(&rc, zCols, 
        "%sx.%Q IS rem(%d, x.%Q) COLLATE %s", zComma, zName, nCol, zName, zColl
    );
    zOrder = idxAppendText(&rc, zOrder, "%s%d", zComma, ++nCol);
  }
  sqlite3_reset(pIndexXInfo);
  if( rc==SQLITE_OK ){
    if( p->iSample==100 ){
      zQuery = sqlite3_mprintf(
          "SELECT %s FROM %Q x ORDER BY %s", zCols, zTab, zOrder
      );
    }else{
      zQuery = sqlite3_mprintf(
          "SELECT %s FROM temp."UNIQUE_TABLE_NAME" x ORDER BY %s", zCols, zOrder
      );
    }
  }
  sqlite3_free(zCols);
  sqlite3_free(zOrder);

  /* Formulate the query text */
  if( rc==SQLITE_OK ){
    sqlite3 *dbrem = (p->iSample==100 ? p->db : p->dbv);
    rc = idxPrepareStmt(dbrem, &pQuery, pzErr, zQuery);
  }
  sqlite3_free(zQuery);

  if( rc==SQLITE_OK ){
    aStat = (int*)idxMalloc(&rc, sizeof(int)*(nCol+1));
  }
  if( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pQuery) ){
    IdxHashEntry *pEntry;
    char *zStat = 0;
    for(i=0; i<=nCol; i++) aStat[i] = 1;
    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pQuery) ){
      aStat[0]++;
      for(i=0; i<nCol; i++){
        if( sqlite3_column_int(pQuery, i)==0 ) break;
      }
      for(/*no-op*/; i<nCol; i++){
        aStat[i+1]++;
      }
    }

    if( rc==SQLITE_OK ){
      int s0 = aStat[0];
      zStat = sqlite3_mprintf("%d", s0);
      if( zStat==0 ) rc = SQLITE_NOMEM;
      for(i=1; rc==SQLITE_OK && i<=nCol; i++){
        zStat = idxAppendText(&rc, zStat, " %d", (s0+aStat[i]/2) / aStat[i]);
      }
    }

    if( rc==SQLITE_OK ){
      sqlite3_bind_text(pWriteStat, 1, zTab, -1, SQLITE_STATIC);
      sqlite3_bind_text(pWriteStat, 2, zIdx, -1, SQLITE_STATIC);
      sqlite3_bind_text(pWriteStat, 3, zStat, -1, SQLITE_STATIC);
      sqlite3_step(pWriteStat);
      rc = sqlite3_reset(pWriteStat);
    }

    pEntry = idxHashFind(&p->hIdx, zIdx, STRLEN(zIdx));
    if( pEntry ){
      assert( pEntry->zVal2==0 );
      pEntry->zVal2 = zStat;
    }else{
      sqlite3_free(zStat);
    }
  }
  sqlite3_free(aStat);
  idxFinalize(&rc, pQuery);

  return rc;
}

static int idxBuildSampleTable(sqlite3expert *p, const char *zTab){
  int rc;
  char *zSql;

  rc = sqlite3_exec(p->dbv,"DROP TABLE IF EXISTS temp."UNIQUE_TABLE_NAME,0,0,0);
  if( rc!=SQLITE_OK ) return rc;

  zSql = sqlite3_mprintf(
      "CREATE TABLE temp." UNIQUE_TABLE_NAME " AS SELECT * FROM %Q", zTab
  );
  if( zSql==0 ) return SQLITE_NOMEM;
  rc = sqlite3_exec(p->dbv, zSql, 0, 0, 0);
  sqlite3_free(zSql);

  return rc;
}

/*
** This function is called as part of sqlite3_expert_analyze(). Candidate
** indexes have already been created in database sqlite3expert.dbm, this
** function populates sqlite_stat1 table in the same database.
**
** The stat1 data is generated by querying the 
*/
static int idxPopulateStat1(sqlite3expert *p, char **pzErr){
  int rc = SQLITE_OK;
  int nMax =0;
  struct IdxRemCtx *pCtx = 0;
  struct IdxSampleCtx samplectx; 
  int i;
  i64 iPrev = -100000;
  sqlite3_stmt *pAllIndex = 0;
  sqlite3_stmt *pIndexXInfo = 0;
  sqlite3_stmt *pWrite = 0;

  const char *zAllIndex =
    "SELECT s.rowid, s.name, l.name FROM "
    "  sqlite_master AS s, "
    "  pragma_index_list(s.name) AS l "
    "WHERE s.type = 'table'";
  const char *zIndexXInfo = 
    "SELECT name, coll FROM pragma_index_xinfo(?) WHERE key";
  const char *zWrite = "INSERT INTO sqlite_stat1 VALUES(?, ?, ?)";

  /* If iSample==0, no sqlite_stat1 data is required. */
  if( p->iSample==0 ) return SQLITE_OK;

  rc = idxLargestIndex(p->dbm, &nMax, pzErr);
  if( nMax<=0 || rc!=SQLITE_OK ) return rc;

  rc = sqlite3_exec(p->dbm, "ANALYZE; PRAGMA writable_schema=1", 0, 0, 0);

  if( rc==SQLITE_OK ){
    int nByte = sizeof(struct IdxRemCtx) + (sizeof(struct IdxRemSlot) * nMax);
    pCtx = (struct IdxRemCtx*)idxMalloc(&rc, nByte);
  }

  if( rc==SQLITE_OK ){
    sqlite3 *dbrem = (p->iSample==100 ? p->db : p->dbv);
    rc = sqlite3_create_function(
        dbrem, "rem", 2, SQLITE_UTF8, (void*)pCtx, idxRemFunc, 0, 0
    );
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(
        p->db, "sample", 0, SQLITE_UTF8, (void*)&samplectx, idxSampleFunc, 0, 0
    );
  }

  if( rc==SQLITE_OK ){
    pCtx->nSlot = nMax+1;
    rc = idxPrepareStmt(p->dbm, &pAllIndex, pzErr, zAllIndex);
  }
  if( rc==SQLITE_OK ){
    rc = idxPrepareStmt(p->dbm, &pIndexXInfo, pzErr, zIndexXInfo);
  }
  if( rc==SQLITE_OK ){
    rc = idxPrepareStmt(p->dbm, &pWrite, pzErr, zWrite);
  }

  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pAllIndex) ){
    i64 iRowid = sqlite3_column_int64(pAllIndex, 0);
    const char *zTab = (const char*)sqlite3_column_text(pAllIndex, 1);
    const char *zIdx = (const char*)sqlite3_column_text(pAllIndex, 2);
    if( p->iSample<100 && iPrev!=iRowid ){
      samplectx.target = (double)p->iSample / 100.0;
      samplectx.iTarget = p->iSample;
      samplectx.nRow = 0.0;
      samplectx.nRet = 0.0;
      rc = idxBuildSampleTable(p, zTab);
      if( rc!=SQLITE_OK ) break;
    }
    rc = idxPopulateOneStat1(p, pIndexXInfo, pWrite, zTab, zIdx, pzErr);
    iPrev = iRowid;
  }
  if( rc==SQLITE_OK && p->iSample<100 ){
    rc = sqlite3_exec(p->dbv, 
        "DROP TABLE IF EXISTS temp." UNIQUE_TABLE_NAME, 0,0,0
    );
  }

  idxFinalize(&rc, pAllIndex);
  idxFinalize(&rc, pIndexXInfo);
  idxFinalize(&rc, pWrite);

  for(i=0; i<pCtx->nSlot; i++){
    sqlite3_free(pCtx->aSlot[i].z);
  }
  sqlite3_free(pCtx);

  if( rc==SQLITE_OK ){
    rc = sqlite3_exec(p->dbm, "ANALYZE sqlite_master", 0, 0, 0);
  }

  sqlite3_exec(p->db, "DROP TABLE IF EXISTS temp."UNIQUE_TABLE_NAME,0,0,0);
  return rc;
}

/*
** Allocate a new sqlite3expert object.
*/
sqlite3expert *sqlite3_expert_new(sqlite3 *db, char **pzErrmsg){
  int rc = SQLITE_OK;
  sqlite3expert *pNew;

  pNew = (sqlite3expert*)idxMalloc(&rc, sizeof(sqlite3expert));

  /* Open two in-memory databases to work with. The "vtab database" (dbv)
  ** will contain a virtual table corresponding to each real table in
  ** the user database schema, and a copy of each view. It is used to
  ** collect information regarding the WHERE, ORDER BY and other clauses
  ** of the user's query.
  */
  if( rc==SQLITE_OK ){
    pNew->db = db;
    pNew->iSample = 100;
    rc = sqlite3_open(":memory:", &pNew->dbv);
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_open(":memory:", &pNew->dbm);
    if( rc==SQLITE_OK ){
      sqlite3_db_config(pNew->dbm, SQLITE_DBCONFIG_TRIGGER_EQP, 1, (int*)0);
    }
  }
  

  /* Copy the entire schema of database [db] into [dbm]. */
  if( rc==SQLITE_OK ){
    sqlite3_stmt *pSql;
    rc = idxPrintfPrepareStmt(pNew->db, &pSql, pzErrmsg, 
        "SELECT sql FROM sqlite_master WHERE name NOT LIKE 'sqlite_%%'"
        " AND sql NOT LIKE 'CREATE VIRTUAL %%'"
    );
    while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pSql) ){
      const char *zSql = (const char*)sqlite3_column_text(pSql, 0);
      rc = sqlite3_exec(pNew->dbm, zSql, 0, 0, pzErrmsg);
    }
    idxFinalize(&rc, pSql);
  }

  /* Create the vtab schema */
  if( rc==SQLITE_OK ){
    rc = idxCreateVtabSchema(pNew, pzErrmsg);
  }

  /* Register the auth callback with dbv */
  if( rc==SQLITE_OK ){
    sqlite3_set_authorizer(pNew->dbv, idxAuthCallback, (void*)pNew);
  }

  /* If an error has occurred, free the new object and reutrn NULL. Otherwise,
  ** return the new sqlite3expert handle.  */
  if( rc!=SQLITE_OK ){
    sqlite3_expert_destroy(pNew);
    pNew = 0;
  }
  return pNew;
}

/*
** Configure an sqlite3expert object.
*/
int sqlite3_expert_config(sqlite3expert *p, int op, ...){
  int rc = SQLITE_OK;
  va_list ap;
  va_start(ap, op);
  switch( op ){
    case EXPERT_CONFIG_SAMPLE: {
      int iVal = va_arg(ap, int);
      if( iVal<0 ) iVal = 0;
      if( iVal>100 ) iVal = 100;
      p->iSample = iVal;
      break;
    }
    default:
      rc = SQLITE_NOTFOUND;
      break;
  }

  va_end(ap);
  return rc;
}

/*
** Add an SQL statement to the analysis.
*/
int sqlite3_expert_sql(
  sqlite3expert *p,               /* From sqlite3_expert_new() */
  const char *zSql,               /* SQL statement to add */
  char **pzErr                    /* OUT: Error message (if any) */
){
  IdxScan *pScanOrig = p->pScan;
  IdxStatement *pStmtOrig = p->pStatement;
  int rc = SQLITE_OK;
  const char *zStmt = zSql;

  if( p->bRun ) return SQLITE_MISUSE;

  while( rc==SQLITE_OK && zStmt && zStmt[0] ){
    sqlite3_stmt *pStmt = 0;
    rc = sqlite3_prepare_v2(p->dbv, zStmt, -1, &pStmt, &zStmt);
    if( rc==SQLITE_OK ){
      if( pStmt ){
        IdxStatement *pNew;
        const char *z = sqlite3_sql(pStmt);
        int n = STRLEN(z);
        pNew = (IdxStatement*)idxMalloc(&rc, sizeof(IdxStatement) + n+1);
        if( rc==SQLITE_OK ){
          pNew->zSql = (char*)&pNew[1];
          memcpy(pNew->zSql, z, n+1);
          pNew->pNext = p->pStatement;
          if( p->pStatement ) pNew->iId = p->pStatement->iId+1;
          p->pStatement = pNew;
        }
        sqlite3_finalize(pStmt);
      }
    }else{
      idxDatabaseError(p->dbv, pzErr);
    }
  }

  if( rc!=SQLITE_OK ){
    idxScanFree(p->pScan, pScanOrig);
    idxStatementFree(p->pStatement, pStmtOrig);
    p->pScan = pScanOrig;
    p->pStatement = pStmtOrig;
  }

  return rc;
}

int sqlite3_expert_analyze(sqlite3expert *p, char **pzErr){
  int rc;
  IdxHashEntry *pEntry;

  /* Do trigger processing to collect any extra IdxScan structures */
  rc = idxProcessTriggers(p, pzErr);

  /* Create candidate indexes within the in-memory database file */
  if( rc==SQLITE_OK ){
    rc = idxCreateCandidates(p, pzErr);
  }

  /* Generate the stat1 data */
  if( rc==SQLITE_OK ){
    rc = idxPopulateStat1(p, pzErr);
  }

  /* Formulate the EXPERT_REPORT_CANDIDATES text */
  for(pEntry=p->hIdx.pFirst; pEntry; pEntry=pEntry->pNext){
    p->zCandidates = idxAppendText(&rc, p->zCandidates, 
        "%s;%s%s\n", pEntry->zVal, 
        pEntry->zVal2 ? " -- stat1: " : "", pEntry->zVal2
    );
  }

  /* Figure out which of the candidate indexes are preferred by the query
  ** planner and report the results to the user.  */
  if( rc==SQLITE_OK ){
    rc = idxFindIndexes(p, pzErr);
  }

  if( rc==SQLITE_OK ){
    p->bRun = 1;
  }
  return rc;
}

/*
** Return the total number of statements that have been added to this
** sqlite3expert using sqlite3_expert_sql().
*/
int sqlite3_expert_count(sqlite3expert *p){
  int nRet = 0;
  if( p->pStatement ) nRet = p->pStatement->iId+1;
  return nRet;
}

/*
** Return a component of the report.
*/
const char *sqlite3_expert_report(sqlite3expert *p, int iStmt, int eReport){
  const char *zRet = 0;
  IdxStatement *pStmt;

  if( p->bRun==0 ) return 0;
  for(pStmt=p->pStatement; pStmt && pStmt->iId!=iStmt; pStmt=pStmt->pNext);
  switch( eReport ){
    case EXPERT_REPORT_SQL:
      if( pStmt ) zRet = pStmt->zSql;
      break;
    case EXPERT_REPORT_INDEXES:
      if( pStmt ) zRet = pStmt->zIdx;
      break;
    case EXPERT_REPORT_PLAN:
      if( pStmt ) zRet = pStmt->zEQP;
      break;
    case EXPERT_REPORT_CANDIDATES:
      zRet = p->zCandidates;
      break;
  }
  return zRet;
}

/*
** Free an sqlite3expert object.
*/
void sqlite3_expert_destroy(sqlite3expert *p){
  if( p ){
    sqlite3_close(p->dbm);
    sqlite3_close(p->dbv);
    idxScanFree(p->pScan, 0);
    idxStatementFree(p->pStatement, 0);
    idxTableFree(p->pTable);
    idxWriteFree(p->pWrite);
    idxHashClear(&p->hIdx);
    sqlite3_free(p->zCandidates);
    sqlite3_free(p);
  }
}

#endif /* ifndef SQLITE_OMIT_VIRTUAL_TABLE */

/*
** 2017 April 07
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
*/


#include "sqlite3.h"

typedef struct sqlite3expert sqlite3expert;

/*
** Create a new sqlite3expert object.
**
** If successful, a pointer to the new object is returned and (*pzErr) set
** to NULL. Or, if an error occurs, NULL is returned and (*pzErr) set to
** an English-language error message. In this case it is the responsibility
** of the caller to eventually free the error message buffer using
** sqlite3_free().
*/
sqlite3expert *sqlite3_expert_new(sqlite3 *db, char **pzErr);

/*
** Configure an sqlite3expert object.
**
** EXPERT_CONFIG_SAMPLE:
**   By default, sqlite3_expert_analyze() generates sqlite_stat1 data for
**   each candidate index. This involves scanning and sorting the entire
**   contents of each user database table once for each candidate index
**   associated with the table. For large databases, this can be 
**   prohibitively slow. This option allows the sqlite3expert object to
**   be configured so that sqlite_stat1 data is instead generated based on a
**   subset of each table, or so that no sqlite_stat1 data is used at all.
**
**   A single integer argument is passed to this option. If the value is less
**   than or equal to zero, then no sqlite_stat1 data is generated or used by
**   the analysis - indexes are recommended based on the database schema only.
**   Or, if the value is 100 or greater, complete sqlite_stat1 data is
**   generated for each candidate index (this is the default). Finally, if the
**   value falls between 0 and 100, then it represents the percentage of user
**   table rows that should be considered when generating sqlite_stat1 data.
**
**   Examples:
**
**     // Do not generate any sqlite_stat1 data
**     sqlite3_expert_config(pExpert, EXPERT_CONFIG_SAMPLE, 0);
**
**     // Generate sqlite_stat1 data based on 10% of the rows in each table.
**     sqlite3_expert_config(pExpert, EXPERT_CONFIG_SAMPLE, 10);
*/
int sqlite3_expert_config(sqlite3expert *p, int op, ...);

#define EXPERT_CONFIG_SAMPLE 1    /* int */

/*
** Specify zero or more SQL statements to be included in the analysis.
**
** Buffer zSql must contain zero or more complete SQL statements. This
** function parses all statements contained in the buffer and adds them
** to the internal list of statements to analyze. If successful, SQLITE_OK
** is returned and (*pzErr) set to NULL. Or, if an error occurs - for example
** due to a error in the SQL - an SQLite error code is returned and (*pzErr)
** may be set to point to an English language error message. In this case
** the caller is responsible for eventually freeing the error message buffer
** using sqlite3_free().
**
** If an error does occur while processing one of the statements in the
** buffer passed as the second argument, none of the statements in the
** buffer are added to the analysis.
**
** This function must be called before sqlite3_expert_analyze(). If a call
** to this function is made on an sqlite3expert object that has already
** been passed to sqlite3_expert_analyze() SQLITE_MISUSE is returned
** immediately and no statements are added to the analysis.
*/
int sqlite3_expert_sql(
  sqlite3expert *p,               /* From a successful sqlite3_expert_new() */
  const char *zSql,               /* SQL statement(s) to add */
  char **pzErr                    /* OUT: Error message (if any) */
);


/*
** This function is called after the sqlite3expert object has been configured
** with all SQL statements using sqlite3_expert_sql() to actually perform
** the analysis. Once this function has been called, it is not possible to
** add further SQL statements to the analysis.
**
** If successful, SQLITE_OK is returned and (*pzErr) is set to NULL. Or, if
** an error occurs, an SQLite error code is returned and (*pzErr) set to 
** point to a buffer containing an English language error message. In this
** case it is the responsibility of the caller to eventually free the buffer
** using sqlite3_free().
**
** If an error does occur within this function, the sqlite3expert object
** is no longer useful for any purpose. At that point it is no longer
** possible to add further SQL statements to the object or to re-attempt
** the analysis. The sqlite3expert object must still be freed using a call
** sqlite3_expert_destroy().
*/
int sqlite3_expert_analyze(sqlite3expert *p, char **pzErr);

/*
** Return the total number of statements loaded using sqlite3_expert_sql().
** The total number of SQL statements may be different from the total number
** to calls to sqlite3_expert_sql().
*/
int sqlite3_expert_count(sqlite3expert*);

/*
** Return a component of the report.
**
** This function is called after sqlite3_expert_analyze() to extract the
** results of the analysis. Each call to this function returns either a
** NULL pointer or a pointer to a buffer containing a nul-terminated string.
** The value passed as the third argument must be one of the EXPERT_REPORT_*
** #define constants defined below.
**
** For some EXPERT_REPORT_* parameters, the buffer returned contains 
** information relating to a specific SQL statement. In these cases that
** SQL statement is identified by the value passed as the second argument.
** SQL statements are numbered from 0 in the order in which they are parsed.
** If an out-of-range value (less than zero or equal to or greater than the
** value returned by sqlite3_expert_count()) is passed as the second argument
** along with such an EXPERT_REPORT_* parameter, NULL is always returned.
**
** EXPERT_REPORT_SQL:
**   Return the text of SQL statement iStmt.
**
** EXPERT_REPORT_INDEXES:
**   Return a buffer containing the CREATE INDEX statements for all recommended
**   indexes for statement iStmt. If there are no new recommeded indexes, NULL 
**   is returned.
**
** EXPERT_REPORT_PLAN:
**   Return a buffer containing the EXPLAIN QUERY PLAN output for SQL query
**   iStmt after the proposed indexes have been added to the database schema.
**
** EXPERT_REPORT_CANDIDATES:
**   Return a pointer to a buffer containing the CREATE INDEX statements 
**   for all indexes that were tested (for all SQL statements). The iStmt
**   parameter is ignored for EXPERT_REPORT_CANDIDATES calls.
*/
const char *sqlite3_expert_report(sqlite3expert*, int iStmt, int eReport);

/*
** Values for the third argument passed to sqlite3_expert_report().
*/
#define EXPERT_REPORT_SQL        1
#define EXPERT_REPORT_INDEXES    2
#define EXPERT_REPORT_PLAN       3
#define EXPERT_REPORT_CANDIDATES 4

/*
** Free an (sqlite3expert*) handle and all associated resources. There 
** should be one call to this function for each successful call to 
** sqlite3-expert_new().
*/
void sqlite3_expert_destroy(sqlite3expert*);

/*
** 2017 April 07
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
*/

#if defined(SQLITE_TEST)

#include "sqlite3expert.h"
#include <assert.h>
#include <string.h>

#if defined(INCLUDE_SQLITE_TCL_H)
#  include "sqlite_tcl.h"
#else
#  include "tcl.h"
#  ifndef SQLITE_TCLAPI
#    define SQLITE_TCLAPI
#  endif
#endif

#ifndef SQLITE_OMIT_VIRTUALTABLE

/*
** Extract an sqlite3* db handle from the object passed as the second
** argument. If successful, set *pDb to point to the db handle and return
** TCL_OK. Otherwise, return TCL_ERROR.
*/
static int dbHandleFromObj(Tcl_Interp *interp, Tcl_Obj *pObj, sqlite3 **pDb){
  Tcl_CmdInfo info;
  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(pObj), &info) ){
    Tcl_AppendResult(interp, "no such handle: ", Tcl_GetString(pObj), 0);
    return TCL_ERROR;
  }

  *pDb = *(sqlite3 **)info.objClientData;
  return TCL_OK;
}


/*
** Tclcmd:  $expert sql SQL
**          $expert analyze
**          $expert count
**          $expert report STMT EREPORT
**          $expert destroy
*/
static int SQLITE_TCLAPI testExpertCmd(
  void *clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3expert *pExpert = (sqlite3expert*)clientData;
  struct Subcmd {
    const char *zSub;
    int nArg;
    const char *zMsg;
  } aSub[] = {
    { "sql",       1, "TABLE",        }, /* 0 */
    { "analyze",   0, "",             }, /* 1 */
    { "count",     0, "",             }, /* 2 */
    { "report",    2, "STMT EREPORT", }, /* 3 */
    { "destroy",   0, "",             }, /* 4 */
    { 0 }
  };
  int iSub;
  int rc = TCL_OK;
  char *zErr = 0;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
  rc = Tcl_GetIndexFromObjStruct(interp, 
      objv[1], aSub, sizeof(aSub[0]), "sub-command", 0, &iSub
  );
  if( rc!=TCL_OK ) return rc;
  if( objc!=2+aSub[iSub].nArg ){
    Tcl_WrongNumArgs(interp, 2, objv, aSub[iSub].zMsg);
    return TCL_ERROR;
  }

  switch( iSub ){
    case 0: {      /* sql */
      char *zArg = Tcl_GetString(objv[2]);
      rc = sqlite3_expert_sql(pExpert, zArg, &zErr);
      break;
    }

    case 1: {      /* analyze */
      rc = sqlite3_expert_analyze(pExpert, &zErr);
      break;
    }

    case 2: {      /* count */
      int n = sqlite3_expert_count(pExpert);
      Tcl_SetObjResult(interp, Tcl_NewIntObj(n));
      break;
    }

    case 3: {      /* report */
      const char *aEnum[] = {
        "sql", "indexes", "plan", "candidates", 0
      };
      int iEnum;
      int iStmt;
      const char *zReport;

      if( Tcl_GetIntFromObj(interp, objv[2], &iStmt) 
       || Tcl_GetIndexFromObj(interp, objv[3], aEnum, "report", 0, &iEnum)
      ){
        return TCL_ERROR;
      }

      assert( EXPERT_REPORT_SQL==1 );
      assert( EXPERT_REPORT_INDEXES==2 );
      assert( EXPERT_REPORT_PLAN==3 );
      assert( EXPERT_REPORT_CANDIDATES==4 );
      zReport = sqlite3_expert_report(pExpert, iStmt, 1+iEnum);
      Tcl_SetObjResult(interp, Tcl_NewStringObj(zReport, -1));
      break;
    }

    default:       /* destroy */
      assert( iSub==4 );     
      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
      break;
  }

  if( rc!=TCL_OK ){
    if( zErr ){
      Tcl_SetObjResult(interp, Tcl_NewStringObj(zErr, -1));
    }else{
      extern const char *sqlite3ErrName(int);
      Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
    }
  }
  sqlite3_free(zErr);
  return rc;
}

static void SQLITE_TCLAPI testExpertDel(void *clientData){
  sqlite3expert *pExpert = (sqlite3expert*)clientData;
  sqlite3_expert_destroy(pExpert);
}

/*
** sqlite3_expert_new DB
*/
static int SQLITE_TCLAPI test_sqlite3_expert_new(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  static int iCmd = 0;
  sqlite3 *db;
  char *zCmd = 0;
  char *zErr = 0;
  sqlite3expert *pExpert;
  int rc = TCL_OK;

  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB");
    return TCL_ERROR;
  }
  if( dbHandleFromObj(interp, objv[1], &db) ){
    return TCL_ERROR;
  }

  zCmd = sqlite3_mprintf("sqlite3expert%d", ++iCmd);
  if( zCmd==0 ){
    Tcl_AppendResult(interp, "out of memory", (char*)0);
    return TCL_ERROR;
  }

  pExpert = sqlite3_expert_new(db, &zErr);
  if( pExpert==0 ){
    Tcl_AppendResult(interp, zErr, (char*)0);
    rc = TCL_ERROR;
  }else{
    void *p = (void*)pExpert;
    Tcl_CreateObjCommand(interp, zCmd, testExpertCmd, p, testExpertDel);
    Tcl_SetObjResult(interp, Tcl_NewStringObj(zCmd, -1));
  }

  sqlite3_free(zCmd);
  sqlite3_free(zErr);
  return rc;
}

#endif  /* ifndef SQLITE_OMIT_VIRTUALTABLE */

int TestExpert_Init(Tcl_Interp *interp){
#ifndef SQLITE_OMIT_VIRTUALTABLE
  struct Cmd {
    const char *zCmd;
    Tcl_ObjCmdProc *xProc;
  } aCmd[] = {
    { "sqlite3_expert_new", test_sqlite3_expert_new },
  };
  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(struct Cmd); i++){
    struct Cmd *p = &aCmd[i];
    Tcl_CreateObjCommand(interp, p->zCmd, p->xProc, 0, 0);
  }
#endif
  return TCL_OK;
}

#endif

    if( (iAdj+nToken)>nDocsize ) iAdj = nDocsize - nToken;
    if( iAdj<0 ) iAdj = 0;
    *piPos = iAdj;
  }

  return rc;
}

/*
** Return the value in pVal interpreted as utf-8 text. Except, if pVal 
** contains a NULL value, return a pointer to a static string zero
** bytes in length instead of a NULL pointer.
*/
static const char *fts5ValueToText(sqlite3_value *pVal){
  const char *zRet = (const char*)sqlite3_value_text(pVal);
  return zRet ? zRet : "";
}

/*
** Implementation of snippet() function.
*/
static void fts5SnippetFunction(
  const Fts5ExtensionApi *pApi,   /* API offered by current FTS version */
  Fts5Context *pFts,              /* First arg to pass to pApi functions */

    sqlite3_result_error(pCtx, zErr, -1);
    return;
  }

  nCol = pApi->xColumnCount(pFts);
  memset(&ctx, 0, sizeof(HighlightContext));
  iCol = sqlite3_value_int(apVal[0]);
  ctx.zOpen = fts5ValueToText(apVal[1]);
  ctx.zClose = fts5ValueToText(apVal[2]);
  zEllips = fts5ValueToText(apVal[3]);
  nToken = sqlite3_value_int(apVal[4]);

  iBestCol = (iCol>=0 ? iCol : 0);
  nPhrase = pApi->xPhraseCount(pFts);
  aSeen = sqlite3_malloc(nPhrase);
  if( aSeen==0 ){
    rc = SQLITE_NOMEM;

  if( p2->n ){
    i64 iLastRowid = 0;
    Fts5DoclistIter i1;
    Fts5DoclistIter i2;
    Fts5Buffer out = {0, 0, 0};
    Fts5Buffer tmp = {0, 0, 0};

    /* The maximum size of the output is equal to the sum of the two 
    ** input sizes + 1 varint (9 bytes). The extra varint is because if the
    ** first rowid in one input is a large negative number, and the first in
    ** the other a non-negative number, the delta for the non-negative
    ** number will be larger on disk than the literal integer value
    ** was.  */
    if( sqlite3Fts5BufferSize(&p->rc, &out, p1->n + p2->n + 9) ) return;
    fts5DoclistIterInit(p1, &i1);
    fts5DoclistIterInit(p2, &i2);

    while( 1 ){
      if( i1.iRowid<i2.iRowid ){
        /* Copy entry from i1 */
        fts5MergeAppendDocid(&out, iLastRowid, i1.iRowid);

      fts5MergeAppendDocid(&out, iLastRowid, i1.iRowid);
      fts5BufferSafeAppendBlob(&out, i1.aPoslist, i1.aEof - i1.aPoslist);
    }
    else if( i2.aPoslist ){
      fts5MergeAppendDocid(&out, iLastRowid, i2.iRowid);
      fts5BufferSafeAppendBlob(&out, i2.aPoslist, i2.aEof - i2.aPoslist);
    }
    assert( out.n<=(p1->n+p2->n+9) );

    fts5BufferSet(&p->rc, p1, out.n, out.p);
    fts5BufferFree(&tmp);
    fts5BufferFree(&out);
  }
}

      rc = p->pApi->xSetAuxdata(p->pFts, (void*)((char*)0 + iVal), 0);
      break;
    }
    CASE(15, "xGetAuxdataInt") {
      int iVal;
      int bClear;
      if( Tcl_GetBooleanFromObj(interp, objv[2], &bClear) ) return TCL_ERROR;
      iVal = (int)((char*)p->pApi->xGetAuxdata(p->pFts, bClear) - (char*)0);
      Tcl_SetObjResult(interp, Tcl_NewIntObj(iVal));
      break;
    }

    CASE(16, "xPhraseForeach") {
      int iPhrase;
      int iCol;

    'x a a a a a a a a a a',
    'a a a a a a a a a a a a a a a a a a a x'
  );
}
do_execsql_test 5.1 {
  SELECT snippet(p1, 0, '[', ']', '...', 6) FROM p1('x');
} {{[x] a a a a a...}}

do_execsql_test 5.2 {
  SELECT snippet(p1, 0, '[', ']', NULL, 6) FROM p1('x');
} {{[x] a a a a a}}
do_execsql_test 5.3 {
  SELECT snippet(p1, 0, NULL, ']', '...', 6) FROM p1('x');
} {{x] a a a a a...}}
do_execsql_test 5.4 {
  SELECT snippet(p1, 0, '[', NULL, '...', 6) FROM p1('x');
} {{[x a a a a a...}}

} ;# foreach_detail_mode 

finish_test

    foreach x [list bbb ddd fff hhh jjj lll nnn ppp rrr ttt] {
      set doc [string repeat "$x " 30]
      execsql { INSERT INTO t1 VALUES($doc) }
    }
    execsql COMMIT
  } {}

  do_execsql_test 2.$tn.2 {
    INSERT INTO t1(t1) VALUES('integrity-check');
  }

  set ret 1
  foreach x [list a c e g i k m o q s u] {
    do_execsql_test 2.$tn.3.$ret {
      SELECT rowid FROM t1 WHERE t1 MATCH $x || '*';
    } {}
    incr ret
  }
}

reset_db
do_execsql_test 3.0 {
  CREATE VIRTUAL TABLE x1 USING fts5(a);
  INSERT INTO x1(rowid, a) VALUES(-1000000000000, 'toyota');
  INSERT INTO x1(rowid, a) VALUES(1, 'tarago');
}
do_execsql_test 3.1 {
  SELECT rowid FROM x1('t*');
} {-1000000000000 1}


finish_test

**
**   * Integration of ICU and SQLite collation sequences.
**
**   * An implementation of the LIKE operator that uses ICU to 
**     provide case-independent matching.
*/

#if !defined(SQLITE_CORE)                  \
 || defined(SQLITE_ENABLE_ICU)             \
 || defined(SQLITE_ENABLE_ICU_COLLATIONS)

/* Include ICU headers */
#include <unicode/utypes.h>
#include <unicode/uregex.h>
#include <unicode/ustring.h>
#include <unicode/ucol.h>

#include <assert.h>

#ifndef SQLITE_CORE
  #include "sqlite3ext.h"
  SQLITE_EXTENSION_INIT1
#else
  #include "sqlite3.h"
#endif

/*
** This function is called when an ICU function called from within
** the implementation of an SQL scalar function returns an error.
**
** The scalar function context passed as the first argument is 
** loaded with an error message based on the following two args.
*/
static void icuFunctionError(
  sqlite3_context *pCtx,       /* SQLite scalar function context */
  const char *zName,           /* Name of ICU function that failed */
  UErrorCode e                 /* Error code returned by ICU function */
){
  char zBuf[128];
  sqlite3_snprintf(128, zBuf, "ICU error: %s(): %s", zName, u_errorName(e));
  zBuf[127] = '\0';
  sqlite3_result_error(pCtx, zBuf, -1);
}

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU)

/*
** Maximum length (in bytes) of the pattern in a LIKE or GLOB
** operator.
*/
#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
#endif

  }

  if( zA && zB ){
    sqlite3_result_int(context, icuLikeCompare(zA, zB, uEsc));
  }
}



















/*
** Function to delete compiled regexp objects. Registered as
** a destructor function with sqlite3_set_auxdata().
*/
static void icuRegexpDelete(void *p){
  URegularExpression *pExpr = (URegularExpression *)p;
  uregex_close(pExpr);

      icuFunctionError(p, bToUpper ? "u_strToUpper" : "u_strToLower", status);
    }
    return;
  }
  assert( 0 );     /* Unreachable */
}

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU) */

/*
** Collation sequence destructor function. The pCtx argument points to
** a UCollator structure previously allocated using ucol_open().
*/
static void icuCollationDel(void *pCtx){
  UCollator *p = (UCollator *)pCtx;
  ucol_close(p);

    const char *zName;                        /* Function name */
    unsigned char nArg;                       /* Number of arguments */
    unsigned short enc;                       /* Optimal text encoding */
    unsigned char iContext;                   /* sqlite3_user_data() context */
    void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
  } scalars[] = {
    {"icu_load_collation",  2, SQLITE_UTF8,                1, icuLoadCollation},
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU)
    {"regexp", 2, SQLITE_ANY|SQLITE_DETERMINISTIC,         0, icuRegexpFunc},
    {"lower",  1, SQLITE_UTF16|SQLITE_DETERMINISTIC,       0, icuCaseFunc16},
    {"lower",  2, SQLITE_UTF16|SQLITE_DETERMINISTIC,       0, icuCaseFunc16},
    {"upper",  1, SQLITE_UTF16|SQLITE_DETERMINISTIC,       1, icuCaseFunc16},
    {"upper",  2, SQLITE_UTF16|SQLITE_DETERMINISTIC,       1, icuCaseFunc16},
    {"lower",  1, SQLITE_UTF8|SQLITE_DETERMINISTIC,        0, icuCaseFunc16},
    {"lower",  2, SQLITE_UTF8|SQLITE_DETERMINISTIC,        0, icuCaseFunc16},
    {"upper",  1, SQLITE_UTF8|SQLITE_DETERMINISTIC,        1, icuCaseFunc16},
    {"upper",  2, SQLITE_UTF8|SQLITE_DETERMINISTIC,        1, icuCaseFunc16},
    {"like",   2, SQLITE_UTF8|SQLITE_DETERMINISTIC,        0, icuLikeFunc},
    {"like",   3, SQLITE_UTF8|SQLITE_DETERMINISTIC,        0, icuLikeFunc},
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU) */
  };
  int rc = SQLITE_OK;
  int i;

  
  for(i=0; rc==SQLITE_OK && i<(int)(sizeof(scalars)/sizeof(scalars[0])); i++){
    const struct IcuScalar *p = &scalars[i];
    rc = sqlite3_create_function(
        db, p->zName, p->nArg, p->enc, 
        p->iContext ? (void*)db : (void*)0,
        p->xFunc, 0, 0

** Functions in wrapper3.c. This file contains the tdb wrapper for lsm.
** The wrapper for lsm is a bit more involved than the others, as it 
** includes code for a couple of different lsm configurations, and for
** various types of fault injection and robustness testing.
*/
int test_lsm_open(const char*, const char *zFile, int bClear, TestDb **ppDb);
int test_lsm_lomem_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_lomem2_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_zip_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_small_open(const char*, const char*, int bClear, TestDb **ppDb);
int test_lsm_mt2(const char*, const char *zFile, int bClear, TestDb **ppDb);
int test_lsm_mt3(const char*, const char *zFile, int bClear, TestDb **ppDb);

int tdb_lsm_configure(lsm_db *, const char *);

  const char *zName;
  const char *zDefaultDb;
  int (*xOpen)(const char *, const char *zFilename, int bClear, TestDb **ppDb);
} aLib[] = {
  { "sqlite3",      "testdb.sqlite",    sql_open },
  { "lsm_small",    "testdb.lsm_small", test_lsm_small_open },
  { "lsm_lomem",    "testdb.lsm_lomem", test_lsm_lomem_open },
  { "lsm_lomem2",   "testdb.lsm_lomem2", test_lsm_lomem2_open },
#ifdef HAVE_ZLIB
  { "lsm_zip",      "testdb.lsm_zip",   test_lsm_zip_open },
#endif
  { "lsm",          "testdb.lsm",       test_lsm_open },
#ifdef LSM_MUTEX_PTHREADS
  { "lsm_mt2",      "testdb.lsm_mt2",   test_lsm_mt2 },
  { "lsm_mt3",      "testdb.lsm_mt3",   test_lsm_mt3 },

  const char *zCfg = 
    "page_size=256 block_size=64 autoflush=16 "
    "autocheckpoint=32"
    "mmap=0 "
  ;
  return testLsmOpen(zCfg, zFilename, bClear, ppDb);
}

int test_lsm_lomem2_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){
    /* "max_freelist=4 autocheckpoint=32" */
  const char *zCfg = 
    "page_size=512 block_size=64 autoflush=0 mmap=0 "
  ;
  return testLsmOpen(zCfg, zFilename, bClear, ppDb);
}

int test_lsm_zip_open(
  const char *zSpec, 
  const char *zFilename, 
  int bClear, 
  TestDb **ppDb
){

typedef unsigned short int u16;
typedef unsigned int u32;
typedef lsm_i64 i64;
typedef unsigned long long int u64;
#endif

/* A page number is a 64-bit integer. */
typedef i64 LsmPgno;

#ifdef LSM_DEBUG
int lsmErrorBkpt(int);
#else
# define lsmErrorBkpt(x) (x)
#endif

  void **apShm;                   /* Shared memory chunks */
  ShmHeader *pShmhdr;             /* Live shared-memory header */
  TreeHeader treehdr;             /* Local copy of tree-header */
  u32 aSnapshot[LSM_META_PAGE_SIZE / sizeof(u32)];
};

struct Segment {
  LsmPgno iFirst;                  /* First page of this run */
  LsmPgno iLastPg;                 /* Last page of this run */
  LsmPgno iRoot;                   /* Root page number (if any) */
  int nSize;                       /* Size of this run in pages */

  Redirect *pRedirect;             /* Block redirects (or NULL) */
};

/*
** iSplitTopic/pSplitKey/nSplitKey:

** access to the associated Level struct.
**
** iOutputOff:
**   The byte offset to write to next within the last page of the 
**   output segment.
*/
struct MergeInput {
  LsmPgno iPg;                    /* Page on which next input is stored */
  int iCell;                      /* Cell containing next input to merge */
};
struct Merge {
  int nInput;                     /* Number of input runs being merged */
  MergeInput *aInput;             /* Array nInput entries in size */
  MergeInput splitkey;            /* Location in file of current splitkey */
  int nSkip;                      /* Number of separators entries to skip */
  int iOutputOff;                 /* Write offset on output page */
  LsmPgno iCurrentPtr;            /* Current pointer value */
};

/* 
** The first argument to this macro is a pointer to a Segment structure.
** Returns true if the structure instance indicates that the separators
** array is valid.
*/

  u32 iCmpId;                     /* Id of compression scheme */
  Level *pLevel;                  /* Pointer to level 0 of snapshot (or NULL) */
  i64 iId;                        /* Snapshot id */
  i64 iLogOff;                    /* Log file offset */
  Redirect redirect;              /* Block redirection array */

  /* Used by worker snapshots only */
  int nBlock;                        /* Number of blocks in database file */
  LsmPgno aiAppend[LSM_APPLIST_SZ];  /* Append point list */
  Freelist freelist;                 /* Free block list */
  u32 nWrite;                        /* Total number of pages written to disk */
};
#define LSM_INITIAL_SNAPSHOT_ID 11

/*
** Functions from file "lsm_ckpt.c".
*/
int lsmCheckpointWrite(lsm_db *, u32 *);

int lsmFsPageSize(FileSystem *);
void lsmFsSetPageSize(FileSystem *, int);

int lsmFsFileid(lsm_db *pDb, void **ppId, int *pnId);

/* Creating, populating, gobbling and deleting sorted runs. */
void lsmFsGobble(lsm_db *, Segment *, LsmPgno *, int);
int lsmFsSortedDelete(FileSystem *, Snapshot *, int, Segment *);
int lsmFsSortedFinish(FileSystem *, Segment *);
int lsmFsSortedAppend(FileSystem *, Snapshot *, Level *, int, Page **);
int lsmFsSortedPadding(FileSystem *, Snapshot *, Segment *);

/* Functions to retrieve the lsm_env pointer from a FileSystem or Page object */
lsm_env *lsmFsEnv(FileSystem *);
lsm_env *lsmPageEnv(Page *);
FileSystem *lsmPageFS(Page *);

int lsmFsSectorSize(FileSystem *);

void lsmSortedSplitkey(lsm_db *, Level *, int *);

/* Reading sorted run content. */
int lsmFsDbPageLast(FileSystem *pFS, Segment *pSeg, Page **ppPg);
int lsmFsDbPageGet(FileSystem *, Segment *, LsmPgno, Page **);
int lsmFsDbPageNext(Segment *, Page *, int eDir, Page **);

u8 *lsmFsPageData(Page *, int *);
int lsmFsPageRelease(Page *);
int lsmFsPagePersist(Page *);
void lsmFsPageRef(Page *);
LsmPgno lsmFsPageNumber(Page *);

int lsmFsNRead(FileSystem *);
int lsmFsNWrite(FileSystem *);

int lsmFsMetaPageGet(FileSystem *, int, int, MetaPage **);
int lsmFsMetaPageRelease(MetaPage *);
u8 *lsmFsMetaPageData(MetaPage *, int *);

#ifdef LSM_DEBUG
int lsmFsDbPageIsLast(Segment *pSeg, Page *pPg);
int lsmFsIntegrityCheck(lsm_db *);
#endif

LsmPgno lsmFsRedirectPage(FileSystem *, Redirect *, LsmPgno);

int lsmFsPageWritable(Page *);

/* Functions to read, write and sync the log file. */
int lsmFsWriteLog(FileSystem *pFS, i64 iOff, LsmString *pStr);
int lsmFsSyncLog(FileSystem *pFS);
int lsmFsReadLog(FileSystem *pFS, i64 iOff, int nRead, LsmString *pStr);
int lsmFsTruncateLog(FileSystem *pFS, i64 nByte);
int lsmFsTruncateDb(FileSystem *pFS, i64 nByte);
int lsmFsCloseAndDeleteLog(FileSystem *pFS);

LsmFile *lsmFsDeferClose(FileSystem *pFS);

/* And to sync the db file */
int lsmFsSyncDb(FileSystem *, int);

void lsmFsFlushWaiting(FileSystem *, int *);

/* Used by lsm_info(ARRAY_STRUCTURE) and lsm_config(MMAP) */
int lsmInfoArrayStructure(lsm_db *pDb, int bBlock, LsmPgno iFirst, char **pz);
int lsmInfoArrayPages(lsm_db *pDb, LsmPgno iFirst, char **pzOut);
int lsmConfigMmap(lsm_db *pDb, int *piParam);

int lsmEnvOpen(lsm_env *, const char *, int, lsm_file **);
int lsmEnvClose(lsm_env *pEnv, lsm_file *pFile);
int lsmEnvLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int eLock);
int lsmEnvTestLock(lsm_env *pEnv, lsm_file *pFile, int iLock, int nLock, int);

int lsmEnvShmMap(lsm_env *, lsm_file *, int, int, void **); 
void lsmEnvShmBarrier(lsm_env *);
void lsmEnvShmUnmap(lsm_env *, lsm_file *, int);

void lsmEnvSleep(lsm_env *, int);

int lsmFsReadSyncedId(lsm_db *db, int, i64 *piVal);

int lsmFsSegmentContainsPg(FileSystem *pFS, Segment *, LsmPgno, int *);

void lsmFsPurgeCache(FileSystem *);

/*
** End of functions from "lsm_file.c".
**************************************************************************/

/* 
** Functions from file "lsm_sorted.c".
*/
int lsmInfoPageDump(lsm_db *, LsmPgno, int, char **);
void lsmSortedCleanup(lsm_db *);
int lsmSortedAutoWork(lsm_db *, int nUnit);

int lsmSortedWalkFreelist(lsm_db *, int, int (*)(void *, int, i64), void *);

int lsmSaveWorker(lsm_db *, int);

static void ckptExportAppendlist(
  lsm_db *db,                     /* Database connection */
  CkptBuffer *p,                  /* Checkpoint buffer to write to */
  int *piOut,                     /* IN/OUT: Offset within checkpoint buffer */
  int *pRc                        /* IN/OUT: Error code */
){
  int i;
  LsmPgno *aiAppend = db->pWorker->aiAppend;

  for(i=0; i<LSM_APPLIST_SZ; i++){
    ckptAppend64(p, piOut, aiAppend[i], pRc);
  }
};

static int ckptExportSnapshot( 

**   The lsmFsSortedAppend() function sets the pSeg pointer to point to the
**   segment that the new page will be a part of. It is unset by
**   lsmFsPagePersist() after the page is written to disk.
*/
struct Page {
  u8 *aData;                      /* Buffer containing page data */
  int nData;                      /* Bytes of usable data at aData[] */
  LsmPgno iPg;                    /* Page number */
  int nRef;                       /* Number of outstanding references */
  int flags;                      /* Combination of PAGE_XXX flags */
  Page *pHashNext;                /* Next page in hash table slot */
  Page *pLruNext;                 /* Next page in LRU list */
  Page *pLruPrev;                 /* Previous page in LRU list */
  FileSystem *pFS;                /* File system that owns this page */

#else
# define IOERR_WRAPPER(rc) (rc)
#endif

#ifdef NDEBUG
# define assert_lists_are_ok(x)
#else
static Page *fsPageFindInHash(FileSystem *pFS, LsmPgno iPg, int *piHash);

static void assert_lists_are_ok(FileSystem *pFS){
#if 0
  Page *p;

  assert( pFS->nMapLimit>=0 );

  return LSM_OK;
}

/*
** Return true if page iReal of the database should be accessed using mmap.
** False otherwise.
*/
static int fsMmapPage(FileSystem *pFS, LsmPgno iReal){
  return ((i64)iReal*pFS->nPagesize <= pFS->nMapLimit);
}

/*
** Given that there are currently nHash slots in the hash table, return 
** the hash key for file iFile, page iPg.
*/
static int fsHashKey(int nHash, LsmPgno iPg){
  return (iPg % nHash);
}

/*
** This is a helper function for lsmFsOpen(). It opens a single file on
** disk (either the database or log file).
*/

** Return the page number of the first page on block iBlock. Blocks are
** numbered starting from 1.
**
** For a compressed database, page numbers are byte offsets. The first
** page on each block is the byte offset immediately following the 4-byte
** "previous block" pointer at the start of each block.
*/
static LsmPgno fsFirstPageOnBlock(FileSystem *pFS, int iBlock){
  LsmPgno iPg;
  if( pFS->pCompress ){
    if( iBlock==1 ){
      iPg = pFS->nMetasize * 2 + 4;
    }else{
      iPg = pFS->nBlocksize * (LsmPgno)(iBlock-1) + 4;
    }
  }else{
    const int nPagePerBlock = (pFS->nBlocksize / pFS->nPagesize);
    if( iBlock==1 ){
      iPg = 1 + ((pFS->nMetasize*2 + pFS->nPagesize - 1) / pFS->nPagesize);
    }else{
      iPg = 1 + (iBlock-1) * nPagePerBlock;
    }
  }
  return iPg;
}

/*
** Return the page number of the last page on block iBlock. Blocks are
** numbered starting from 1.
**
** For a compressed database, page numbers are byte offsets. The first
** page on each block is the byte offset of the byte immediately before 
** the 4-byte "next block" pointer at the end of each block.
*/
static LsmPgno fsLastPageOnBlock(FileSystem *pFS, int iBlock){
  if( pFS->pCompress ){
    return pFS->nBlocksize * (LsmPgno)iBlock - 1 - 4;
  }else{
    const int nPagePerBlock = (pFS->nBlocksize / pFS->nPagesize);
    return iBlock * nPagePerBlock;
  }
}

/*
** Return the block number of the block that page iPg is located on. 
** Blocks are numbered starting from 1.
*/
static int fsPageToBlock(FileSystem *pFS, LsmPgno iPg){
  if( pFS->pCompress ){
    return (int)((iPg / pFS->nBlocksize) + 1);
  }else{
    return (int)(1 + ((iPg-1) / (pFS->nBlocksize / pFS->nPagesize)));
  }
}

/*
** Return true if page iPg is the last page on its block.
**
** This function is only called in non-compressed database mode.
*/
static int fsIsLast(FileSystem *pFS, LsmPgno iPg){
  const int nPagePerBlock = (pFS->nBlocksize / pFS->nPagesize);
  assert( !pFS->pCompress );
  return ( iPg && (iPg % nPagePerBlock)==0 );
}

/*
** Return true if page iPg is the first page on its block.
**
** This function is only called in non-compressed database mode.
*/
static int fsIsFirst(FileSystem *pFS, LsmPgno iPg){
  const int nPagePerBlock = (pFS->nBlocksize / pFS->nPagesize);
  assert( !pFS->pCompress );
  return ( (iPg % nPagePerBlock)==1
        || (iPg<nPagePerBlock && iPg==fsFirstPageOnBlock(pFS, 1))
  );
}

  }
  return pPage->aData;
}

/*
** Return the page number of a page.
*/
LsmPgno lsmFsPageNumber(Page *pPage){
  /* assert( (pPage->flags & PAGE_DIRTY)==0 ); */
  return pPage ? pPage->iPg : 0;
}

/*
** Page pPg is currently part of the LRU list belonging to pFS. Remove
** it from the list. pPg->pLruNext and pPg->pLruPrev are cleared by this

/*
** Search the hash-table for page iPg. If an entry is round, return a pointer
** to it. Otherwise, return NULL.
**
** Either way, if argument piHash is not NULL set *piHash to the hash slot
** number that page iPg would be stored in before returning.
*/
static Page *fsPageFindInHash(FileSystem *pFS, LsmPgno iPg, int *piHash){
  Page *p;                        /* Return value */
  int iHash = fsHashKey(pFS->nHash, iPg);

  if( piHash ) *piHash = iHash;
  for(p=pFS->apHash[iHash]; p; p=p->pHashNext){
    if( p->iPg==iPg) break;
  }

}

/*
** If page iPg has been redirected according to the redirections in the
** object passed as the second argument, return the destination page to
** which it is redirected. Otherwise, return a copy of iPg.
*/
LsmPgno lsmFsRedirectPage(FileSystem *pFS, Redirect *pRedir, LsmPgno iPg){
  LsmPgno iReal = iPg;

  if( pRedir ){
    const int nPagePerBlock = (
        pFS->pCompress ? pFS->nBlocksize : (pFS->nBlocksize / pFS->nPagesize)
    );
    int iBlk = fsPageToBlock(pFS, iPg);
    int i;
    for(i=0; i<pRedir->n; i++){
      int iFrom = pRedir->a[i].iFrom;
      if( iFrom>iBlk ) break;
      if( iFrom==iBlk ){
        int iTo = pRedir->a[i].iTo;
        iReal = iPg - (LsmPgno)(iFrom - iTo) * nPagePerBlock;
        if( iTo==1 ){
          iReal += (fsFirstPageOnBlock(pFS, 1)-1);
        }
        break;
      }
    }
  }

  assert( iReal!=0 );
  return iReal;
}

/* Required by the circular fsBlockNext<->fsPageGet dependency. */
static int fsPageGet(FileSystem *, Segment *, LsmPgno, int, Page **, int *);

/*
** Parameter iBlock is a database file block. This function reads the value 
** stored in the blocks "next block" pointer and stores it in *piNext.
** LSM_OK is returned if everything is successful, or an LSM error code
** otherwise.
*/

  }
  return rc;
}

/*
** Return the page number of the last page on the same block as page iPg.
*/
LsmPgno fsLastPageOnPagesBlock(FileSystem *pFS, LsmPgno iPg){
  return fsLastPageOnBlock(pFS, fsPageToBlock(pFS, iPg));
}

/*
** Read nData bytes of data from offset iOff of the database file into
** buffer aData. If this means reading past the end of a block, follow
** the block pointer to the next block and continue reading.

** to the total number of free bytes before returning.
**
** If no error occurs, LSM_OK is returned. Otherwise, an lsm error code.
*/
static int fsPageGet(
  FileSystem *pFS,                /* File-system handle */
  Segment *pSeg,                  /* Block redirection to use (or NULL) */
  LsmPgno iPg,                    /* Page id */
  int noContent,                  /* True to not load content from disk */
  Page **ppPg,                    /* OUT: New page handle */
  int *pnSpace                    /* OUT: Bytes of free space */
){
  Page *p;
  int iHash;
  int rc = LSM_OK;

  /* In most cases iReal is the same as iPg. Except, if pSeg->pRedirect is 
  ** not NULL, and the block containing iPg has been redirected, then iReal
  ** is the page number after redirection.  */
  LsmPgno iReal = lsmFsRedirectPage(pFS, (pSeg ? pSeg->pRedirect : 0), iPg);

  assert_lists_are_ok(pFS);
  assert( iPg>=fsFirstPageOnBlock(pFS, 1) );
  assert( iReal>=fsFirstPageOnBlock(pFS, 1) );
  *ppPg = 0;

  /* Search the hash-table for the page */

/*
** Return true if the first or last page of segment pRun falls between iFirst
** and iLast, inclusive, and pRun is not equal to pIgnore.
*/
static int fsRunEndsBetween(
  Segment *pRun, 
  Segment *pIgnore, 
  LsmPgno iFirst, 
  LsmPgno iLast
){
  return (pRun!=pIgnore && (
        (pRun->iFirst>=iFirst && pRun->iFirst<=iLast)
     || (pRun->iLastPg>=iFirst && pRun->iLastPg<=iLast)
  ));
}

/*
** Return true if level pLevel contains a segment other than pIgnore for
** which the first or last page is between iFirst and iLast, inclusive.
*/
static int fsLevelEndsBetween(
  Level *pLevel, 
  Segment *pIgnore, 
  LsmPgno iFirst, 
  LsmPgno iLast
){
  int i;

  if( fsRunEndsBetween(&pLevel->lhs, pIgnore, iFirst, iLast) ){
    return 1;
  }
  for(i=0; i<pLevel->nRight; i++){

static int fsFreeBlock(
  FileSystem *pFS,                /* File system object */
  Snapshot *pSnapshot,            /* Worker snapshot */
  Segment *pIgnore,               /* Ignore this run when searching */
  int iBlk                        /* Block number of block to free */
){
  int rc = LSM_OK;                /* Return code */
  LsmPgno iFirst;                 /* First page on block iBlk */
  LsmPgno iLast;                  /* Last page on block iBlk */
  Level *pLevel;                  /* Used to iterate through levels */

  int iIn;                        /* Used to iterate through append points */
  int iOut = 0;                   /* Used to output append points */
  LsmPgno *aApp = pSnapshot->aiAppend;

  iFirst = fsFirstPageOnBlock(pFS, iBlk);
  iLast = fsLastPageOnBlock(pFS, iBlk);

  /* Check if any other run in the snapshot has a start or end page 
  ** within this block. If there is such a run, return early. */
  for(pLevel=lsmDbSnapshotLevel(pSnapshot); pLevel; pLevel=pLevel->pNext){

}

/*
** aPgno is an array containing nPgno page numbers. Return the smallest page
** number from the array that falls on block iBlk. Or, if none of the pages
** in aPgno[] fall on block iBlk, return 0.
*/
static LsmPgno firstOnBlock(
  FileSystem *pFS, 
  int iBlk, 
  LsmPgno *aPgno, 
  int nPgno
){
  LsmPgno iRet = 0;
  int i;
  for(i=0; i<nPgno; i++){
    LsmPgno iPg = aPgno[i];
    if( fsPageToBlock(pFS, iPg)==iBlk && (iRet==0 || iPg<iRet) ){
      iRet = iPg;
    }
  }
  return iRet;
}

#ifndef NDEBUG
/*
** Return true if page iPg, which is a part of segment p, lies on
** a redirected block. 
*/
static int fsPageRedirects(FileSystem *pFS, Segment *p, LsmPgno iPg){
  return (iPg!=0 && iPg!=lsmFsRedirectPage(pFS, p->pRedirect, iPg));
}

/*
** Return true if the second argument is not NULL and any of the first
** last or root pages lie on a redirected block. 
*/

** the segment pRun. This function gobbles from the start of the run to the
** first page that appears in aPgno[] (i.e. so that the aPgno[] entry is
** the new first page of the run).
*/
void lsmFsGobble(
  lsm_db *pDb,
  Segment *pRun, 
  LsmPgno *aPgno,
  int nPgno
){
  int rc = LSM_OK;
  FileSystem *pFS = pDb->pFS;
  Snapshot *pSnapshot = pDb->pWorker;
  int iBlk;

  assert( pRun->nSize>0 );
  assert( 0==fsSegmentRedirects(pFS, pRun) );
  assert( nPgno>0 && 0==fsPageRedirects(pFS, pRun, aPgno[0]) );

  iBlk = fsPageToBlock(pFS, pRun->iFirst);
  pRun->nSize += (int)(pRun->iFirst - fsFirstPageOnBlock(pFS, iBlk));

  while( rc==LSM_OK ){
    int iNext = 0;
    LsmPgno iFirst = firstOnBlock(pFS, iBlk, aPgno, nPgno);
    if( iFirst ){
      pRun->iFirst = iFirst;
      break;
    }
    rc = fsBlockNext(pFS, pRun, iBlk, &iNext);
    if( rc==LSM_OK ) rc = fsFreeBlock(pFS, pSnapshot, pRun, iBlk);
    pRun->nSize -= (int)(

**   *piNext = iPg + nByte;
**
** But take block overflow and redirection into account.
*/
static int fsNextPageOffset(
  FileSystem *pFS,                /* File system object */
  Segment *pSeg,                  /* Segment to move within */
  LsmPgno iPg,                    /* Offset of current page */
  int nByte,                      /* Size of current page including headers */
  LsmPgno *piNext                 /* OUT: Offset of next page. Or zero (EOF) */
){
  LsmPgno iNext;
  int rc;

  assert( pFS->pCompress );

  rc = fsAddOffset(pFS, pSeg, iPg, nByte-1, &iNext);
  if( pSeg && iNext==pSeg->iLastPg ){
    iNext = 0;

** LSM_OK is returned if no error occurs. Otherwise, an lsm error code.
** If any value other than LSM_OK is returned, then the final value of
** *piPrev is undefined.
*/
static int fsGetPageBefore(
  FileSystem *pFS, 
  Segment *pSeg, 
  LsmPgno iPg, 
  LsmPgno *piPrev
){
  u8 aSz[3];
  int rc;
  i64 iRead;

  assert( pFS->pCompress );

**
** Page references returned by this function should be released by the 
** caller using lsmFsPageRelease().
*/
int lsmFsDbPageNext(Segment *pRun, Page *pPg, int eDir, Page **ppNext){
  int rc = LSM_OK;
  FileSystem *pFS = pPg->pFS;
  LsmPgno iPg = pPg->iPg;

  assert( 0==fsSegmentRedirects(pFS, pRun) );
  if( pFS->pCompress ){
    int nSpace = pPg->nCompress + 2*3;

    do {
      if( eDir>0 ){

** already allocated block. If it is possible, the page number of the first
** page to use for the new segment is returned. Otherwise zero.
**
** If argument pLvl is not NULL, then this function will not attempt to
** start the new segment immediately following any segment that is part
** of the right-hand-side of pLvl.
*/
static LsmPgno findAppendPoint(FileSystem *pFS, Level *pLvl){
  int i;
  LsmPgno *aiAppend = pFS->pDb->pWorker->aiAppend;
  LsmPgno iRet = 0;

  for(i=LSM_APPLIST_SZ-1; iRet==0 && i>=0; i--){
    if( (iRet = aiAppend[i]) ){
      if( pLvl ){
        int iBlk = fsPageToBlock(pFS, iRet);
        int j;
        for(j=0; iRet && j<pLvl->nRight; j++){

  Snapshot *pSnapshot,
  Level *pLvl,
  int bDefer,
  Page **ppOut
){
  int rc = LSM_OK;
  Page *pPg = 0;
  LsmPgno iApp = 0;
  LsmPgno iNext = 0;
  Segment *p = &pLvl->lhs;
  LsmPgno iPrev = p->iLastPg;

  *ppOut = 0;
  assert( p->pRedirect==0 );

  if( pFS->pCompress || bDefer ){
    /* In compressed database mode the page is not assigned a page number
    ** or location in the database file at this point. This will be done

    ** Shift this extra block back to the free-block list. 
    **
    ** Otherwise, add the first free page in the last block used by the run
    ** to the lAppend list.
    */
    if( fsLastPageOnPagesBlock(pFS, p->iLastPg)!=p->iLastPg ){
      int i;
      LsmPgno *aiAppend = pFS->pDb->pWorker->aiAppend;
      for(i=0; i<LSM_APPLIST_SZ; i++){
        if( aiAppend[i]==0 ){
          aiAppend[i] = p->iLastPg+1;
          break;
        }
      }
    }else if( pFS->pCompress==0 ){

}

/*
** Obtain a reference to page number iPg.
**
** Return LSM_OK if successful, or an lsm error code if an error occurs.
*/
int lsmFsDbPageGet(FileSystem *pFS, Segment *pSeg, LsmPgno iPg, Page **ppPg){
  return fsPageGet(pFS, pSeg, iPg, 0, ppPg, 0);
}

/*
** Obtain a reference to the last page in the segment passed as the 
** second argument.
**
** Return LSM_OK if successful, or an lsm error code if an error occurs.
*/
int lsmFsDbPageLast(FileSystem *pFS, Segment *pSeg, Page **ppPg){
  int rc;
  LsmPgno iPg = pSeg->iLastPg;
  if( pFS->pCompress ){
    int nSpace;
    iPg++;
    do {
      nSpace = 0;
      rc = fsGetPageBefore(pFS, pSeg, iPg, &iPg);
      if( rc==LSM_OK ){

** number (*piPg) lies on block iFrom, then calculate the equivalent
** page on block iTo and set *piPg to this value before returning.
*/
static void fsMovePage(
  FileSystem *pFS,                /* File system object */
  int iTo,                        /* Destination block */
  int iFrom,                      /* Source block */
  LsmPgno *piPg                   /* IN/OUT: Page number */
){
  LsmPgno iPg = *piPg;
  if( iFrom==fsPageToBlock(pFS, iPg) ){
    const int nPagePerBlock = (
        pFS->pCompress ? pFS ->nBlocksize : (pFS->nBlocksize / pFS->nPagesize)
    );
    *piPg = iPg - (LsmPgno)(iFrom - iTo) * nPagePerBlock;
  }
}

/*
** Copy the contents of block iFrom to block iTo. 
**
** It is safe to assume that there are no outstanding references to pages 

/*
** Append raw data to a segment. Return the database file offset that the
** data is written to (this may be used as the page number if the data
** being appended is a new page record).
**
** This function is only used in compressed database mode.
*/
static LsmPgno fsAppendData(
  FileSystem *pFS,                /* File-system handle */
  Segment *pSeg,                  /* Segment to append to */
  const u8 *aData,                /* Buffer containing data to write */
  int nData,                      /* Size of buffer aData[] in bytes */
  int *pRc                        /* IN/OUT: Error code */
){
  LsmPgno iRet = 0;
  int rc = *pRc;
  assert( pFS->pCompress );
  if( rc==LSM_OK ){
    int nRem = 0;
    int nWrite = 0;
    LsmPgno iLastOnBlock;
    LsmPgno iApp = pSeg->iLastPg+1;

    /* If this is the first data written into the segment, find an append-point
    ** or allocate a new block.  */
    if( iApp==1 ){
      pSeg->iFirst = iApp = findAppendPoint(pFS, 0);
      if( iApp==0 ){
        int iBlk;

          assert( iApp==(fsPageToBlock(pFS, iApp)*pFS->nBlocksize)-4 );
          lsmPutU32(aPtr, iBlk);
          rc = lsmEnvWrite(pFS->pEnv, pFS->fdDb, iApp, aPtr, sizeof(aPtr));
        }

        /* Set the "prev" pointer on the new block */
        if( rc==LSM_OK ){
          LsmPgno iWrite;
          lsmPutU32(aPtr, fsPageToBlock(pFS, iApp));
          iWrite = fsFirstPageOnBlock(pFS, iBlk);
          rc = lsmEnvWrite(pFS->pEnv, pFS->fdDb, iWrite-4, aPtr, sizeof(aPtr));
          if( nRem>0 ) iApp = iWrite;
        }
      }else{
        /* The next block is already allocated. */

** LSM_OK is returned if successful, or an lsm error code otherwise. If
** any value other than LSM_OK is returned, then the final value of all
** output variables is undefined.
*/
static int fsAppendPage(
  FileSystem *pFS, 
  Segment *pSeg,
  LsmPgno *piNew,
  int *piPrev,
  int *piNext
){
  LsmPgno iPrev = pSeg->iLastPg;
  int rc;
  assert( iPrev!=0 );

  *piPrev = 0;
  *piNext = 0;

  if( fsIsLast(pFS, iPrev) ){

  }
  *pRc = rc;
}

/*
** If there exists a hash-table entry associated with page iPg, remove it.
*/
static void fsRemoveHashEntry(FileSystem *pFS, LsmPgno iPg){
  Page *p;
  int iHash = fsHashKey(pFS->nHash, iPg);

  for(p=pFS->apHash[iHash]; p && p->iPg!=iPg; p=p->pHashNext);

  if( p ){
    assert( p->nRef==0 || (p->flags & PAGE_FREE)==0 );

int lsmFsSortedPadding(
  FileSystem *pFS, 
  Snapshot *pSnapshot,
  Segment *pSeg
){
  int rc = LSM_OK;
  if( pFS->pCompress && pSeg->iFirst ){
    LsmPgno iLast2;
    LsmPgno iLast = pSeg->iLastPg;  /* Current last page of segment */
    int nPad;                       /* Bytes of padding required */
    u8 aSz[3];

    iLast2 = (1 + iLast/pFS->szSector) * pFS->szSector - 1;
    assert( fsPageToBlock(pFS, iLast)==fsPageToBlock(pFS, iLast2) );
    nPad = (int)(iLast2 - iLast);

int lsmFsSectorSize(FileSystem *pFS){
  return pFS->szSector;
}

/*
** Helper function for lsmInfoArrayStructure().
*/
static Segment *startsWith(Segment *pRun, LsmPgno iFirst){
  return (iFirst==pRun->iFirst) ? pRun : 0;
}

/*
** Return the segment that starts with page iFirst, if any. If no such segment
** can be found, return NULL.
*/
static Segment *findSegment(Snapshot *pWorker, LsmPgno iFirst){
  Level *pLvl;                    /* Used to iterate through db levels */
  Segment *pSeg = 0;              /* Pointer to segment to return */

  for(pLvl=lsmDbSnapshotLevel(pWorker); pLvl && pSeg==0; pLvl=pLvl->pNext){
    if( 0==(pSeg = startsWith(&pLvl->lhs, iFirst)) ){
      int i;
      for(i=0; i<pLvl->nRight; i++){

** eventually free the string using lsmFree().
**
** If an error occurs, *pzOut is set to NULL and an LSM error code returned.
*/
int lsmInfoArrayStructure(
  lsm_db *pDb, 
  int bBlock,                     /* True for block numbers only */
  LsmPgno iFirst,
  char **pzOut
){
  int rc = LSM_OK;
  Snapshot *pWorker;              /* Worker snapshot */
  Segment *pArray = 0;            /* Array to report on */
  int bUnlock = 0;

  }
  return rc;
}

int lsmFsSegmentContainsPg(
  FileSystem *pFS, 
  Segment *pSeg, 
  LsmPgno iPg, 
  int *pbRes
){
  Redirect *pRedir = pSeg->pRedirect;
  int rc = LSM_OK;
  int iBlk;
  int iLastBlk;
  int iPgBlock;                   /* Block containing page iPg */

** This function implements the lsm_info(LSM_INFO_ARRAY_PAGES) request.
** If successful, *pzOut is set to point to a nul-terminated string 
** containing the array structure and LSM_OK is returned. The caller should
** eventually free the string using lsmFree().
**
** If an error occurs, *pzOut is set to NULL and an LSM error code returned.
*/
int lsmInfoArrayPages(lsm_db *pDb, LsmPgno iFirst, char **pzOut){
  int rc = LSM_OK;
  Snapshot *pWorker;              /* Worker snapshot */
  Segment *pSeg = 0;              /* Array to report on */
  int bUnlock = 0;

  *pzOut = 0;
  if( iFirst==0 ) return LSM_ERROR;

#ifndef NDEBUG
/*
** Return true if pPg happens to be the last page in segment pSeg. Or false
** otherwise. This function is only invoked as part of assert() conditions.
*/
int lsmFsDbPageIsLast(Segment *pSeg, Page *pPg){
  if( pPg->pFS->pCompress ){
    LsmPgno iNext = 0;
    int rc;
    rc = fsNextPageOffset(pPg->pFS, pSeg, pPg->iPg, pPg->nCompress+6, &iNext);
    return (rc!=LSM_OK || iNext==0);
  }
  return (pPg->iPg==pSeg->iLastPg);
}
#endif

    case LSM_INFO_DB_STRUCTURE: {
      char **pzVal = va_arg(ap, char **);
      rc = lsmStructList(pDb, pzVal);
      break;
    }

    case LSM_INFO_ARRAY_STRUCTURE: {
      LsmPgno pgno = va_arg(ap, LsmPgno);
      char **pzVal = va_arg(ap, char **);
      rc = lsmInfoArrayStructure(pDb, 0, pgno, pzVal);
      break;
    }

    case LSM_INFO_ARRAY_PAGES: {
      LsmPgno pgno = va_arg(ap, LsmPgno);
      char **pzVal = va_arg(ap, char **);
      rc = lsmInfoArrayPages(pDb, pgno, pzVal);
      break;
    }

    case LSM_INFO_PAGE_HEX_DUMP:
    case LSM_INFO_PAGE_ASCII_DUMP: {
      LsmPgno pgno = va_arg(ap, LsmPgno);
      char **pzVal = va_arg(ap, char **);
      int bUnlock = 0;
      rc = infoGetWorker(pDb, 0, &bUnlock);
      if( rc==LSM_OK ){
        int bHex = (eParam==LSM_INFO_PAGE_HEX_DUMP);
        rc = lsmInfoPageDump(pDb, pgno, bHex, pzVal);
      }

    int pgsz = lsmFsPageSize(pDb->pFS);
    int nQuant = LSM_AUTOWORK_QUANT * pgsz;
    int nBefore;
    int nAfter;
    int nDiff;

    if( nQuant>pDb->nTreeLimit ){
      nQuant = LSM_MAX(pDb->nTreeLimit, pgsz);
    }

    nBefore = lsmTreeSize(pDb);
    if( bDeleteRange ){
      rc = lsmTreeDelete(pDb, (void *)pKey, nKey, (void *)pVal, nVal);
    }else{
      rc = lsmTreeInsert(pDb, (void *)pKey, nKey, (void *)pVal, nVal);

#ifndef LSM_SEGMENTPTR_FREE_THRESHOLD
# define LSM_SEGMENTPTR_FREE_THRESHOLD 1024
#endif

typedef struct SegmentPtr SegmentPtr;
typedef struct LsmBlob LsmBlob;

struct LsmBlob {
  lsm_env *pEnv;
  void *pData;
  int nData;
  int nAlloc;
};

/*

  Level *pLevel;                /* Level object segment is part of */
  Segment *pSeg;                /* Segment to access */

  /* Current page. See segmentPtrLoadPage(). */
  Page *pPg;                    /* Current page */
  u16 flags;                    /* Copy of page flags field */
  int nCell;                    /* Number of cells on pPg */
  LsmPgno iPtr;                 /* Base cascade pointer */

  /* Current cell. See segmentPtrLoadCell() */
  int iCell;                    /* Current record within page pPg */
  int eType;                    /* Type of current record */
  LsmPgno iPgPtr;               /* Cascade pointer offset */
  void *pKey; int nKey;         /* Key associated with current record */
  void *pVal; int nVal;         /* Current record value (eType==WRITE only) */

  /* Blobs used to allocate buffers for pKey and pVal as required */
  LsmBlob blob1;
  LsmBlob blob2;
};

/*
** Used to iterate through the keys stored in a b-tree hierarchy from start
** to finish. Only First() and Next() operations are required.
**
**   btreeCursorNew()

  int iPg;                        /* Current entry in aPg[]. -1 -> EOF. */
  BtreePg *aPg;                   /* Pages from root to current location */

  /* Cache of current entry. pKey==0 for EOF. */
  void *pKey;
  int nKey;
  int eType;
  LsmPgno iPtr;

  /* Storage for key, if not local */
  LsmBlob blob;
};


/*
** A cursor used for merged searches or iterations through up to one
** Tree structure and any number of sorted files.
**

*/
struct MultiCursor {
  lsm_db *pDb;                    /* Connection that owns this cursor */
  MultiCursor *pNext;             /* Next cursor owned by connection pDb */
  int flags;                      /* Mask of CURSOR_XXX flags */

  int eType;                      /* Cache of current key type */
  LsmBlob key;                    /* Cache of current key (or NULL) */
  LsmBlob val;                    /* Cache of current value */

  /* All the component cursors: */
  TreeCursor *apTreeCsr[2];       /* Up to two tree cursors */
  int iFree;                      /* Next element of free-list (-ve for eof) */
  SegmentPtr *aPtr;               /* Array of segment pointers */
  int nPtr;                       /* Size of array aPtr[] */
  BtreeCursor *pBtCsr;            /* b-tree cursor (db writes only) */

  /* Comparison results */
  int nTree;                      /* Size of aTree[] array */
  int *aTree;                     /* Array of comparison results */

  /* Used by cursors flushing the in-memory tree only */
  void *pSystemVal;               /* Pointer to buffer to free */

  /* Used by worker cursors only */
  LsmPgno *pPrevMergePtr;
};

/*
** The following constants are used to assign integers to each component
** cursor of a multi-cursor.
*/
#define CURSOR_DATA_TREE0     0   /* Current tree cursor (apTreeCsr[0]) */

  lsm_db *pDb;                    /* Database handle */
  Level *pLevel;                  /* Worker snapshot Level being merged */
  MultiCursor *pCsr;              /* Cursor to read new segment contents from */
  int bFlush;                     /* True if this is an in-memory tree flush */
  Hierarchy hier;                 /* B-tree hierarchy under construction */
  Page *pPage;                    /* Current output page */
  int nWork;                      /* Number of calls to mergeWorkerNextPage() */
  LsmPgno *aGobble;               /* Gobble point for each input segment */

  LsmPgno iIndirect;
  struct SavedPgno {
    LsmPgno iPgno;
    int bStore;
  } aSave[2];
};

#ifdef LSM_DEBUG_EXPENSIVE
static int assertPointersOk(lsm_db *, Segment *, Segment *, int);
static int assertBtreeOk(lsm_db *, Segment *);

  aOut[3] = (u8)((nVal>>32) & 0xFF);
  aOut[4] = (u8)((nVal>>24) & 0xFF);
  aOut[5] = (u8)((nVal>>16) & 0xFF);
  aOut[6] = (u8)((nVal>> 8) & 0xFF);
  aOut[7] = (u8)((nVal    ) & 0xFF);
}

static int sortedBlobGrow(lsm_env *pEnv, LsmBlob *pBlob, int nData){
  assert( pBlob->pEnv==pEnv || (pBlob->pEnv==0 && pBlob->pData==0) );
  if( pBlob->nAlloc<nData ){
    pBlob->pData = lsmReallocOrFree(pEnv, pBlob->pData, nData);
    if( !pBlob->pData ) return LSM_NOMEM_BKPT;
    pBlob->nAlloc = nData;
    pBlob->pEnv = pEnv;
  }
  return LSM_OK;
}

static int sortedBlobSet(lsm_env *pEnv, LsmBlob *pBlob, void *pData, int nData){
  if( sortedBlobGrow(pEnv, pBlob, nData) ) return LSM_NOMEM;
  memcpy(pBlob->pData, pData, nData);
  pBlob->nData = nData;
  return LSM_OK;
}

#if 0
static int sortedBlobCopy(LsmBlob *pDest, LsmBlob *pSrc){
  return sortedBlobSet(pDest, pSrc->pData, pSrc->nData);
}
#endif

static void sortedBlobFree(LsmBlob *pBlob){
  assert( pBlob->pEnv || pBlob->pData==0 );
  if( pBlob->pData ) lsmFree(pBlob->pEnv, pBlob->pData);
  memset(pBlob, 0, sizeof(LsmBlob));
}

static int sortedReadData(
  Segment *pSeg,
  Page *pPg,
  int iOff,
  int nByte,
  void **ppData,
  LsmBlob *pBlob
){
  int rc = LSM_OK;
  int iEnd;
  int nData;
  int nCell;
  u8 *aData;

  return rc;
}

static int pageGetNRec(u8 *aData, int nData){
  return (int)lsmGetU16(&aData[SEGMENT_NRECORD_OFFSET(nData)]);
}

static LsmPgno pageGetPtr(u8 *aData, int nData){
  return (LsmPgno)lsmGetU64(&aData[SEGMENT_POINTER_OFFSET(nData)]);
}

static int pageGetFlags(u8 *aData, int nData){
  return (int)lsmGetU16(&aData[SEGMENT_FLAGS_OFFSET(nData)]);
}

static u8 *pageGetCell(u8 *aData, int nData, int iCell){

  return pageGetNRec(aData, nData);
}

/*
** Return the decoded (possibly relative) pointer value stored in cell 
** iCell from page aData/nData.
*/
static LsmPgno pageGetRecordPtr(u8 *aData, int nData, int iCell){
  LsmPgno iRet;                   /* Return value */
  u8 *aCell;                      /* Pointer to cell iCell */

  assert( iCell<pageGetNRec(aData, nData) && iCell>=0 );
  aCell = pageGetCell(aData, nData, iCell);
  lsmVarintGet64(&aCell[1], &iRet);
  return iRet;
}

static u8 *pageGetKey(
  Segment *pSeg,                  /* Segment pPg belongs to */
  Page *pPg,                      /* Page to read from */
  int iCell,                      /* Index of cell on page to read */
  int *piTopic,                   /* OUT: Topic associated with this key */
  int *pnKey,                     /* OUT: Size of key in bytes */
  LsmBlob *pBlob                  /* If required, use this for dynamic memory */
){
  u8 *pKey;
  int nDummy;
  int eType;
  u8 *aData;
  int nData;

static int pageGetKeyCopy(
  lsm_env *pEnv,                  /* Environment handle */
  Segment *pSeg,                  /* Segment pPg belongs to */
  Page *pPg,                      /* Page to read from */
  int iCell,                      /* Index of cell on page to read */
  int *piTopic,                   /* OUT: Topic associated with this key */
  LsmBlob *pBlob                  /* If required, use this for dynamic memory */
){
  int rc = LSM_OK;
  int nKey;
  u8 *aKey;

  aKey = pageGetKey(pSeg, pPg, iCell, piTopic, &nKey, pBlob);
  assert( (void *)aKey!=pBlob->pData || nKey==pBlob->nData );
  if( (void *)aKey!=pBlob->pData ){
    rc = sortedBlobSet(pEnv, pBlob, aKey, nKey);
  }

  return rc;
}

static LsmPgno pageGetBtreeRef(Page *pPg, int iKey){
  LsmPgno iRef;
  u8 *aData;
  int nData;
  u8 *aCell;

  aData = fsPageData(pPg, &nData);
  aCell = pageGetCell(aData, nData, iKey);
  assert( aCell[0]==0 );

#define GETVARINT64(a, i) (((i)=((u8*)(a))[0])<=240?1:lsmVarintGet64((a), &(i)))
#define GETVARINT32(a, i) (((i)=((u8*)(a))[0])<=240?1:lsmVarintGet32((a), &(i)))

static int pageGetBtreeKey(
  Segment *pSeg,                  /* Segment page pPg belongs to */
  Page *pPg,
  int iKey, 
  LsmPgno *piPtr, 
  int *piTopic, 
  void **ppKey,
  int *pnKey,
  LsmBlob *pBlob
){
  u8 *aData;
  int nData;
  u8 *aCell;
  int eType;

  aData = fsPageData(pPg, &nData);
  assert( SEGMENT_BTREE_FLAG & pageGetFlags(aData, nData) );
  assert( iKey>=0 && iKey<pageGetNRec(aData, nData) );

  aCell = pageGetCell(aData, nData, iKey);
  eType = *aCell++;
  aCell += GETVARINT64(aCell, *piPtr);

  if( eType==0 ){
    int rc;
    LsmPgno iRef;               /* Page number of referenced page */
    Page *pRef;
    aCell += GETVARINT64(aCell, iRef);
    rc = lsmFsDbPageGet(lsmPageFS(pPg), pSeg, iRef, &pRef);
    if( rc!=LSM_OK ) return rc;
    pageGetKeyCopy(lsmPageEnv(pPg), pSeg, pRef, 0, &eType, pBlob);
    lsmFsPageRelease(pRef);
    *ppKey = pBlob->pData;

static int btreeCursorLoadKey(BtreeCursor *pCsr){
  int rc = LSM_OK;
  if( pCsr->iPg<0 ){
    pCsr->pKey = 0;
    pCsr->nKey = 0;
    pCsr->eType = 0;
  }else{
    LsmPgno dummy;
    int iPg = pCsr->iPg;
    int iCell = pCsr->aPg[iPg].iCell;
    while( iCell<0 && (--iPg)>=0 ){
      iCell = pCsr->aPg[iPg].iCell-1;
    }
    if( iPg<0 || iCell<0 ) return LSM_CORRUPT_BKPT;

  assert( pCsr->iPg==pCsr->nDepth-1 );

  aData = fsPageData(pPg->pPage, &nData);
  nCell = pageGetNRec(aData, nData);
  assert( pPg->iCell<=nCell );
  pPg->iCell++;
  if( pPg->iCell==nCell ){
    LsmPgno iLoad;

    /* Up to parent. */
    lsmFsPageRelease(pPg->pPage);
    pPg->pPage = 0;
    pCsr->iPg--;
    while( pCsr->iPg>=0 ){
      pPg = &pCsr->aPg[pCsr->iPg];

  MergeInput *p
){
  int rc = LSM_OK;

  if( p->iPg ){
    lsm_env *pEnv = lsmFsEnv(pCsr->pFS);
    int iCell;                    /* Current cell number on leaf page */
    LsmPgno iLeaf;                /* Page number of current leaf page */
    int nDepth;                   /* Depth of b-tree structure */
    Segment *pSeg = pCsr->pSeg;

    /* Decode the MergeInput structure */
    iLeaf = p->iPg;
    nDepth = (p->iCell & 0x00FF);
    iCell = (p->iCell >> 8) - 1;

      pCsr->nDepth = nDepth;
      pCsr->aPg[pCsr->iPg].iCell = iCell;
      rc = lsmFsDbPageGet(pCsr->pFS, pSeg, iLeaf, pp);
    }

    /* Populate any other aPg[] array entries */
    if( rc==LSM_OK && nDepth>1 ){
      LsmBlob blob = {0,0,0};
      void *pSeek;
      int nSeek;
      int iTopicSeek;
      int iPg = 0;
      int iLoad = (int)pSeg->iRoot;
      Page *pPg = pCsr->aPg[nDepth-1].pPage;
 
      if( pageObjGetNRec(pPg)==0 ){
        /* This can happen when pPg is the right-most leaf in the b-tree.
        ** In this case, set the iTopicSeek/pSeek/nSeek key to a value
        ** greater than any real key.  */
        assert( iCell==-1 );
        iTopicSeek = 1000;
        pSeek = 0;
        nSeek = 0;
      }else{
        LsmPgno dummy;
        rc = pageGetBtreeKey(pSeg, pPg,
            0, &dummy, &iTopicSeek, &pSeek, &nSeek, &pCsr->blob
        );
      }

      do {
        Page *pPg2;

          iMax = iCell2-1;
          iMin = 0;

          while( iMax>=iMin ){
            int iTry = (iMin+iMax)/2;
            void *pKey; int nKey;         /* Key for cell iTry */
            int iTopic;                   /* Topic for key pKeyT/nKeyT */
            LsmPgno iPtr;                 /* Pointer for cell iTry */
            int res;                      /* (pSeek - pKeyT) */

            rc = pageGetBtreeKey(
                pSeg, pPg2, iTry, &iPtr, &iTopic, &pKey, &nKey, &blob
            );
            if( rc!=LSM_OK ) break;

      u8 *aData;
      int nData;

      pBtreePg = &pCsr->aPg[pCsr->iPg];
      aData = fsPageData(pBtreePg->pPage, &nData);
      pCsr->iPtr = btreeCursorPtr(aData, nData, pBtreePg->iCell+1);
      if( pBtreePg->iCell<0 ){
        LsmPgno dummy;
        int i;
        for(i=pCsr->iPg-1; i>=0; i--){
          if( pCsr->aPg[i].iCell>0 ) break;
        }
        assert( i>=0 );
        rc = pageGetBtreeKey(pSeg,
            pCsr->aPg[i].pPage, pCsr->aPg[i].iCell-1,

}

static int segmentPtrReadData(
  SegmentPtr *pPtr,
  int iOff,
  int nByte,
  void **ppData,
  LsmBlob *pBlob
){
  return sortedReadData(pPtr->pSeg, pPtr->pPg, iOff, nByte, ppData, pBlob);
}

static int segmentPtrNextPage(
  SegmentPtr *pPtr,              /* Load page into this SegmentPtr object */
  int eDir                       /* +1 for next(), -1 for prev() */

  pSeg = sortedSplitkeySegment(pLevel);
  if( rc==LSM_OK ){
    rc = lsmFsDbPageGet(pDb->pFS, pSeg, pMerge->splitkey.iPg, &pPg);
  }
  if( rc==LSM_OK ){
    int iTopic;
    LsmBlob blob = {0, 0, 0, 0};
    u8 *aData;
    int nData;
  
    aData = lsmFsPageData(pPg, &nData);
    if( pageGetFlags(aData, nData) & SEGMENT_BTREE_FLAG ){
      void *pKey;
      int nKey;
      LsmPgno dummy;
      rc = pageGetBtreeKey(pSeg,
          pPg, pMerge->splitkey.iCell, &dummy, &iTopic, &pKey, &nKey, &blob
      );
      if( rc==LSM_OK && blob.pData!=pKey ){
        rc = sortedBlobSet(pEnv, &blob, pKey, nKey);
      }
    }else{

*/
static int assertKeyLocation(
  MultiCursor *pCsr, 
  SegmentPtr *pPtr, 
  void *pKey, int nKey
){
  lsm_env *pEnv = lsmFsEnv(pCsr->pDb->pFS);
  LsmBlob blob = {0, 0, 0};
  int eDir;
  int iTopic = 0;                 /* TODO: Fix me */

  for(eDir=-1; eDir<=1; eDir+=2){
    Page *pTest = pPtr->pPg;

    lsmFsPageRef(pTest);

  return rc;
}

static int ptrFwdPointer(
  Page *pPage,
  int iCell,
  Segment *pSeg,
  LsmPgno *piPtr,
  int *pbFound
){
  Page *pPg = pPage;
  int iFirst = iCell;
  int rc = LSM_OK;

  do {

**   much better if the multi-cursor could do this lazily - only seek to the
**   level (N+1) page after the user has moved the cursor on level N passed
**   the big range-delete.
*/
static int segmentPtrFwdPointer(
  MultiCursor *pCsr,              /* Multi-cursor pPtr belongs to */
  SegmentPtr *pPtr,               /* Segment-pointer to extract FC ptr from */
  LsmPgno *piPtr                  /* OUT: FC pointer value */
){
  Level *pLvl = pPtr->pLevel;
  Level *pNext = pLvl->pNext;
  Page *pPg = pPtr->pPg;
  int rc;
  int bFound;
  LsmPgno iOut = 0;

  if( pPtr->pSeg==&pLvl->lhs || pPtr->pSeg==&pLvl->aRhs[pLvl->nRight-1] ){
    if( pNext==0 
        || (pNext->nRight==0 && pNext->lhs.iRoot)
        || (pNext->nRight!=0 && pNext->aRhs[0].iRoot)
      ){
      /* Do nothing. The pointer will not be used anyway. */

  int *pbStop
){
  int (*xCmp)(void *, int, void *, int) = pCsr->pDb->xCmp;
  int res = 0;                        /* Result of comparison operation */
  int rc = LSM_OK;
  int iMin;
  int iMax;
  LsmPgno iPtrOut = 0;

  /* If the current page contains an oversized entry, then there are no
  ** pointers to one or more of the subsequent pages in the sorted run.
  ** The following call ensures that the segment-ptr points to the correct 
  ** page in this case.  */
  rc = segmentPtrSearchOversized(pCsr, pPtr, iTopic, pKey, nKey);
  iPtrOut = pPtr->iPtr;

}

static int seekInBtree(
  MultiCursor *pCsr,              /* Multi-cursor object */
  Segment *pSeg,                  /* Seek within this segment */
  int iTopic,
  void *pKey, int nKey,           /* Key to seek to */
  LsmPgno *aPg,                   /* OUT: Page numbers */
  Page **ppPg                     /* OUT: Leaf (sorted-run) page reference */
){
  int i = 0;
  int rc;
  int iPg;
  Page *pPg = 0;
  LsmBlob blob = {0, 0, 0};

  iPg = (int)pSeg->iRoot;
  do {
    LsmPgno *piFirst = 0;
    if( aPg ){
      aPg[i++] = iPg;
      piFirst = &aPg[i];
    }

    rc = lsmFsDbPageGet(pCsr->pDb->pFS, pSeg, iPg, &pPg);
    assert( rc==LSM_OK || pPg==0 );

      iMin = 0;
      iMax = nRec-1;
      while( iMax>=iMin ){
        int iTry = (iMin+iMax)/2;
        void *pKeyT; int nKeyT;       /* Key for cell iTry */
        int iTopicT;                  /* Topic for key pKeyT/nKeyT */
        LsmPgno iPtr;                 /* Pointer associated with cell iTry */
        int res;                      /* (pKey - pKeyT) */

        rc = pageGetBtreeKey(
            pSeg, pPg, iTry, &iPtr, &iTopicT, &pKeyT, &nKeyT, &blob
        );
        if( rc!=LSM_OK ) break;
        if( piFirst && pKeyT==blob.pData ){

*/
static int seekInLevel(
  MultiCursor *pCsr,              /* Sorted cursor object to seek */
  SegmentPtr *aPtr,               /* Pointer to array of (nRhs+1) SPs */
  int eSeek,                      /* Search bias - see above */
  int iTopic,                     /* Key topic to search for */
  void *pKey, int nKey,           /* Key to search for */
  LsmPgno *piPgno,                /* IN/OUT: fraction cascade pointer (or 0) */
  int *pbStop                     /* OUT: See above */
){
  Level *pLvl = aPtr[0].pLevel;   /* Level to seek within */
  int rc = LSM_OK;                /* Return code */
  int iOut = 0;                   /* Pointer to return to caller */
  int res = -1;                   /* Result of xCmp(pKey, split) */
  int nRhs = pLvl->nRight;        /* Number of right-hand-side segments */

  void *pKey, int nKey, 
  int eSeek
){
  int eESeek = eSeek;             /* Effective eSeek parameter */
  int bStop = 0;                  /* Set to true to halt search operation */
  int rc = LSM_OK;                /* Return code */
  int iPtr = 0;                   /* Used to iterate through pCsr->aPtr[] */
  LsmPgno iPgno = 0;              /* FC pointer value */

  assert( pCsr->apTreeCsr[0]==0 || iTopic==0 );
  assert( pCsr->apTreeCsr[1]==0 || iTopic==0 );

  if( eESeek==LSM_SEEK_LEFAST ) eESeek = LSM_SEEK_LE;

  assert( eESeek==LSM_SEEK_EQ || eESeek==LSM_SEEK_LE || eESeek==LSM_SEEK_GE );

** differences are:
**
**   1. The record format is (usually, see below) as follows:
**
**         + Type byte (always SORTED_SEPARATOR or SORTED_SYSTEM_SEPARATOR),
**         + Absolute pointer value (varint),
**         + Number of bytes in key (varint),
**         + LsmBlob containing key data.
**
**   2. All pointer values are stored as absolute values (not offsets 
**      relative to the footer pointer value).
**
**   3. Each pointer that is part of a record points to a page that 
**      contains keys smaller than the records key (note: not "equal to or
**      smaller than - smaller than").

**
** See function seekInBtree() for the code that traverses b-tree pages.
*/

static int mergeWorkerBtreeWrite(
  MergeWorker *pMW,
  u8 eType,
  LsmPgno iPtr,
  LsmPgno iKeyPg,
  void *pKey,
  int nKey
){
  Hierarchy *p = &pMW->hier;
  lsm_db *pDb = pMW->pDb;         /* Database handle */
  int rc = LSM_OK;                /* Return Code */
  int iLevel;                     /* Level of b-tree hierachy to write to */

  return rc;
}

static int mergeWorkerBtreeIndirect(MergeWorker *pMW){
  int rc = LSM_OK;
  if( pMW->iIndirect ){
    LsmPgno iKeyPg = pMW->aSave[1].iPgno;
    rc = mergeWorkerBtreeWrite(pMW, 0, pMW->iIndirect, iKeyPg, 0, 0);
    pMW->iIndirect = 0;
  }
  return rc;
}

/*
** Append the database key (iTopic/pKey/nKey) to the b-tree under 
** construction. This key has not yet been written to a segment page.
** The pointer that will accompany the new key in the b-tree - that
** points to the completed segment page that contains keys smaller than
** (pKey/nKey) is currently stored in pMW->aSave[0].iPgno.
*/
static int mergeWorkerPushHierarchy(
  MergeWorker *pMW,               /* Merge worker object */
  int iTopic,                     /* Topic value for this key */
  void *pKey,                     /* Pointer to key buffer */
  int nKey                        /* Size of pKey buffer in bytes */
){
  int rc = LSM_OK;                /* Return Code */
  LsmPgno iPtr;                   /* Pointer value to accompany pKey/nKey */

  assert( pMW->aSave[0].bStore==0 );
  assert( pMW->aSave[1].bStore==0 );
  rc = mergeWorkerBtreeIndirect(pMW);

  /* Obtain the absolute pointer value to store along with the key in the
  ** page body. This pointer points to a page that contains keys that are

}

static int mergeWorkerFinishHierarchy(
  MergeWorker *pMW                /* Merge worker object */
){
  int i;                          /* Used to loop through apHier[] */
  int rc = LSM_OK;                /* Return code */
  LsmPgno iPtr;                   /* New right-hand-child pointer value */

  iPtr = pMW->aSave[0].iPgno;
  for(i=0; i<pMW->hier.nHier && rc==LSM_OK; i++){
    Page *pPg = pMW->hier.apHier[i];
    int nData;                    /* Size of aData[] in bytes */
    u8 *aData;                    /* Page data for pPg */

** zero records. The flags field is cleared. The page footer pointer field
** is set to iFPtr.
**
** If successful, LSM_OK is returned. Otherwise, an error code.
*/
static int mergeWorkerNextPage(
  MergeWorker *pMW,               /* Merge worker object to append page to */
  LsmPgno iFPtr                   /* Pointer value for footer of new page */
){
  int rc = LSM_OK;                /* Return code */
  Page *pNext = 0;                /* New page appended to run */
  lsm_db *pDb = pMW->pDb;         /* Database handle */

  rc = lsmFsSortedAppend(pDb->pFS, pDb->pWorker, pMW->pLevel, 0, &pNext);
  assert( rc || pMW->pLevel->lhs.iFirst>0 || pMW->pDb->compress.xCompress );

static int mergeWorkerStep(MergeWorker *pMW){
  lsm_db *pDb = pMW->pDb;       /* Database handle */
  MultiCursor *pCsr;            /* Cursor to read input data from */
  int rc = LSM_OK;              /* Return code */
  int eType;                    /* SORTED_SEPARATOR, WRITE or DELETE */
  void *pKey; int nKey;         /* Key */
  LsmPgno iPtr;
  int iVal;

  pCsr = pMW->pCsr;

  /* Pull the next record out of the source cursor. */
  lsmMCursorKey(pCsr, &pKey, &nKey);
  eType = pCsr->eType;

      multiCursorIgnoreDelete(pCsr);
    }
  }

  if( rc!=LSM_OK ){
    lsmMCursorClose(pCsr, 0);
  }else{
    LsmPgno iLeftPtr = 0;
    Merge merge;                  /* Merge object used to create new level */
    MergeWorker mergeworker;      /* MergeWorker object for the same purpose */

    memset(&merge, 0, sizeof(Merge));
    memset(&mergeworker, 0, sizeof(MergeWorker));

    pNew->pMerge = &merge;

  assert( pDb->pWorker );
  assert( pLevel->pMerge );
  assert( pLevel->nRight>0 );

  memset(pMW, 0, sizeof(MergeWorker));
  pMW->pDb = pDb;
  pMW->pLevel = pLevel;
  pMW->aGobble = lsmMallocZeroRc(pDb->pEnv, sizeof(LsmPgno)*pLevel->nRight,&rc);

  /* Create a multi-cursor to read the data to write to the new
  ** segment. The new segment contains:
  **
  **   1. Records from LHS of each of the nMerge levels being merged.
  **   2. Separators from either the last level being merged, or the
  **      separators attached to the LHS of the following level, or neither.

  lsm_db *pDb,                    /* Worker connection */
  MultiCursor *pCsr,              /* Multi-cursor being used for a merge */
  int iGobble                     /* pCsr->aPtr[] entry to operate on */
){
  int rc = LSM_OK;
  if( rtTopic(pCsr->eType)==0 ){
    Segment *pSeg = pCsr->aPtr[iGobble].pSeg;
    LsmPgno *aPg;
    int nPg;

    /* Seek from the root of the b-tree to the segment leaf that may contain
    ** a key equal to the one multi-cursor currently points to. Record the
    ** page number of each b-tree page and the leaf. The segment may be
    ** gobbled up to (but not including) the first of these page numbers.
    */
    assert( pSeg->iRoot>0 );
    aPg = lsmMallocZeroRc(pDb->pEnv, sizeof(LsmPgno)*32, &rc);
    if( rc==LSM_OK ){
      rc = seekInBtree(pCsr, pSeg, 
          rtTopic(pCsr->eType), pCsr->key.pData, pCsr->key.nData, aPg, 0
      ); 
    }

    if( rc==LSM_OK ){

    nRem -= nPg;
    if( nPg ) bDirty = 1;
  }

  /* If the in-memory part of the free-list is too large, write a new 
  ** top-level containing just the in-memory free-list entries to disk. */
  if( rc==LSM_OK && pDb->pWorker->freelist.nEntry > pDb->nMaxFreelist ){

    while( rc==LSM_OK && lsmDatabaseFull(pDb) ){
      int nPg = 0;
      rc = sortedWork(pDb, 16, nMerge, 1, &nPg);
      nRem -= nPg;
    }
    if( rc==LSM_OK ){
      rc = sortedNewFreelistOnly(pDb);
    }

    bDirty = 1;
  }

  if( rc==LSM_OK ){
    *pnWrite = (nMax - nRem);
    *pbCkpt = (bCkpt && nRem<=0);
    if( nMerge==1 && pDb->nAutockpt>0 && *pnWrite>0
     && pWorker->pLevel 

/*
** Return a string representation of the segment passed as the only argument.
** Space for the returned string is allocated using lsmMalloc(), and should
** be freed by the caller using lsmFree().
*/
static char *segToString(lsm_env *pEnv, Segment *pSeg, int nMin){
  int nSize = pSeg->nSize;
  LsmPgno iRoot = pSeg->iRoot;
  LsmPgno iFirst = pSeg->iFirst;
  LsmPgno iLast = pSeg->iLastPg;
  char *z;

  char *z1;
  char *z2;
  int nPad;

  z1 = lsmMallocPrintf(pEnv, "%d.%d", iFirst, iLast);

    aBuf[0] = '\0';
  }

  return i;
}

void sortedDumpPage(lsm_db *pDb, Segment *pRun, Page *pPg, int bVals){
  LsmBlob blob = {0, 0, 0};       /* LsmBlob used for keys */
  LsmString s;
  int i;

  int nRec;
  int iPtr;
  int flags;
  u8 *aData;

    aCell = pageGetCell(aData, nData, i);
    eType = *aCell++;
    assert( (flags & SEGMENT_BTREE_FLAG) || eType!=0 );
    aCell += lsmVarintGet32(aCell, &iPgPtr);

    if( eType==0 ){
      LsmPgno iRef;               /* Page number of referenced page */
      aCell += lsmVarintGet64(aCell, &iRef);
      lsmFsDbPageGet(pDb->pFS, pRun, iRef, &pRef);
      aKey = pageGetKey(pRun, pRef, 0, &iTopic, &nKey, &blob);
    }else{
      aCell += lsmVarintGet32(aCell, &nKey);
      if( rtIsWrite(eType) ) aCell += lsmVarintGet32(aCell, &nVal);
      sortedReadData(0, pPg, (aCell-aData), nKey+nVal, (void **)&aKey, &blob);

  int bIndirect,                  /* True to follow indirect refs */
  Page *pPg,
  int iCell,
  int *peType,
  int *piPgPtr,
  u8 **paKey, int *pnKey,
  u8 **paVal, int *pnVal,
  LsmBlob *pBlob
){
  u8 *aData; int nData;           /* Page data */
  u8 *aKey; int nKey = 0;         /* Key */
  u8 *aVal = 0; int nVal = 0;     /* Value */
  int eType;
  int iPgPtr;
  Page *pRef = 0;                 /* Pointer to page iRef */
  u8 *aCell;

  aData = fsPageData(pPg, &nData);

  aCell = pageGetCell(aData, nData, iCell);
  eType = *aCell++;
  aCell += lsmVarintGet32(aCell, &iPgPtr);

  if( eType==0 ){
    int dummy;
    LsmPgno iRef;                 /* Page number of referenced page */
    aCell += lsmVarintGet64(aCell, &iRef);
    if( bIndirect ){
      lsmFsDbPageGet(pDb->pFS, pSeg, iRef, &pRef);
      pageGetKeyCopy(pDb->pEnv, pSeg, pRef, 0, &dummy, pBlob);
      aKey = (u8 *)pBlob->pData;
      nKey = pBlob->nData;
      lsmFsPageRelease(pRef);

#define INFO_PAGE_DUMP_DATA     0x01
#define INFO_PAGE_DUMP_VALUES   0x02
#define INFO_PAGE_DUMP_HEX      0x04
#define INFO_PAGE_DUMP_INDIRECT 0x08

static int infoPageDump(
  lsm_db *pDb,                    /* Database handle */
  LsmPgno iPg,                    /* Page number of page to dump */
  int flags,
  char **pzOut                    /* OUT: lsmMalloc'd string */
){
  int rc = LSM_OK;                /* Return code */
  Page *pPg = 0;                  /* Handle for page iPg */
  int i, j;                       /* Loop counters */
  const int perLine = 16;         /* Bytes per line in the raw hex dump */

  ** to pass a NULL in place of the segment pointer as the second argument
  ** to lsmFsDbPageGet() here.  */
  if( rc==LSM_OK ){
    rc = lsmFsDbPageGet(pDb->pFS, 0, iPg, &pPg);
  }

  if( rc==LSM_OK ){
    LsmBlob blob = {0, 0, 0, 0};
    int nKeyWidth = 0;
    LsmString str;
    int nRec;
    int iPtr;
    int flags2;
    int iCell;
    u8 *aData; int nData;         /* Page data and size thereof */

    if( bHex ) nKeyWidth = nKeyWidth * 2;

    for(iCell=0; iCell<nRec; iCell++){
      u8 *aKey; int nKey = 0;       /* Key */
      u8 *aVal; int nVal = 0;       /* Value */
      int iPgPtr;
      int eType;
      LsmPgno iAbsPtr;
      char zFlags[8];

      infoCellDump(pDb, pSeg, bIndirect, pPg, iCell, &eType, &iPgPtr,
          &aKey, &nKey, &aVal, &nVal, &blob
      );
      iAbsPtr = iPgPtr + ((flags2 & SEGMENT_BTREE_FLAG) ? 0 : iPtr);

  }

  return rc;
}

int lsmInfoPageDump(
  lsm_db *pDb,                    /* Database handle */
  LsmPgno iPg,                    /* Page number of page to dump */
  int bHex,                       /* True to output key/value in hex form */
  char **pzOut                    /* OUT: lsmMalloc'd string */
){
  int flags = INFO_PAGE_DUMP_DATA | INFO_PAGE_DUMP_VALUES;
  if( bHex ) flags |= INFO_PAGE_DUMP_HEX;
  return infoPageDump(pDb, iPg, flags, pzOut);
}

  iHdr = SEGMENT_EOF(nOrig, nEntry);
  memmove(&aData[iHdr + (nData-nOrig)], &aData[iHdr], nOrig-iHdr);
}

#ifdef LSM_DEBUG_EXPENSIVE
static void assertRunInOrder(lsm_db *pDb, Segment *pSeg){
  Page *pPg = 0;
  LsmBlob blob1 = {0, 0, 0, 0};
  LsmBlob blob2 = {0, 0, 0, 0};

  lsmFsDbPageGet(pDb->pFS, pSeg, pSeg->iFirst, &pPg);
  while( pPg ){
    u8 *aData; int nData;
    Page *pNext;

    aData = lsmFsPageData(pPg, &nData);

  Segment *pOne,                  /* Segment containing pointers */
  Segment *pTwo,                  /* Segment containing pointer targets */
  int bRhs                        /* True if pTwo may have been Gobble()d */
){
  int rc = LSM_OK;                /* Error code */
  SegmentPtr ptr1;                /* Iterates through pOne */
  SegmentPtr ptr2;                /* Iterates through pTwo */
  LsmPgno iPrev;

  assert( pOne && pTwo );

  memset(&ptr1, 0, sizeof(ptr1));
  memset(&ptr2, 0, sizeof(ptr1));
  ptr1.pSeg = pOne;
  ptr2.pSeg = pTwo;

  }

  if( rc==LSM_OK && ptr1.nCell>0 ){
    rc = segmentPtrLoadCell(&ptr1, 0);
  }
      
  while( rc==LSM_OK && ptr2.pPg ){
    LsmPgno iThis;

    /* Advance to the next page of segment pTwo that contains at least
    ** one cell. Break out of the loop if the iterator reaches EOF.  */
    do{
      rc = segmentPtrNextPage(&ptr2, 1);
      assert( rc==LSM_OK );
    }while( rc==LSM_OK && ptr2.pPg && ptr2.nCell==0 );

*/
static int assertBtreeOk(
  lsm_db *pDb,
  Segment *pSeg
){
  int rc = LSM_OK;                /* Return code */
  if( pSeg->iRoot ){
    LsmBlob blob = {0, 0, 0};     /* Buffer used to cache overflow keys */
    FileSystem *pFS = pDb->pFS;   /* File system to read from */
    Page *pPg = 0;                /* Main run page */
    BtreeCursor *pCsr = 0;        /* Btree cursor */

    rc = btreeCursorNew(pDb, pSeg, &pCsr);
    if( rc==LSM_OK ){
      rc = btreeCursorFirst(pCsr);

#!/bin/sh
# restart with tclsh \
exec tclsh "$0" "$@"

set srcdir [file dirname [file dirname [info script]]]
set G(src) [string map [list %dir% $srcdir] {
  %dir%/lsm.h
  %dir%/lsmInt.h
  %dir%/lsm_vtab.c
  %dir%/lsm_ckpt.c
  %dir%/lsm_file.c
  %dir%/lsm_log.c
  %dir%/lsm_main.c
  %dir%/lsm_mem.c
  %dir%/lsm_mutex.c
  %dir%/lsm_shared.c
  %dir%/lsm_sorted.c
  %dir%/lsm_str.c
  %dir%/lsm_tree.c
  %dir%/lsm_unix.c
  %dir%/lsm_varint.c
  %dir%/lsm_win32.c
}]

set G(hdr) {

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_LSM1) 

#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
# define NDEBUG 1
#endif
#if defined(NDEBUG) && defined(SQLITE_DEBUG)
# undef NDEBUG
#endif

}

set G(footer) {
    
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_LSM1) */
}

#-------------------------------------------------------------------------
# Read and return the entire contents of text file $zFile from disk.
#
proc readfile {zFile} {
  set fd [open $zFile]
  set data [read $fd]
  close $fd
  return $data
}

proc lsm1c_init {zOut} {
  global G
  set G(fd) stdout
  set G(fd) [open $zOut w]

  puts -nonewline $G(fd) $G(hdr)
}

proc lsm1c_printfile {zIn} {
  global G
  set data [readfile $zIn]
  set zTail [file tail $zIn]
  puts $G(fd) "#line 1 \"$zTail\""

  foreach line [split $data "\n"] {
    if {[regexp {^# *include.*lsm} $line]} {
      set line "/* $line */"
    } elseif { [regexp {^(const )?[a-zA-Z][a-zA-Z0-9]* [*]?lsm[^_]} $line] } {
      set line "static $line"
    }
    puts $G(fd) $line
  }
}

proc lsm1c_close {} {
  global G
  puts -nonewline $G(fd) $G(footer)
  if {$G(fd)!="stdout"} {
    close $G(fd)
  }
}


lsm1c_init lsm1.c
foreach f $G(src) { lsm1c_printfile $f }
lsm1c_close

as follows:

  *  **carray.c** —  This module implements the
     [carray](https://www.sqlite.org/carray.html) table-valued function.
     It is a good example of how to go about implementing a custom
     [table-valued function](https://www.sqlite.org/vtab.html#tabfunc2).

  *  **csv.c** —  A [virtual table](https://sqlite.org/vtab.html)
     for reading 
     [Comma-Separated-Value (CSV) files](https://en.wikipedia.org/wiki/Comma-separated_values).

  *  **dbdump.c** —  This is not actually a loadable extension, but
     rather a library that implements an approximate equivalent to the
     ".dump" command of the
     [command-line shell](https://www.sqlite.org/cli.html).

  *  **json1.c** —  Various SQL functions and table-valued functions
     for processing JSON.  This extension is already built into the
     [SQLite amalgamation](https://sqlite.org/amalgamation.html).  See
     <https://sqlite.org/json1.html> for additional information.

  *  **memvfs.c** &mdash;  This file implements a custom
     [VFS](https://www.sqlite.org/vfs.html) that stores an entire database
     file in a single block of RAM.  It serves as a good example of how
     to implement a simple custom VFS.

  *  **rot13.c** &mdash;  This file implements the very simple rot13()
     substitution function.  This file makes a good template for implementing
     new custom SQL functions for SQLite.

  *  **series.c** &mdash;  This is an implementation of the
     "generate_series" [virtual table](https://www.sqlite.org/vtab.html).
     It can make a good template for new custom virtual table implementations.

  *  **shathree.c** &mdash;  An implementation of the sha3() and
     sha3_query() SQL functions.  The file is named "shathree.c" instead
     of "sha3.c" because the default entry point names in SQLite are based
     on the source filename with digits removed, so if we used the name
     "sha3.c" then the entry point would conflict with the prior "sha1.c"
     extension.

  *  **unionvtab.c** &mdash; Implementation of the unionvtab and
     [swarmvtab](https://sqlite.org/swarmvtab.html) virtual tables.
     These virtual tables allow a single
     large table to be spread out across multiple database files.  In the
     case of swarmvtab, the individual database files can be attached on
     demand.

  *  **zipfile.c** &mdash;  A [virtual table](https://sqlite.org/vtab.html)
     that can read and write a 
     [ZIP archive](https://en.wikipedia.org/wiki/Zip_%28file_format%29).

/*
** 2017-10-20
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file implements a VFS shim that allows an SQLite database to be
** appended onto the end of some other file, such as an executable.
**
** A special record must appear at the end of the file that identifies the
** file as an appended database and provides an offset to page 1.  For
** best performance page 1 should be located at a disk page boundary, though
** that is not required.
**
** When opening a database using this VFS, the connection might treat
** the file as an ordinary SQLite database, or it might treat is as a
** database appended onto some other file.  Here are the rules:
**
**  (1)  When opening a new empty file, that file is treated as an ordinary
**       database.
**
**  (2)  When opening a file that begins with the standard SQLite prefix
**       string "SQLite format 3", that file is treated as an ordinary
**       database.
**
**  (3)  When opening a file that ends with the appendvfs trailer string
**       "Start-Of-SQLite3-NNNNNNNN" that file is treated as an appended
**       database.
**
**  (4)  If none of the above apply and the SQLITE_OPEN_CREATE flag is
**       set, then a new database is appended to the already existing file.
**
**  (5)  Otherwise, SQLITE_CANTOPEN is returned.
**
** To avoid unnecessary complications with the PENDING_BYTE, the size of
** the file containing the database is limited to 1GB.  This VFS will refuse
** to read or write past the 1GB mark.  This restriction might be lifted in
** future versions.  For now, if you need a large database, then keep the
** database in a separate file.
**
** If the file being opened is not an appended database, then this shim is
** a pass-through into the default underlying VFS.
**/
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <string.h>
#include <assert.h>

/* The append mark at the end of the database is:
**
**     Start-Of-SQLite3-NNNNNNNN
**     123456789 123456789 12345
**
** The NNNNNNNN represents a 64-bit big-endian unsigned integer which is
** the offset to page 1.
*/
#define APND_MARK_PREFIX     "Start-Of-SQLite3-"
#define APND_MARK_PREFIX_SZ  17
#define APND_MARK_SIZE       25

/*
** Maximum size of the combined prefix + database + append-mark.  This
** must be less than 0x40000000 to avoid locking issues on Windows.
*/
#define APND_MAX_SIZE  (65536*15259)

/*
** Forward declaration of objects used by this utility
*/
typedef struct sqlite3_vfs ApndVfs;
typedef struct ApndFile ApndFile;

/* Access to a lower-level VFS that (might) implement dynamic loading,
** access to randomness, etc.
*/
#define ORIGVFS(p)  ((sqlite3_vfs*)((p)->pAppData))
#define ORIGFILE(p) ((sqlite3_file*)(((ApndFile*)(p))+1))

/* An open file */
struct ApndFile {
  sqlite3_file base;              /* IO methods */
  sqlite3_int64 iPgOne;           /* File offset to page 1 */
  sqlite3_int64 iMark;            /* Start of the append-mark */
};

/*
** Methods for ApndFile
*/
static int apndClose(sqlite3_file*);
static int apndRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int apndWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst);
static int apndTruncate(sqlite3_file*, sqlite3_int64 size);
static int apndSync(sqlite3_file*, int flags);
static int apndFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int apndLock(sqlite3_file*, int);
static int apndUnlock(sqlite3_file*, int);
static int apndCheckReservedLock(sqlite3_file*, int *pResOut);
static int apndFileControl(sqlite3_file*, int op, void *pArg);
static int apndSectorSize(sqlite3_file*);
static int apndDeviceCharacteristics(sqlite3_file*);
static int apndShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**);
static int apndShmLock(sqlite3_file*, int offset, int n, int flags);
static void apndShmBarrier(sqlite3_file*);
static int apndShmUnmap(sqlite3_file*, int deleteFlag);
static int apndFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
static int apndUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);

/*
** Methods for ApndVfs
*/
static int apndOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *);
static int apndDelete(sqlite3_vfs*, const char *zName, int syncDir);
static int apndAccess(sqlite3_vfs*, const char *zName, int flags, int *);
static int apndFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
static void *apndDlOpen(sqlite3_vfs*, const char *zFilename);
static void apndDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
static void (*apndDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void);
static void apndDlClose(sqlite3_vfs*, void*);
static int apndRandomness(sqlite3_vfs*, int nByte, char *zOut);
static int apndSleep(sqlite3_vfs*, int microseconds);
static int apndCurrentTime(sqlite3_vfs*, double*);
static int apndGetLastError(sqlite3_vfs*, int, char *);
static int apndCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*);
static int apndSetSystemCall(sqlite3_vfs*, const char*,sqlite3_syscall_ptr);
static sqlite3_syscall_ptr apndGetSystemCall(sqlite3_vfs*, const char *z);
static const char *apndNextSystemCall(sqlite3_vfs*, const char *zName);

static sqlite3_vfs apnd_vfs = {
  3,                            /* iVersion (set when registered) */
  0,                            /* szOsFile (set when registered) */
  1024,                         /* mxPathname */
  0,                            /* pNext */
  "apndvfs",                    /* zName */
  0,                            /* pAppData (set when registered) */ 
  apndOpen,                     /* xOpen */
  apndDelete,                   /* xDelete */
  apndAccess,                   /* xAccess */
  apndFullPathname,             /* xFullPathname */
  apndDlOpen,                   /* xDlOpen */
  apndDlError,                  /* xDlError */
  apndDlSym,                    /* xDlSym */
  apndDlClose,                  /* xDlClose */
  apndRandomness,               /* xRandomness */
  apndSleep,                    /* xSleep */
  apndCurrentTime,              /* xCurrentTime */
  apndGetLastError,             /* xGetLastError */
  apndCurrentTimeInt64,         /* xCurrentTimeInt64 */
  apndSetSystemCall,            /* xSetSystemCall */
  apndGetSystemCall,            /* xGetSystemCall */
  apndNextSystemCall            /* xNextSystemCall */
};

static const sqlite3_io_methods apnd_io_methods = {
  3,                              /* iVersion */
  apndClose,                      /* xClose */
  apndRead,                       /* xRead */
  apndWrite,                      /* xWrite */
  apndTruncate,                   /* xTruncate */
  apndSync,                       /* xSync */
  apndFileSize,                   /* xFileSize */
  apndLock,                       /* xLock */
  apndUnlock,                     /* xUnlock */
  apndCheckReservedLock,          /* xCheckReservedLock */
  apndFileControl,                /* xFileControl */
  apndSectorSize,                 /* xSectorSize */
  apndDeviceCharacteristics,      /* xDeviceCharacteristics */
  apndShmMap,                     /* xShmMap */
  apndShmLock,                    /* xShmLock */
  apndShmBarrier,                 /* xShmBarrier */
  apndShmUnmap,                   /* xShmUnmap */
  apndFetch,                      /* xFetch */
  apndUnfetch                     /* xUnfetch */
};



/*
** Close an apnd-file.
*/
static int apndClose(sqlite3_file *pFile){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xClose(pFile);
}

/*
** Read data from an apnd-file.
*/
static int apndRead(
  sqlite3_file *pFile, 
  void *zBuf, 
  int iAmt, 
  sqlite_int64 iOfst
){
  ApndFile *p = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xRead(pFile, zBuf, iAmt, iOfst+p->iPgOne);
}

/*
** Add the append-mark onto the end of the file.
*/
static int apndWriteMark(ApndFile *p, sqlite3_file *pFile){
  int i;
  unsigned char a[APND_MARK_SIZE];
  memcpy(a, APND_MARK_PREFIX, APND_MARK_PREFIX_SZ);
  for(i=0; i<8; i++){
    a[APND_MARK_PREFIX_SZ+i] = (p->iPgOne >> (56 - i*8)) & 0xff;
  }
  return pFile->pMethods->xWrite(pFile, a, APND_MARK_SIZE, p->iMark);
}

/*
** Write data to an apnd-file.
*/
static int apndWrite(
  sqlite3_file *pFile,
  const void *zBuf,
  int iAmt,
  sqlite_int64 iOfst
){
  int rc;
  ApndFile *p = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  if( iOfst+iAmt>=APND_MAX_SIZE ) return SQLITE_FULL;
  rc = pFile->pMethods->xWrite(pFile, zBuf, iAmt, iOfst+p->iPgOne);
  if( rc==SQLITE_OK &&  iOfst + iAmt + p->iPgOne > p->iMark ){
    sqlite3_int64 sz = 0;
    rc = pFile->pMethods->xFileSize(pFile, &sz);
    if( rc==SQLITE_OK ){
      p->iMark = sz - APND_MARK_SIZE;
      if( iOfst + iAmt + p->iPgOne > p->iMark ){
        p->iMark = p->iPgOne + iOfst + iAmt;
        rc = apndWriteMark(p, pFile);
      }
    }
  }
  return rc;
}

/*
** Truncate an apnd-file.
*/
static int apndTruncate(sqlite3_file *pFile, sqlite_int64 size){
  int rc;
  ApndFile *p = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  rc = pFile->pMethods->xTruncate(pFile, size+p->iPgOne+APND_MARK_SIZE);
  if( rc==SQLITE_OK ){
    p->iMark = p->iPgOne+size;
    rc = apndWriteMark(p, pFile);
  }
  return rc;
}

/*
** Sync an apnd-file.
*/
static int apndSync(sqlite3_file *pFile, int flags){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xSync(pFile, flags);
}

/*
** Return the current file-size of an apnd-file.
*/
static int apndFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
  ApndFile *p = (ApndFile *)pFile;
  int rc;
  pFile = ORIGFILE(p);
  rc = pFile->pMethods->xFileSize(pFile, pSize);
  if( rc==SQLITE_OK && p->iPgOne ){
    *pSize -= p->iPgOne + APND_MARK_SIZE;
  }
  return rc;
}

/*
** Lock an apnd-file.
*/
static int apndLock(sqlite3_file *pFile, int eLock){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xLock(pFile, eLock);
}

/*
** Unlock an apnd-file.
*/
static int apndUnlock(sqlite3_file *pFile, int eLock){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xUnlock(pFile, eLock);
}

/*
** Check if another file-handle holds a RESERVED lock on an apnd-file.
*/
static int apndCheckReservedLock(sqlite3_file *pFile, int *pResOut){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xCheckReservedLock(pFile, pResOut);
}

/*
** File control method. For custom operations on an apnd-file.
*/
static int apndFileControl(sqlite3_file *pFile, int op, void *pArg){
  ApndFile *p = (ApndFile *)pFile;
  int rc;
  pFile = ORIGFILE(pFile);
  rc = pFile->pMethods->xFileControl(pFile, op, pArg);
  if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){
    *(char**)pArg = sqlite3_mprintf("apnd(%lld)/%z", p->iPgOne, *(char**)pArg);
  }
  return rc;
}

/*
** Return the sector-size in bytes for an apnd-file.
*/
static int apndSectorSize(sqlite3_file *pFile){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xSectorSize(pFile);
}

/*
** Return the device characteristic flags supported by an apnd-file.
*/
static int apndDeviceCharacteristics(sqlite3_file *pFile){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xDeviceCharacteristics(pFile);
}

/* Create a shared memory file mapping */
static int apndShmMap(
  sqlite3_file *pFile,
  int iPg,
  int pgsz,
  int bExtend,
  void volatile **pp
){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xShmMap(pFile,iPg,pgsz,bExtend,pp);
}

/* Perform locking on a shared-memory segment */
static int apndShmLock(sqlite3_file *pFile, int offset, int n, int flags){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xShmLock(pFile,offset,n,flags);
}

/* Memory barrier operation on shared memory */
static void apndShmBarrier(sqlite3_file *pFile){
  pFile = ORIGFILE(pFile);
  pFile->pMethods->xShmBarrier(pFile);
}

/* Unmap a shared memory segment */
static int apndShmUnmap(sqlite3_file *pFile, int deleteFlag){
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xShmUnmap(pFile,deleteFlag);
}

/* Fetch a page of a memory-mapped file */
static int apndFetch(
  sqlite3_file *pFile,
  sqlite3_int64 iOfst,
  int iAmt,
  void **pp
){
  ApndFile *p = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xFetch(pFile, iOfst+p->iPgOne, iAmt, pp);
}

/* Release a memory-mapped page */
static int apndUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){
  ApndFile *p = (ApndFile *)pFile;
  pFile = ORIGFILE(pFile);
  return pFile->pMethods->xUnfetch(pFile, iOfst+p->iPgOne, pPage);
}

/*
** Check to see if the file is an ordinary SQLite database file.
*/
static int apndIsOrdinaryDatabaseFile(sqlite3_int64 sz, sqlite3_file *pFile){
  int rc;
  char zHdr[16];
  static const char aSqliteHdr[] = "SQLite format 3";
  if( sz<512 ) return 0;
  rc = pFile->pMethods->xRead(pFile, zHdr, sizeof(zHdr), 0);
  if( rc ) return 0;
  return memcmp(zHdr, aSqliteHdr, sizeof(zHdr))==0;
}

/*
** Try to read the append-mark off the end of a file.  Return the
** start of the appended database if the append-mark is present.  If
** there is no append-mark, return -1;
*/
static sqlite3_int64 apndReadMark(sqlite3_int64 sz, sqlite3_file *pFile){
  int rc, i;
  sqlite3_int64 iMark;
  unsigned char a[APND_MARK_SIZE];

  if( sz<=APND_MARK_SIZE ) return -1;
  rc = pFile->pMethods->xRead(pFile, a, APND_MARK_SIZE, sz-APND_MARK_SIZE);
  if( rc ) return -1;
  if( memcmp(a, APND_MARK_PREFIX, APND_MARK_PREFIX_SZ)!=0 ) return -1;
  iMark = ((sqlite3_int64)(a[APND_MARK_PREFIX_SZ]&0x7f))<<56;
  for(i=1; i<8; i++){    
    iMark += (sqlite3_int64)a[APND_MARK_PREFIX_SZ+i]<<(56-8*i);
  }
  return iMark;
}

/*
** Open an apnd file handle.
*/
static int apndOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  ApndFile *p;
  sqlite3_file *pSubFile;
  sqlite3_vfs *pSubVfs;
  int rc;
  sqlite3_int64 sz;
  pSubVfs = ORIGVFS(pVfs);
  if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){
    return pSubVfs->xOpen(pSubVfs, zName, pFile, flags, pOutFlags);
  }
  p = (ApndFile*)pFile;
  memset(p, 0, sizeof(*p));
  pSubFile = ORIGFILE(pFile);
  p->base.pMethods = &apnd_io_methods;
  rc = pSubVfs->xOpen(pSubVfs, zName, pSubFile, flags, pOutFlags);
  if( rc ) goto apnd_open_done;
  rc = pSubFile->pMethods->xFileSize(pSubFile, &sz);
  if( rc ){
    pSubFile->pMethods->xClose(pSubFile);
    goto apnd_open_done;
  }
  if( apndIsOrdinaryDatabaseFile(sz, pSubFile) ){
    memmove(pFile, pSubFile, pSubVfs->szOsFile);
    return SQLITE_OK;
  }
  p->iMark = 0;
  p->iPgOne = apndReadMark(sz, pFile);
  if( p->iPgOne>0 ){
    return SQLITE_OK;
  }
  if( (flags & SQLITE_OPEN_CREATE)==0 ){
    pSubFile->pMethods->xClose(pSubFile);
    rc = SQLITE_CANTOPEN;
  }
  p->iPgOne = (sz+0xfff) & ~(sqlite3_int64)0xfff;
apnd_open_done:
  if( rc ) pFile->pMethods = 0;
  return rc;
}

/*
** All other VFS methods are pass-thrus.
*/
static int apndDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  return ORIGVFS(pVfs)->xDelete(ORIGVFS(pVfs), zPath, dirSync);
}
static int apndAccess(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int flags, 
  int *pResOut
){
  return ORIGVFS(pVfs)->xAccess(ORIGVFS(pVfs), zPath, flags, pResOut);
}
static int apndFullPathname(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  int nOut, 
  char *zOut
){
  return ORIGVFS(pVfs)->xFullPathname(ORIGVFS(pVfs),zPath,nOut,zOut);
}
static void *apndDlOpen(sqlite3_vfs *pVfs, const char *zPath){
  return ORIGVFS(pVfs)->xDlOpen(ORIGVFS(pVfs), zPath);
}
static void apndDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
  ORIGVFS(pVfs)->xDlError(ORIGVFS(pVfs), nByte, zErrMsg);
}
static void (*apndDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){
  return ORIGVFS(pVfs)->xDlSym(ORIGVFS(pVfs), p, zSym);
}
static void apndDlClose(sqlite3_vfs *pVfs, void *pHandle){
  ORIGVFS(pVfs)->xDlClose(ORIGVFS(pVfs), pHandle);
}
static int apndRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){
  return ORIGVFS(pVfs)->xRandomness(ORIGVFS(pVfs), nByte, zBufOut);
}
static int apndSleep(sqlite3_vfs *pVfs, int nMicro){
  return ORIGVFS(pVfs)->xSleep(ORIGVFS(pVfs), nMicro);
}
static int apndCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
  return ORIGVFS(pVfs)->xCurrentTime(ORIGVFS(pVfs), pTimeOut);
}
static int apndGetLastError(sqlite3_vfs *pVfs, int a, char *b){
  return ORIGVFS(pVfs)->xGetLastError(ORIGVFS(pVfs), a, b);
}
static int apndCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){
  return ORIGVFS(pVfs)->xCurrentTimeInt64(ORIGVFS(pVfs), p);
}
static int apndSetSystemCall(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_syscall_ptr pCall
){
  return ORIGVFS(pVfs)->xSetSystemCall(ORIGVFS(pVfs),zName,pCall);
}
static sqlite3_syscall_ptr apndGetSystemCall(
  sqlite3_vfs *pVfs,
  const char *zName
){
  return ORIGVFS(pVfs)->xGetSystemCall(ORIGVFS(pVfs),zName);
}
static const char *apndNextSystemCall(sqlite3_vfs *pVfs, const char *zName){
  return ORIGVFS(pVfs)->xNextSystemCall(ORIGVFS(pVfs), zName);
}

  
#ifdef _WIN32
__declspec(dllexport)
#endif
/* 
** This routine is called when the extension is loaded.
** Register the new VFS.
*/
int sqlite3_appendvfs_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  int rc = SQLITE_OK;
  sqlite3_vfs *pOrig;
  SQLITE_EXTENSION_INIT2(pApi);
  pOrig = sqlite3_vfs_find(0);
  apnd_vfs.iVersion = pOrig->iVersion;
  apnd_vfs.pAppData = pOrig;
  apnd_vfs.szOsFile = pOrig->szOsFile + sizeof(ApndFile);
  rc = sqlite3_vfs_register(&apnd_vfs, 0);
#ifdef APPENDVFS_TEST
  if( rc==SQLITE_OK ){
    rc = sqlite3_auto_extension((void(*)(void))apndvfsRegister);
  }
#endif
  if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY;
  return rc;
}

**
** The output is a BLOB that begins with a variable-length integer that
** is the input size in bytes (the size of X before compression).  The
** variable-length integer is implemented as 1 to 5 bytes.  There are
** seven bits per integer stored in the lower seven bits of each byte.
** More significant bits occur first.  The most significant bit (0x80)
** is a flag to indicate the end of the integer.
**
** This function, SQLAR, and ZIP all use the same "deflate" compression
** algorithm, but each is subtly different:
**
**   *  ZIP uses raw deflate.
**
**   *  SQLAR uses the "zlib format" which is raw deflate with a two-byte
**      algorithm-identification header and a four-byte checksum at the end.
**
**   *  This utility uses the "zlib format" like SQLAR, but adds the variable-
**      length integer uncompressed size value at the beginning.
**
** This function might be extended in the future to support compression
** formats other than deflate, by providing a different algorithm-id
** mark following the variable-length integer size parameter.
*/
static void compressFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const unsigned char *pIn;

/*
** 2014-06-13
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
******************************************************************************
**
** This SQLite extension implements SQL functions readfile() and
** writefile(), and eponymous virtual type "fsdir".
**
** WRITEFILE(FILE, DATA [, MODE [, MTIME]]):
**
**   If neither of the optional arguments is present, then this UDF
**   function writes blob DATA to file FILE. If successful, the number
**   of bytes written is returned. If an error occurs, NULL is returned.
**
**   If the first option argument - MODE - is present, then it must
**   be passed an integer value that corresponds to a POSIX mode
**   value (file type + permissions, as returned in the stat.st_mode
**   field by the stat() system call). Three types of files may
**   be written/created:
**
**     regular files:  (mode & 0170000)==0100000
**     symbolic links: (mode & 0170000)==0120000
**     directories:    (mode & 0170000)==0040000
**
**   For a directory, the DATA is ignored. For a symbolic link, it is
**   interpreted as text and used as the target of the link. For a
**   regular file, it is interpreted as a blob and written into the
**   named file. Regardless of the type of file, its permissions are
**   set to (mode & 0777) before returning.
**
**   If the optional MTIME argument is present, then it is interpreted
**   as an integer - the number of seconds since the unix epoch. The
**   modification-time of the target file is set to this value before
**   returning.
**
**   If three or more arguments are passed to this function and an
**   error is encountered, an exception is raised.
**
** READFILE(FILE):
**
**   Read and return the contents of file FILE (type blob) from disk.
**
** FSDIR:
**
**   Used as follows:
**
**     SELECT * FROM fsdir($path [, $dir]);
**
**   Parameter $path is an absolute or relative pathname. If the file that it
**   refers to does not exist, it is an error. If the path refers to a regular
**   file or symbolic link, it returns a single row. Or, if the path refers
**   to a directory, it returns one row for the directory, and one row for each
**   file within the hierarchy rooted at $path.
**
**   Each row has the following columns:
**
**     name:  Path to file or directory (text value).
**     mode:  Value of stat.st_mode for directory entry (an integer).
**     mtime: Value of stat.st_mtime for directory entry (an integer).
**     data:  For a regular file, a blob containing the file data. For a
**            symlink, a text value containing the text of the link. For a
**            directory, NULL.
**
**   If a non-NULL value is specified for the optional $dir parameter and
**   $path is a relative path, then $path is interpreted relative to $dir. 
**   And the paths returned in the "name" column of the table are also 
**   relative to directory $dir.
*/
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#include <stdio.h>
#include <string.h>
#include <assert.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#if !defined(_WIN32) && !defined(WIN32)
#  include <unistd.h>
#  include <dirent.h>
#  include <utime.h>
#  include <sys/time.h>
#else
#  include "windows.h"
#  include <io.h>
#  include <direct.h>
#  include "test_windirent.h"
#  define dirent DIRENT
#  ifndef stat
#    define stat _stat
#  endif
#  define mkdir(path,mode) _mkdir(path)
#  define lstat(path,buf) stat(path,buf)
#endif
#include <time.h>
#include <errno.h>


#define FSDIR_SCHEMA "(name,mode,mtime,data,path HIDDEN,dir HIDDEN)"

/*
** Set the result stored by context ctx to a blob containing the 
** contents of file zName.
*/
static void readFileContents(sqlite3_context *ctx, const char *zName){
  FILE *in;
  long nIn;
  void *pBuf;

  in = fopen(zName, "rb");
  if( in==0 ) return;
  fseek(in, 0, SEEK_END);
  nIn = ftell(in);
  rewind(in);
  pBuf = sqlite3_malloc( nIn );
  if( pBuf && 1==fread(pBuf, nIn, 1, in) ){
    sqlite3_result_blob(ctx, pBuf, nIn, sqlite3_free);
  }else{
    sqlite3_free(pBuf);
  }
  fclose(in);
}

/*
** Implementation of the "readfile(X)" SQL function.  The entire content
** of the file named X is read and returned as a BLOB.  NULL is returned
** if the file does not exist or is unreadable.
*/
static void readfileFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  const char *zName;




  (void)(argc);  /* Unused parameter */
  zName = (const char*)sqlite3_value_text(argv[0]);
  if( zName==0 ) return;
  readFileContents(context, zName);
}

/*
** Set the error message contained in context ctx to the results of
** vprintf(zFmt, ...).
*/
static void ctxErrorMsg(sqlite3_context *ctx, const char *zFmt, ...){
  char *zMsg = 0;
  va_list ap;
  va_start(ap, zFmt);
  zMsg = sqlite3_vmprintf(zFmt, ap);
  sqlite3_result_error(ctx, zMsg, -1);
  sqlite3_free(zMsg);
  va_end(ap);
}

/*
** Argument zFile is the name of a file that will be created and/or written
** by SQL function writefile(). This function ensures that the directory
** zFile will be written to exists, creating it if required. The permissions
** for any path components created by this function are set to (mode&0777).
**
** If an OOM condition is encountered, SQLITE_NOMEM is returned. Otherwise,
** SQLITE_OK is returned if the directory is successfully created, or
** SQLITE_ERROR otherwise.
*/
static int makeDirectory(
  const char *zFile,
  mode_t mode
){
  char *zCopy = sqlite3_mprintf("%s", zFile);
  int rc = SQLITE_OK;


  if( zCopy==0 ){
    rc = SQLITE_NOMEM;
  }else{
    int nCopy = (int)strlen(zCopy);
    int i = 1;

    while( rc==SQLITE_OK ){
      struct stat sStat;
      int rc2;

      for(; zCopy[i]!='/' && i<nCopy; i++);
      if( i==nCopy ) break;
      zCopy[i] = '\0';

      rc2 = stat(zCopy, &sStat);
      if( rc2!=0 ){
        if( mkdir(zCopy, mode & 0777) ) rc = SQLITE_ERROR;
      }else{
        if( !S_ISDIR(sStat.st_mode) ) rc = SQLITE_ERROR;
      }
      zCopy[i] = '/';
      i++;
    }

    sqlite3_free(zCopy);
  }

  return rc;
}

/*
** This function does the work for the writefile() UDF. Refer to 
** header comments at the top of this file for details.
*/
static int writeFile(
  sqlite3_context *pCtx,          /* Context to return bytes written in */
  const char *zFile,              /* File to write */
  sqlite3_value *pData,           /* Data to write */
  mode_t mode,                    /* MODE parameter passed to writefile() */
  sqlite3_int64 mtime             /* MTIME parameter (or -1 to not set time) */
){
#if !defined(_WIN32) && !defined(WIN32)
  if( S_ISLNK(mode) ){
    const char *zTo = (const char*)sqlite3_value_text(pData);
    if( symlink(zTo, zFile)<0 ) return 1;
  }else
#endif
  {
    if( S_ISDIR(mode) ){
      if( mkdir(zFile, mode) ){
        /* The mkdir() call to create the directory failed. This might not
        ** be an error though - if there is already a directory at the same
        ** path and either the permissions already match or can be changed
        ** to do so using chmod(), it is not an error.  */
        struct stat sStat;
        if( errno!=EEXIST
         || 0!=stat(zFile, &sStat)
         || !S_ISDIR(sStat.st_mode)
         || ((sStat.st_mode&0777)!=(mode&0777) && 0!=chmod(zFile, mode&0777))
        ){
          return 1;
        }
      }
    }else{
      sqlite3_int64 nWrite = 0;
      const char *z;
      int rc = 0;
      FILE *out = fopen(zFile, "wb");
      if( out==0 ) return 1;
      z = (const char*)sqlite3_value_blob(pData);
      if( z ){
        sqlite3_int64 n = fwrite(z, 1, sqlite3_value_bytes(pData), out);
        nWrite = sqlite3_value_bytes(pData);
        if( nWrite!=n ){
          rc = 1;
        }
      }
      fclose(out);
      if( rc==0 && mode && chmod(zFile, mode & 0777) ){
        rc = 1;
      }
      if( rc ) return 2;
      sqlite3_result_int64(pCtx, nWrite);
    }
  }

  if( mtime>=0 ){
#if defined(_WIN32)
    /* Windows */
    FILETIME lastAccess;
    FILETIME lastWrite;
    SYSTEMTIME currentTime;
    LONGLONG intervals;
    HANDLE hFile;
    GetSystemTime(&currentTime);
    SystemTimeToFileTime(&currentTime, &lastAccess);
    intervals = Int32x32To64(mtime, 10000000) + 116444736000000000;
    lastWrite.dwLowDateTime = (DWORD)intervals;
    lastWrite.dwHighDateTime = intervals >> 32;
    hFile = CreateFile(
      zFile, FILE_WRITE_ATTRIBUTES, 0, NULL, OPEN_EXISTING,
      FILE_FLAG_BACKUP_SEMANTICS, NULL
    );
    if( hFile!=INVALID_HANDLE_VALUE ){
      BOOL bResult = SetFileTime(hFile, NULL, &lastAccess, &lastWrite);
      CloseHandle(hFile);
      return !bResult;
    }else{
      return 1;
    }
#elif defined(AT_FDCWD) && 0 /* utimensat() is not univerally available */
    /* Recent unix */
    struct timespec times[2];
    times[0].tv_nsec = times[1].tv_nsec = 0;
    times[0].tv_sec = time(0);
    times[1].tv_sec = mtime;
    if( utimensat(AT_FDCWD, zFile, times, AT_SYMLINK_NOFOLLOW) ){
      return 1;
    }
#else
    /* Legacy unix */
    struct timeval times[2];
    times[0].tv_usec = times[1].tv_usec = 0;
    times[0].tv_sec = time(0);
    times[1].tv_sec = mtime;
    if( utimes(zFile, times) ){
      return 1;
    }
#endif
  }

  return 0;
}

/*
** Implementation of the "writefile(W,X[,Y[,Z]]])" SQL function.  
** Refer to header comments at the top of this file for details.


*/
static void writefileFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){

  const char *zFile;
  mode_t mode = 0;
  int res;
  sqlite3_int64 mtime = -1;

  if( argc<2 || argc>4 ){
    sqlite3_result_error(context, 
        "wrong number of arguments to function writefile()", -1
    );
    return;
  }

  zFile = (const char*)sqlite3_value_text(argv[0]);
  if( zFile==0 ) return;
  if( argc>=3 ){
    mode = (mode_t)sqlite3_value_int(argv[2]);
  }
  if( argc==4 ){
    mtime = sqlite3_value_int64(argv[3]);
  }

  res = writeFile(context, zFile, argv[1], mode, mtime);
  if( res==1 && errno==ENOENT ){
    if( makeDirectory(zFile, mode)==SQLITE_OK ){
      res = writeFile(context, zFile, argv[1], mode, mtime);
    }
  }

  if( argc>2 && res!=0 ){
    if( S_ISLNK(mode) ){
      ctxErrorMsg(context, "failed to create symlink: %s", zFile);
    }else if( S_ISDIR(mode) ){
      ctxErrorMsg(context, "failed to create directory: %s", zFile);
    }else{
      ctxErrorMsg(context, "failed to write file: %s", zFile);
    }
  }
}

/*
** SQL function:   lsmode(MODE)
**
** Given a numberic st_mode from stat(), convert it into a human-readable
** text string in the style of "ls -l".
*/
static void lsModeFunc(
  sqlite3_context *context,
  int argc,
  sqlite3_value **argv
){
  int i;
  int iMode = sqlite3_value_int(argv[0]);
  char z[16];
  if( S_ISLNK(iMode) ){
    z[0] = 'l';
  }else if( S_ISREG(iMode) ){
    z[0] = '-';
  }else if( S_ISDIR(iMode) ){
    z[0] = 'd';
  }else{
    z[0] = '?';
  }
  for(i=0; i<3; i++){
    int m = (iMode >> ((2-i)*3));
    char *a = &z[1 + i*3];
    a[0] = (m & 0x4) ? 'r' : '-';
    a[1] = (m & 0x2) ? 'w' : '-';
    a[2] = (m & 0x1) ? 'x' : '-';
  }
  z[10] = '\0';
  sqlite3_result_text(context, z, -1, SQLITE_TRANSIENT);
}

#ifndef SQLITE_OMIT_VIRTUALTABLE

/* 
** Cursor type for recursively iterating through a directory structure.
*/
typedef struct fsdir_cursor fsdir_cursor;
typedef struct FsdirLevel FsdirLevel;

struct FsdirLevel {
  DIR *pDir;                 /* From opendir() */
  char *zDir;                /* Name of directory (nul-terminated) */
};

struct fsdir_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */

  int nLvl;                  /* Number of entries in aLvl[] array */
  int iLvl;                  /* Index of current entry */
  FsdirLevel *aLvl;          /* Hierarchy of directories being traversed */

  const char *zBase;
  int nBase;

  struct stat sStat;         /* Current lstat() results */
  char *zPath;               /* Path to current entry */
  sqlite3_int64 iRowid;      /* Current rowid */
};

typedef struct fsdir_tab fsdir_tab;
struct fsdir_tab {
  sqlite3_vtab base;         /* Base class - must be first */
};

/*
** Construct a new fsdir virtual table object.
*/
static int fsdirConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  fsdir_tab *pNew = 0;
  int rc;

  rc = sqlite3_declare_vtab(db, "CREATE TABLE x" FSDIR_SCHEMA);
  if( rc==SQLITE_OK ){
    pNew = (fsdir_tab*)sqlite3_malloc( sizeof(*pNew) );
    if( pNew==0 ) return SQLITE_NOMEM;
    memset(pNew, 0, sizeof(*pNew));
  }
  *ppVtab = (sqlite3_vtab*)pNew;
  return rc;
}

/*
** This method is the destructor for fsdir vtab objects.
*/
static int fsdirDisconnect(sqlite3_vtab *pVtab){
  sqlite3_free(pVtab);
  return SQLITE_OK;
}

/*
** Constructor for a new fsdir_cursor object.
*/
static int fsdirOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  fsdir_cursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  pCur->iLvl = -1;
  *ppCursor = &pCur->base;
  return SQLITE_OK;
}

/*
** Reset a cursor back to the state it was in when first returned
** by fsdirOpen().
*/
static void fsdirResetCursor(fsdir_cursor *pCur){
  int i;
  for(i=0; i<=pCur->iLvl; i++){
    FsdirLevel *pLvl = &pCur->aLvl[i];
    if( pLvl->pDir ) closedir(pLvl->pDir);
    sqlite3_free(pLvl->zDir);
  }
  sqlite3_free(pCur->zPath);
  pCur->aLvl = 0;
  pCur->zPath = 0;
  pCur->zBase = 0;
  pCur->nBase = 0;
  pCur->iLvl = -1;
  pCur->iRowid = 1;
}

/*
** Destructor for an fsdir_cursor.
*/
static int fsdirClose(sqlite3_vtab_cursor *cur){
  fsdir_cursor *pCur = (fsdir_cursor*)cur;

  fsdirResetCursor(pCur);
  sqlite3_free(pCur->aLvl);
  sqlite3_free(pCur);
  return SQLITE_OK;
}

/*
** Set the error message for the virtual table associated with cursor
** pCur to the results of vprintf(zFmt, ...).
*/
static void fsdirSetErrmsg(fsdir_cursor *pCur, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);
  pCur->base.pVtab->zErrMsg = sqlite3_vmprintf(zFmt, ap);
  va_end(ap);
}


/*
** Advance an fsdir_cursor to its next row of output.
*/
static int fsdirNext(sqlite3_vtab_cursor *cur){
  fsdir_cursor *pCur = (fsdir_cursor*)cur;
  mode_t m = pCur->sStat.st_mode;

  pCur->iRowid++;
  if( S_ISDIR(m) ){
    /* Descend into this directory */
    int iNew = pCur->iLvl + 1;
    FsdirLevel *pLvl;
    if( iNew>=pCur->nLvl ){
      int nNew = iNew+1;
      int nByte = nNew*sizeof(FsdirLevel);
      FsdirLevel *aNew = (FsdirLevel*)sqlite3_realloc(pCur->aLvl, nByte);
      if( aNew==0 ) return SQLITE_NOMEM;
      memset(&aNew[pCur->nLvl], 0, sizeof(FsdirLevel)*(nNew-pCur->nLvl));
      pCur->aLvl = aNew;
      pCur->nLvl = nNew;
    }
    pCur->iLvl = iNew;
    pLvl = &pCur->aLvl[iNew];
    
    pLvl->zDir = pCur->zPath;
    pCur->zPath = 0;
    pLvl->pDir = opendir(pLvl->zDir);
    if( pLvl->pDir==0 ){
      fsdirSetErrmsg(pCur, "cannot read directory: %s", pCur->zPath);
      return SQLITE_ERROR;
    }
  }

  while( pCur->iLvl>=0 ){
    FsdirLevel *pLvl = &pCur->aLvl[pCur->iLvl];
    struct dirent *pEntry = readdir(pLvl->pDir);
    if( pEntry ){
      if( pEntry->d_name[0]=='.' ){
       if( pEntry->d_name[1]=='.' && pEntry->d_name[2]=='\0' ) continue;
       if( pEntry->d_name[1]=='\0' ) continue;
      }
      sqlite3_free(pCur->zPath);
      pCur->zPath = sqlite3_mprintf("%s/%s", pLvl->zDir, pEntry->d_name);
      if( pCur->zPath==0 ) return SQLITE_NOMEM;
      if( lstat(pCur->zPath, &pCur->sStat) ){
        fsdirSetErrmsg(pCur, "cannot stat file: %s", pCur->zPath);
        return SQLITE_ERROR;
      }
      return SQLITE_OK;
    }
    closedir(pLvl->pDir);
    sqlite3_free(pLvl->zDir);
    pLvl->pDir = 0;
    pLvl->zDir = 0;
    pCur->iLvl--;
  }

  /* EOF */
  sqlite3_free(pCur->zPath);
  pCur->zPath = 0;
  return SQLITE_OK;
}

/*
** Return values of columns for the row at which the series_cursor
** is currently pointing.
*/
static int fsdirColumn(
  sqlite3_vtab_cursor *cur,   /* The cursor */
  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
  int i                       /* Which column to return */
){
  fsdir_cursor *pCur = (fsdir_cursor*)cur;
  switch( i ){
    case 0: { /* name */
      sqlite3_result_text(ctx, &pCur->zPath[pCur->nBase], -1, SQLITE_TRANSIENT);
      break;
    }

    case 1: /* mode */
      sqlite3_result_int64(ctx, pCur->sStat.st_mode);
      break;

    case 2: /* mtime */
      sqlite3_result_int64(ctx, pCur->sStat.st_mtime);
      break;

    case 3: { /* data */
      mode_t m = pCur->sStat.st_mode;
      if( S_ISDIR(m) ){
        sqlite3_result_null(ctx);
#if !defined(_WIN32) && !defined(WIN32)
      }else if( S_ISLNK(m) ){
        char aStatic[64];
        char *aBuf = aStatic;
        int nBuf = 64;
        int n;

        while( 1 ){
          n = readlink(pCur->zPath, aBuf, nBuf);
          if( n<nBuf ) break;
          if( aBuf!=aStatic ) sqlite3_free(aBuf);
          nBuf = nBuf*2;
          aBuf = sqlite3_malloc(nBuf);
          if( aBuf==0 ){
            sqlite3_result_error_nomem(ctx);
            return SQLITE_NOMEM;
          }
        }

        sqlite3_result_text(ctx, aBuf, n, SQLITE_TRANSIENT);
        if( aBuf!=aStatic ) sqlite3_free(aBuf);
#endif
      }else{
        readFileContents(ctx, pCur->zPath);
      }
    }
  }
  return SQLITE_OK;
}

/*
** Return the rowid for the current row. In this implementation, the
** first row returned is assigned rowid value 1, and each subsequent
** row a value 1 more than that of the previous.
*/
static int fsdirRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  fsdir_cursor *pCur = (fsdir_cursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int fsdirEof(sqlite3_vtab_cursor *cur){
  fsdir_cursor *pCur = (fsdir_cursor*)cur;
  return (pCur->zPath==0);
}

/*
** xFilter callback.
*/
static int fsdirFilter(
  sqlite3_vtab_cursor *cur, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  const char *zDir = 0;
  fsdir_cursor *pCur = (fsdir_cursor*)cur;

  fsdirResetCursor(pCur);

  if( idxNum==0 ){
    fsdirSetErrmsg(pCur, "table function fsdir requires an argument");
    return SQLITE_ERROR;
  }

  assert( argc==idxNum && (argc==1 || argc==2) );
  zDir = (const char*)sqlite3_value_text(argv[0]);
  if( zDir==0 ){
    fsdirSetErrmsg(pCur, "table function fsdir requires a non-NULL argument");
    return SQLITE_ERROR;
  }
  if( argc==2 ){
    pCur->zBase = (const char*)sqlite3_value_text(argv[1]);
  }
  if( pCur->zBase ){
    pCur->nBase = (int)strlen(pCur->zBase)+1;
    pCur->zPath = sqlite3_mprintf("%s/%s", pCur->zBase, zDir);
  }else{
    pCur->zPath = sqlite3_mprintf("%s", zDir);
  }

  if( pCur->zPath==0 ){
    return SQLITE_NOMEM;
  }
  if( lstat(pCur->zPath, &pCur->sStat) ){
    fsdirSetErrmsg(pCur, "cannot stat file: %s", pCur->zPath);
    return SQLITE_ERROR;
  }

  return SQLITE_OK;
}

/*
** SQLite will invoke this method one or more times while planning a query
** that uses the generate_series virtual table.  This routine needs to create
** a query plan for each invocation and compute an estimated cost for that
** plan.
**
** In this implementation idxNum is used to represent the
** query plan.  idxStr is unused.
**
** The query plan is represented by bits in idxNum:
**
**  (1)  start = $value  -- constraint exists
**  (2)  stop = $value   -- constraint exists
**  (4)  step = $value   -- constraint exists
**  (8)  output in descending order
*/
static int fsdirBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  int i;                 /* Loop over constraints */
  int idx4 = -1;
  int idx5 = -1;

  const struct sqlite3_index_constraint *pConstraint;
  pConstraint = pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
    if( pConstraint->usable==0 ) continue;
    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    if( pConstraint->iColumn==4 ) idx4 = i;
    if( pConstraint->iColumn==5 ) idx5 = i;
  }

  if( idx4<0 ){
    pIdxInfo->idxNum = 0;
    pIdxInfo->estimatedCost = (double)(((sqlite3_int64)1) << 50);
  }else{
    pIdxInfo->aConstraintUsage[idx4].omit = 1;
    pIdxInfo->aConstraintUsage[idx4].argvIndex = 1;
    if( idx5>=0 ){
      pIdxInfo->aConstraintUsage[idx5].omit = 1;
      pIdxInfo->aConstraintUsage[idx5].argvIndex = 2;
      pIdxInfo->idxNum = 2;
      pIdxInfo->estimatedCost = 10.0;
    }else{
      pIdxInfo->idxNum = 1;
      pIdxInfo->estimatedCost = 100.0;
    }
  }

  return SQLITE_OK;
}

/*
** Register the "fsdir" virtual table.
*/
static int fsdirRegister(sqlite3 *db){
  static sqlite3_module fsdirModule = {
    0,                         /* iVersion */
    0,                         /* xCreate */
    fsdirConnect,              /* xConnect */
    fsdirBestIndex,            /* xBestIndex */
    fsdirDisconnect,           /* xDisconnect */
    0,                         /* xDestroy */
    fsdirOpen,                 /* xOpen - open a cursor */
    fsdirClose,                /* xClose - close a cursor */
    fsdirFilter,               /* xFilter - configure scan constraints */
    fsdirNext,                 /* xNext - advance a cursor */
    fsdirEof,                  /* xEof - check for end of scan */
    fsdirColumn,               /* xColumn - read data */
    fsdirRowid,                /* xRowid - read data */
    0,                         /* xUpdate */
    0,                         /* xBegin */
    0,                         /* xSync */
    0,                         /* xCommit */
    0,                         /* xRollback */
    0,                         /* xFindMethod */
    0,                         /* xRename */
  };

  int rc = sqlite3_create_module(db, "fsdir", &fsdirModule, 0);
  return rc;
}
#else         /* SQLITE_OMIT_VIRTUALTABLE */
# define fsdirRegister(x) SQLITE_OK
#endif

#ifdef _WIN32
__declspec(dllexport)
#endif
int sqlite3_fileio_init(
  sqlite3 *db, 
  char **pzErrMsg, 
  const sqlite3_api_routines *pApi
){
  int rc = SQLITE_OK;
  SQLITE_EXTENSION_INIT2(pApi);
  (void)pzErrMsg;  /* Unused parameter */
  rc = sqlite3_create_function(db, "readfile", 1, SQLITE_UTF8, 0,
                               readfileFunc, 0, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "writefile", -1, SQLITE_UTF8, 0,
                                 writefileFunc, 0, 0);
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "lsmode", 1, SQLITE_UTF8, 0,
                                 lsModeFunc, 0, 0);
  }
  if( rc==SQLITE_OK ){
    rc = fsdirRegister(db);
  }
  return rc;
}