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set ::VERBOSE 0
set ::G(lSelect) [list] ;# List of SELECT statements to analyze
set ::G(database) "" ;# Name of database or SQL schema file
set ::G(trace) [list] ;# List of data from xTrace()
set ::G(verbose) 0 ;# True if -verbose option was passed
proc usage {} {
puts stderr "Usage: $::argv0 ?SWITCHES? DATABASE/SCHEMA"
puts stderr " Switches are:"
puts stderr " -select SQL (recommend indexes for SQL statement)"
puts stderr " -verbose (increase verbosity of output)"
puts stderr " -test (run internal tests and then exit)"
puts stderr ""
exit
}
proc process_cmdline_args {argv} {
global G
proc process_cmdline_args {ctxvar argv} {
upvar $ctxvar G
set nArg [llength $argv]
set G(database) [lindex $argv end]
for {set i 0} {$i < [llength $argv]-1} {incr i} {
set k [lindex $argv $i]
switch -- $k {
-select {
incr i
if {$i>=[llength $argv]-1} usage
lappend G(lSelect) [lindex $argv $i]
}
-verbose {
set G(verbose) 1
set ::VERBOSE 1
}
-test {
sqlidx_internal_tests
}
default {
usage
}
}
}
}
proc open_database {} {
if {$G(database)=="-test"} {
sqlidx_internal_tests
}
}
proc open_database {ctxvar} {
global G
upvar $ctxvar G
sqlite3 db ""
# Check if the "database" file is really an SQLite database. If so, copy
# it into the temp db just opened. Otherwise, assume that it is an SQL
# schema and execute it directly.
set fd [open $G(database)]
set hdr [read $fd 16]
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} else {
append hdr [read $fd]
db eval $hdr
close $fd
}
}
proc analyze_selects {} {
global G
proc analyze_selects {ctxvar} {
upvar $ctxvar G
set G(trace) ""
# Collect a line of xTrace output for each loop in the set of SELECT
# statements.
proc xTrace {zMsg} { lappend ::G(trace) $zMsg }
db trace "lappend ::G(trace)"
proc xTrace {zMsg} {
upvar G G
lappend G(trace) $zMsg
}
db trace xTrace
foreach s $G(lSelect) {
set stmt [sqlite3_prepare_v2 db $s -1 dummy]
set rc [sqlite3_finalize $stmt]
if {$rc!="SQLITE_OK"} {
error "Failed to compile SQL: [sqlite3_errmsg db]"
}
}
db trace ""
if {$G(verbose)} {
if {$::VERBOSE} {
foreach t $G(trace) { puts "trace: $t" }
}
# puts $G(trace)
}
# The argument is a list of the form:
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return $ll
}
#--------------------------------------------------------------------------
# Formulate a CREATE INDEX statement that creates an index on table $tname.
#
proc eqset_to_index {tname eqset {range {}}} {
global G
proc eqset_to_index {ctxvar tname eqset {range {}}} {
upvar $ctxvar G
set lCols [list]
set idxname $tname
foreach e [concat [lsort $eqset] [list $range]] {
foreach e [lsort $eqset] {
if {[llength $e]==0} continue
foreach {c collate} $e {}
lappend lCols "$c collate $collate"
append idxname "_$c"
if {[string compare -nocase binary $collate]!=0} {
append idxname [string tolower $collate]
}
}
foreach {c collate dir} $range {
append idxname "_$c"
if {[string compare -nocase binary $collate]!=0} {
append idxname [string tolower $collate]
}
if {$dir=="DESC"} {
lappend lCols "$c collate $collate DESC"
append idxname "desc"
} else {
lappend lCols "$c collate $collate"
}
}
set create_index "CREATE INDEX $idxname ON ${tname}("
append create_index [join $lCols ", "]
append create_index ");"
set G(trial.$idxname) $create_index
}
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}
set lRet $lNew
}
}
return $lRet
}
proc find_trial_indexes {} {
global G
proc find_trial_indexes {ctxvar} {
upvar $ctxvar G
foreach t $G(trace) {
set tname [lindex $t 0]
catch { array unset mask }
set orderby [list]
if {[lindex $t end 0]=="orderby"} {
set orderby [lrange [lindex $t end] 1 end]
}
foreach lCons [expand_or_cons [lrange $t 2 end]] {
# Populate the array mask() so that it contains an entry for each
# combination of prerequisite scans that may lead to distinct sets
set constraints [list]
# of constraints being usable.
#
catch { array unset mask }
set mask(0) 1
foreach a $lCons {
set type [lindex $a 0]
if {$type=="eq" || $type=="range"} {
set m [lindex $a 3]
foreach k [array names mask] { set mask([expr ($k & $m)]) 1 }
set mask($m) 1
lappend constraints $a
}
}
# Loop once for each distinct prerequisite scan mask identified in
# the previous block.
#
foreach k [array names mask] {
# Identify the constraints available for prerequisite mask $k. For
# each == constraint, set an entry in the eq() array as follows:
#
# set eq(<col>) <collation>
#
# If there is more than one == constraint for a column, and they use
# different collation sequences, <collation> is replaced with a list
# of the possible collation sequences. For example, for:
#
# SELECT * FROM t1 WHERE a=? COLLATE BINARY AND a=? COLLATE NOCASE
#
# Set the following entry in the eq() array:
#
# set eq(a) {binary nocase}
#
# For each range constraint found an entry is appended to the $ranges
# list. The entry is itself a list of the form {<col> <collation>}.
#
catch {array unset eq}
set ranges [list]
foreach a $constraints {
foreach {type col collate m} $a {
if {($m & $k)==$m} {
if {$type=="eq"} {
lappend eq($col) $collate
} else {
set range($col.$collate) 1
foreach a $lCons {
set type [lindex $a 0]
if {$type=="eq" || $type=="range"} {
foreach {type col collate m} $a {
if {($m & $k)==$m} {
if {$type=="eq"} {
lappend eq($col) $collate
} else {
lappend ranges [list $col $collate ASC]
}
}
}
}
}
set ranges [lsort -unique $ranges]
if {$orderby != ""} {
lappend ranges $orderby
}
#puts "mask=$k eq=[array get eq] range=[array get range]"
set ranges [array names range]
foreach eqset [expand_eq_list [array get eq]] {
if {[llength $ranges]==0} {
eqset_to_index $tname $eqset
} else {
foreach r $ranges {
set bSeen 0
foreach {c collate} [split $r .] {}
if {$eqset != ""} {
eqset_to_index G $tname $eqset
}
foreach r $ranges {
set tail [list]
foreach {c collate dir} $r {
set bSeen 0
foreach e $eqset {
if {[lindex $e 0] == $c} {
set bSeen 1
break
}
}
if {$bSeen} {
if {$bSeen==0} { lappend tail {*}$r }
eqset_to_index $tname $eqset
} else {
eqset_to_index $tname $eqset [list $c $collate]
}
}
if {[llength $tail]} {
eqset_to_index G $tname $eqset $r
}
}
}
}
}
}
if {$G(verbose)} {
if {$::VERBOSE} {
foreach k [array names G trial.*] { puts "index: $G($k)" }
}
}
proc run_trials {} {
global G
proc run_trials {ctxvar} {
upvar $ctxvar G
set ret [list]
foreach k [array names G trial.*] {
set idxname [lindex [split $k .] 1]
db eval $G($k)
set pgno [db one {SELECT rootpage FROM sqlite_master WHERE name = $idxname}]
set IDX($pgno) $idxname
}
db eval ANALYZE
catch { array unset used }
foreach s $G(lSelect) {
db eval "EXPLAIN $s" x {
if {($x(opcode)=="OpenRead" || $x(opcode)=="ReopenIdx")} {
if {[info exists IDX($x(p2))]} { set used($IDX($x(p2))) 1 }
}
}
foreach idx [array names used] {
puts $G(trial.$idx)
lappend ret $G(trial.$idx)
}
}
}
process_cmdline_args $argv
open_database
analyze_selects
find_trial_indexes
run_trials
set ret
}
proc sqlidx_init_context {varname} {
upvar $varname G
set G(lSelect) [list] ;# List of SELECT statements to analyze
set G(database) "" ;# Name of database or SQL schema file
set G(trace) [list] ;# List of data from xTrace()
}
#-------------------------------------------------------------------------
# The following is test code only.
#
proc sqlidx_one_test {tn schema select expected} {
# if {$tn!=2} return
sqlidx_init_context C
sqlite3 db ""
db eval $schema
lappend C(lSelect) $select
analyze_selects C
find_trial_indexes C
set idxlist [run_trials C]
if {$idxlist != [list {*}$expected]} {
puts stderr "Test $tn failed"
puts stderr "Expected: $expected"
puts stderr "Got: $idxlist"
exit -1
}
db close
}
proc sqlidx_internal_tests {} {
# No indexes for a query with no constraints.
sqlidx_one_test 0 {
CREATE TABLE t1(a, b, c);
} {
SELECT * FROM t1;
} {
}
sqlidx_one_test 1 {
CREATE TABLE t1(a, b, c);
CREATE TABLE t2(x, y, z);
} {
SELECT a FROM t1, t2 WHERE a=? AND x=c
} {
{CREATE INDEX t2_x ON t2(x collate BINARY);}
{CREATE INDEX t1_a_c ON t1(a collate BINARY, c collate BINARY);}
}
sqlidx_one_test 2 {
CREATE TABLE t1(a, b, c);
} {
SELECT * FROM t1 WHERE b>?;
} {
{CREATE INDEX t1_b ON t1(b collate BINARY);}
}
sqlidx_one_test 3 {
CREATE TABLE t1(a, b, c);
} {
SELECT * FROM t1 WHERE b COLLATE nocase BETWEEN ? AND ?
} {
{CREATE INDEX t1_bnocase ON t1(b collate NOCASE);}
}
sqlidx_one_test 4 {
CREATE TABLE t1(a, b, c);
} {
SELECT a FROM t1 ORDER BY b;
} {
{CREATE INDEX t1_b ON t1(b collate BINARY);}
}
sqlidx_one_test 5 {
CREATE TABLE t1(a, b, c);
} {
SELECT a FROM t1 WHERE a=? ORDER BY b;
} {
{CREATE INDEX t1_a_b ON t1(a collate BINARY, b collate BINARY);}
}
sqlidx_one_test 5 {
CREATE TABLE t1(a, b, c);
} {
SELECT min(a) FROM t1
} {
{CREATE INDEX t1_a ON t1(a collate BINARY);}
}
sqlidx_one_test 6 {
CREATE TABLE t1(a, b, c);
} {
SELECT * FROM t1 ORDER BY a ASC, b COLLATE nocase DESC, c ASC;
} {
{CREATE INDEX t1_a_bnocasedesc_c ON t1(a collate BINARY, b collate NOCASE DESC, c collate BINARY);}
}
exit
}
# End of internal test code.
#-------------------------------------------------------------------------
sqlidx_init_context D
process_cmdline_args D $argv
open_database D
analyze_selects D
find_trial_indexes D
foreach idx [run_trials D] { puts $idx }
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