catch { db close }
  catch { db2 close }
  forcedelete test.db test.db2
  sqlite3 db test.db
  sqlite3 db2 test.db2
}

proc do_common_sql {sql} {
  execsql $sql db
  execsql $sql db2
}
proc xConflict args { return "OMIT" }

proc do_then_apply_sql {sql {dbname main}} {

  sqlite3session S db $dbname
  db eval "SELECT name FROM $dbname.sqlite_master WHERE type = 'table'" {
    S attach $name
  }

  db eval $sql
  sqlite3changeset_apply db2 [S changeset] xConflict
  S delete
}

proc do_iterator_test {tn tbl_list sql res} {
  sqlite3session S db main
  foreach t $tbl_list {S attach $t}
  execsql $sql

  set r [list]
  foreach v $res { lappend r $v }

  set x [list]
  sqlite3session_foreach c [S changeset] { lappend x $c }
  uplevel do_test $tn [list [list set {} $x]] [list $r]

  S delete
}

# Compare the contents of all tables in [db1] and [db2]. Throw an error if 
# they are not identical, or return an empty string if they are.
#
proc compare_db {db1 db2} {

  set sql {SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name}
  set lot1 [$db1 eval $sql]
  set lot2 [$db2 eval $sql]

  if {$lot1 != $lot2} { error "databases contain different tables" }

  foreach tbl $lot1 {
    set col1 [list]
    set col2 [list]

    $db1 eval "PRAGMA table_info = $tbl" { lappend col1 $name }
    $db2 eval "PRAGMA table_info = $tbl" { lappend col2 $name }
    if {$col1 != $col2} { error "table $tbl schema mismatch" }

    set sql "SELECT * FROM $tbl ORDER BY [join $col1 ,]"
    set data1 [$db1 eval $sql]
    set data2 [$db2 eval $sql]
    if {$data1 != $data2} { error "table $tbl data mismatch" }
  }

  return ""
}

##########################################################################
# End of proc definitions. Start of tests.
##########################################################################

test_reset
do_execsql_test 1.0 { 
  CREATE TABLE t1(a PRIMARY KEY, b);
................................................................................
do_iterator_test 1.1 t1 {
  DELETE FROM t1 WHERE a = 'i';
  INSERT INTO t1 VALUES('ii', 'two');
} {
  {DELETE t1 {t i t one} {}} 
  {INSERT t1 {} {t ii t two}}
}
do_iterator_test 1.1 t1 {
  INSERT INTO t1 VALUES(1.5, 99.9)
} {
  {INSERT t1 {} {f 1.5 f 99.9}}
}


# Execute each of the following blocks of SQL on database [db1]. Collect
# changes using a session object. Apply the resulting changeset to
# database [db2]. Then check that the contents of the two databases are
# identical.
#

................................................................................
    INSERT INTO %T1% VALUES(randomblob(21000), randomblob(0));
    INSERT INTO %T1% VALUES(1.5, 1.5);
    INSERT INTO %T1% VALUES(4.56, -99.999999999999999999999);
  }
  12 {
    INSERT INTO %T2% VALUES(NULL, NULL);
  }
































}

test_reset
do_common_sql {
  CREATE TABLE t1(a PRIMARY KEY, b);
  CREATE TABLE t2(a, b INTEGER PRIMARY KEY);
  CREATE TABLE t3(a, b, c, PRIMARY KEY(a, b));
}

foreach {tn sql} [string map {%T1% t1 %T2% t2 %T3% t3} $set_of_tests] {
  do_then_apply_sql $sql
  do_test 1.$tn { compare_db db db2 } {}
}

# The following block of tests is similar to the last, except that the
# session object is recording changes made to an attached database. The
# main database contains a table of the same name as the table being
# modified within the attached db.
#
test_reset
forcedelete test.db3
sqlite3 db3 test.db3
do_test 2.0 {
  execsql {
    ATTACH 'test.db3' AS 'aux';
    CREATE TABLE t1(a, b PRIMARY KEY);
    CREATE TABLE t2(x, y, z);
    CREATE TABLE t3(a);

    CREATE TABLE aux.t1(a PRIMARY KEY, b);
................................................................................

proc xTrace {args} { puts $args }

foreach {tn sql} [
  string map {%T1% aux.t1 %T2% aux.t2 %T3% aux.t3} $set_of_tests
] {
  do_then_apply_sql $sql aux
  do_test 2.$tn { compare_db db3 db2 } {}
}
catch {db3 close}


#-------------------------------------------------------------------------
# The following tests verify that NULL values in primary key columns are
# handled correctly by the session module.
#
test_reset
do_execsql_test 3.0 {
  CREATE TABLE t1(a PRIMARY KEY);
  CREATE TABLE t2(a, b, c, PRIMARY KEY(c, b));
  CREATE TABLE t3(a, b INTEGER PRIMARY KEY);
}

foreach {tn sql changeset} {
  1 {
................................................................................
  5 { INSERT INTO t2 VALUES(1, 2, NULL) }    { }
  6 { INSERT INTO t2 VALUES(1, NULL, 3) }    { }
  7 { INSERT INTO t2 VALUES(1, NULL, NULL) } { }
  8 { INSERT INTO t2 VALUES(1, 2, 3) }       { {INSERT t2 {} {i 1 i 2 i 3}} }
  9 { DELETE FROM t2 WHERE 1 }               { {DELETE t2 {i 1 i 2 i 3} {}} }

} {
  do_iterator_test 3.$tn {t1 t2 t3} $sql $changeset
}


finish_test

  catch { db close }
  catch { db2 close }
  forcedelete test.db test.db2
  sqlite3 db test.db
  sqlite3 db2 test.db2
}






























































##########################################################################
# End of proc definitions. Start of tests.
##########################################################################

test_reset
do_execsql_test 1.0 { 
  CREATE TABLE t1(a PRIMARY KEY, b);
................................................................................
do_iterator_test 1.1 t1 {
  DELETE FROM t1 WHERE a = 'i';
  INSERT INTO t1 VALUES('ii', 'two');
} {
  {DELETE t1 {t i t one} {}} 
  {INSERT t1 {} {t ii t two}}
}
do_iterator_test 1.2 t1 {
  INSERT INTO t1 VALUES(1.5, 99.9)
} {
  {INSERT t1 {} {f 1.5 f 99.9}}
}


# Execute each of the following blocks of SQL on database [db1]. Collect
# changes using a session object. Apply the resulting changeset to
# database [db2]. Then check that the contents of the two databases are
# identical.
#

................................................................................
    INSERT INTO %T1% VALUES(randomblob(21000), randomblob(0));
    INSERT INTO %T1% VALUES(1.5, 1.5);
    INSERT INTO %T1% VALUES(4.56, -99.999999999999999999999);
  }
  12 {
    INSERT INTO %T2% VALUES(NULL, NULL);
  }

  13 {
    DELETE FROM %T1% WHERE 1;

    -- Insert many rows with real primary keys. Enough to force the session
    -- objects hash table to resize. 
    INSERT INTO %T1% VALUES(0.1, 0.1);
    INSERT INTO %T1% SELECT a+0.1, b+0.1 FROM %T1%;
    INSERT INTO %T1% SELECT a+0.2, b+0.2 FROM %T1%;
    INSERT INTO %T1% SELECT a+0.4, b+0.4 FROM %T1%;
    INSERT INTO %T1% SELECT a+0.8, b+0.8 FROM %T1%;
    INSERT INTO %T1% SELECT a+1.6, b+1.6 FROM %T1%;
    INSERT INTO %T1% SELECT a+3.2, b+3.2 FROM %T1%;
    INSERT INTO %T1% SELECT a+6.4, b+6.4 FROM %T1%;
    INSERT INTO %T1% SELECT a+12.8, b+12.8 FROM %T1%;
    INSERT INTO %T1% SELECT a+25.6, b+25.6 FROM %T1%;
    INSERT INTO %T1% SELECT a+51.2, b+51.2 FROM %T1%;
    INSERT INTO %T1% SELECT a+102.4, b+102.4 FROM %T1%;
    INSERT INTO %T1% SELECT a+204.8, b+204.8 FROM %T1%;
  }

  14 {
    DELETE FROM %T1% WHERE 1;
  }

  15 {
    INSERT INTO %T1% VALUES(1, 1);
    INSERT INTO %T1% SELECT a+2, b+2 FROM %T1%;
    INSERT INTO %T1% SELECT a+4, b+4 FROM %T1%;
    INSERT INTO %T1% SELECT a+8, b+8 FROM %T1%;
    INSERT INTO %T1% SELECT a+256, b+256 FROM %T1%;
  }
}

test_reset
do_common_sql {
  CREATE TABLE t1(a PRIMARY KEY, b);
  CREATE TABLE t2(a, b INTEGER PRIMARY KEY);
  CREATE TABLE t3(a, b, c, PRIMARY KEY(a, b));
}

foreach {tn sql} [string map {%T1% t1 %T2% t2 %T3% t3} $set_of_tests] {
  do_then_apply_sql $sql
  do_test 2.$tn { compare_db db db2 } {}
}

# The following block of tests is similar to the last, except that the
# session object is recording changes made to an attached database. The
# main database contains a table of the same name as the table being
# modified within the attached db.
#
test_reset
forcedelete test.db3
sqlite3 db3 test.db3
do_test 3.0 {
  execsql {
    ATTACH 'test.db3' AS 'aux';
    CREATE TABLE t1(a, b PRIMARY KEY);
    CREATE TABLE t2(x, y, z);
    CREATE TABLE t3(a);

    CREATE TABLE aux.t1(a PRIMARY KEY, b);
................................................................................

proc xTrace {args} { puts $args }

foreach {tn sql} [
  string map {%T1% aux.t1 %T2% aux.t2 %T3% aux.t3} $set_of_tests
] {
  do_then_apply_sql $sql aux
  do_test 3.$tn { compare_db db3 db2 } {}
}
catch {db3 close}


#-------------------------------------------------------------------------
# The following tests verify that NULL values in primary key columns are
# handled correctly by the session module.
#
test_reset
do_execsql_test 4.0 {
  CREATE TABLE t1(a PRIMARY KEY);
  CREATE TABLE t2(a, b, c, PRIMARY KEY(c, b));
  CREATE TABLE t3(a, b INTEGER PRIMARY KEY);
}

foreach {tn sql changeset} {
  1 {
................................................................................
  5 { INSERT INTO t2 VALUES(1, 2, NULL) }    { }
  6 { INSERT INTO t2 VALUES(1, NULL, 3) }    { }
  7 { INSERT INTO t2 VALUES(1, NULL, NULL) } { }
  8 { INSERT INTO t2 VALUES(1, 2, 3) }       { {INSERT t2 {} {i 1 i 2 i 3}} }
  9 { DELETE FROM t2 WHERE 1 }               { {DELETE t2 {i 1 i 2 i 3} {}} }

} {
  do_iterator_test 4.$tn {t1 t2 t3} $sql $changeset
}


finish_test

proc do_conflict_test {tn args} {
  proc xConflict {args} { 
    lappend ::xConflict $args
    return "" 
  }
  proc bgerror {args} { set ::background_error $args }


  set O(-tables)    [list]
  set O(-sql)       [list]
  set O(-conflicts) [list]

  array set V $args
  foreach key [array names V] {
    if {![info exists O($key)]} {error "no such option: $key"}
  }
  array set O $args

  sqlite3session S db main
  foreach t $O(-tables) { S attach $t }
  execsql $O(-sql)

  set ::xConflict [list]
  sqlite3changeset_apply db2 [S changeset] xConflict

  set conflicts [list]
  foreach c $O(-conflicts) {
    lappend conflicts $c
  }

  after 1 {set go 1}
  vwait go

  uplevel do_test $tn [list { set ::xConflict }] [list $conflicts]
  S delete
}

proc do_common_sql {sql} {
  execsql $sql db
  execsql $sql db2
}

proc do_then_apply_sql {sql {dbname main}} {
  proc xConflict args { return "OMIT" }

  set rc [catch {
    sqlite3session S db $dbname
    db eval "SELECT name FROM $dbname.sqlite_master WHERE type = 'table'" {
      S attach $name
    }
    db eval $sql
    sqlite3changeset_apply db2 [S changeset] xConflict
  } msg]

  catch { S delete }

  if {$rc} {error $msg}
}

proc do_iterator_test {tn tbl_list sql res} {
  sqlite3session S db main
  foreach t $tbl_list {S attach $t}
  execsql $sql

  set r [list]
  foreach v $res { lappend r $v }

  set x [list]
  sqlite3session_foreach c [S changeset] { lappend x $c }
  uplevel do_test $tn [list [list set {} $x]] [list $r]

  S delete
}

# Compare the contents of all tables in [db1] and [db2]. Throw an error if 
# they are not identical, or return an empty string if they are.
#
proc compare_db {db1 db2} {

  set sql {SELECT name FROM sqlite_master WHERE type = 'table' ORDER BY name}
  set lot1 [$db1 eval $sql]
  set lot2 [$db2 eval $sql]

  if {$lot1 != $lot2} { error "databases contain different tables" }

  foreach tbl $lot1 {
    set col1 [list]
    set col2 [list]

    $db1 eval "PRAGMA table_info = $tbl" { lappend col1 $name }
    $db2 eval "PRAGMA table_info = $tbl" { lappend col2 $name }
    if {$col1 != $col2} { error "table $tbl schema mismatch" }

    set sql "SELECT * FROM $tbl ORDER BY [join $col1 ,]"
    set data1 [$db1 eval $sql]
    set data2 [$db2 eval $sql]
    if {$data1 != $data2} { error "table $tbl data mismatch" }
  }

  return ""
}

# 2011 Mar 21
#
# 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 session module.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source [file join [file dirname [info script]] session_common.tcl]
source $testdir/tester.tcl

set testprefix sessionfault

forcedelete test.db2
sqlite3 db2 test.db2

do_common_sql {
  CREATE TABLE t1(a, b, c, PRIMARY KEY(a, b));
  INSERT INTO t1 VALUES(1, 2, 3);
  INSERT INTO t1 VALUES(4, 5, 6);
}
faultsim_save_and_close
db2 close

# Test OOM error handling when collecting and applying a simple changeset.
#
do_faultsim_test pagerfault-1 -faults oom-* -prep {
  catch {db2 close}
  catch {db close}
  faultsim_restore_and_reopen
  sqlite3 db2 test.db2
} -body {
  do_then_apply_sql {
    INSERT INTO t1 VALUES(7, 8, 9);
    UPDATE t1 SET c = 10 WHERE a = 1;
    DELETE FROM t1 WHERE a = 4;
  }
} -test {
  faultsim_test_result {0 {}} {1 SQLITE_NOMEM}
  faultsim_integrity_check
  if {$testrc==0} { compare_db db db2 }
}

# This test case is designed so that a malloc() failure occurs while
# resizing the session object hash-table from 256 to 512 buckets. This
# is not an error, just a sub-optimal condition.
#
do_faultsim_test pagerfault-2 -faults oom-* -prep {
  catch {db2 close}
  catch {db close}
  faultsim_restore_and_reopen
  sqlite3 db2 test.db2

  sqlite3session S db main
  S attach t1
  execsql { BEGIN }
  for {set i 0} {$i < 125} {incr i} {
    execsql {INSERT INTO t1 VALUES(10+$i, 10+$i, 10+$i)}
  }
} -body {
  for {set i 125} {$i < 133} {incr i} {
    execsql {INSERT INTO t1 VALUES(10+$i, 10+$i, 1-+$i)}
  }
  S changeset
  set {} {}
} -test {
  faultsim_test_result {0 {}} {1 SQLITE_NOMEM}
  if {$testrc==0} { 
    sqlite3changeset_apply db2 [S changeset] xConflict
    compare_db db db2 
  }
  catch { S delete }
  faultsim_integrity_check
}

finish_test

      sqlite3_value *pVal;

      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }


      eType = sqlite3_value_type(pVal);
      h = HASH_APPEND(h, eType);
      switch( eType ){
        case SQLITE_INTEGER: 
        case SQLITE_FLOAT: {
          i64 iVal;
................................................................................
      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }
      if( rc!=SQLITE_OK || sqlite3_value_type(pVal)!=eType ) return rc;

      switch( eType ){
        case SQLITE_INTEGER:
        case SQLITE_FLOAT: {



          i64 iVal = sessionGetI64(a);
          a += 8;
          if( eType==SQLITE_INTEGER ){
            if( sqlite3_value_int64(pVal)!=iVal ) return SQLITE_OK;
          }else{
            double rVal;
            assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
            memcpy(&rVal, &iVal, 8);
            if( sqlite3_value_double(pVal)!=rVal ) return SQLITE_OK;
          }
          break;
        }
        case SQLITE_TEXT:
        case SQLITE_BLOB: {
          int n;
          const u8 *z;
          a += sessionVarintGet(a, &n);
          if( sqlite3_value_bytes(pVal)!=n ) return SQLITE_OK;
          z = eType==SQLITE_TEXT ? 


            sqlite3_value_text(pVal) : sqlite3_value_blob(pVal);

          if( memcmp(a, z, n) ) return SQLITE_OK;
          a += n;
          break;
        }
      }
    }
  }

  *pbEqual = 1;
  return SQLITE_OK;
}
................................................................................
        }else if( 1 || pTab->abPK[i] ){
          rc = sqlite3_preupdate_new(pSession->db, i, &p);
        }
        if( p && rc==SQLITE_OK ){
          rc = sessionSerializeValue(&pChange->aRecord[nByte], p, &nByte);
        }
      }
      pChange->nRecord = nByte;
  
      /* If an error has occurred, mark the session object as failed. */
      if( rc!=SQLITE_OK ){
        sqlite3_free(pChange);
        pSession->rc = rc;
      }else{
        /* Add the change back to the hash-table */

        pChange->bInsert = (op==SQLITE_INSERT);
        pChange->pNext = pTab->apChange[iHash];
        pTab->apChange[iHash] = pChange;


      }
    }
  }





}

/*
** The 'pre-update' hook registered by this module with SQLite databases.
*/
static void xPreUpdate(
  void *pCtx,                     /* Copy of third arg to preupdate_hook() */
................................................................................
      }

      if( rc==SQLITE_OK && nCol!=sqlite3_column_count(pSel) ){
        rc = SQLITE_SCHEMA;
      }

      nNoop = buf.nBuf;
      for(i=0; i<pTab->nChange; i++){
        SessionChange *p;         /* Used to iterate through changes */

        for(p=pTab->apChange[i]; rc==SQLITE_OK && p; p=p->pNext){
          rc = sessionSelectBind(pSel, nCol, abPK, p->aRecord, p->nRecord);
          if( rc==SQLITE_OK ){
            if( sqlite3_step(pSel)==SQLITE_ROW ){
              int iCol;
................................................................................
                sessionAppendUpdate(&buf, pSel, p, abPK, &rc);
              }
            }else if( !p->bInsert ){
              /* A DELETE change */
              sessionAppendByte(&buf, SQLITE_DELETE, &rc);
              sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
            }

            rc = sqlite3_reset(pSel);

          }
        }
      }

      sqlite3_finalize(pSel);

      if( buf.nBuf==nNoop ){
        buf.nBuf = nRewind;
      }
    }
  }

  if( rc==SQLITE_OK ){
................................................................................
**
** This function may not be called on iterators passed to a conflict handler
** callback by changeset_apply().
*/
int sqlite3changeset_finalize(sqlite3_changeset_iter *p){
  int i;                          /* Used to iterate through p->apValue[] */
  int rc = p->rc;                 /* Return code */

  for(i=0; i<p->nCol*2; i++) sqlite3ValueFree(p->apValue[i]);

  sqlite3_free(p->apValue);
  sqlite3_free(p);
  return rc;
}

/*
** Invert a changeset object.
................................................................................
  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
  int rc;                         /* Return code */
  const char *zTab = 0;           /* Name of current table */
  int nTab = 0;                   /* Result of strlen(zTab) */
  SessionApplyCtx sApply;         /* changeset_apply() context object */

  memset(&sApply, 0, sizeof(sApply));
  sqlite3changeset_start(&pIter, nChangeset, pChangeset);


  sqlite3_mutex_enter(sqlite3_db_mutex(db));
  rc = sqlite3_exec(db, "SAVEPOINT changeset_apply", 0, 0, 0);
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3changeset_next(pIter) ){
    int nCol;
    int op;
    int bReplace = 0;

      sqlite3_value *pVal;

      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }
      if( rc!=SQLITE_OK ) return rc;

      eType = sqlite3_value_type(pVal);
      h = HASH_APPEND(h, eType);
      switch( eType ){
        case SQLITE_INTEGER: 
        case SQLITE_FLOAT: {
          i64 iVal;
................................................................................
      if( bNew ){
        rc = sqlite3_preupdate_new(db, i, &pVal);
      }else{
        rc = sqlite3_preupdate_old(db, i, &pVal);
      }
      if( rc!=SQLITE_OK || sqlite3_value_type(pVal)!=eType ) return rc;

      /* A SessionChange object never has a NULL value in a PK column */
      assert( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT
           || eType==SQLITE_BLOB    || eType==SQLITE_TEXT
      );

      if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
        i64 iVal = sessionGetI64(a);
        a += 8;
        if( eType==SQLITE_INTEGER ){
          if( sqlite3_value_int64(pVal)!=iVal ) return SQLITE_OK;
        }else{
          double rVal;
          assert( sizeof(iVal)==8 && sizeof(rVal)==8 );
          memcpy(&rVal, &iVal, 8);
          if( sqlite3_value_double(pVal)!=rVal ) return SQLITE_OK;
        }



      }else{
        int n;
        const u8 *z;
        a += sessionVarintGet(a, &n);
        if( sqlite3_value_bytes(pVal)!=n ) return SQLITE_OK;
        if( eType==SQLITE_TEXT ){
          z = sqlite3_value_text(pVal);
        }else{
          z = sqlite3_value_blob(pVal);
        }
        if( memcmp(a, z, n) ) return SQLITE_OK;
        a += n;
        break;

      }
    }
  }

  *pbEqual = 1;
  return SQLITE_OK;
}
................................................................................
        }else if( 1 || pTab->abPK[i] ){
          rc = sqlite3_preupdate_new(pSession->db, i, &p);
        }
        if( p && rc==SQLITE_OK ){
          rc = sessionSerializeValue(&pChange->aRecord[nByte], p, &nByte);
        }
      }



      if( rc==SQLITE_OK ){



        /* Add the change back to the hash-table */
        pChange->nRecord = nByte;
        pChange->bInsert = (op==SQLITE_INSERT);
        pChange->pNext = pTab->apChange[iHash];
        pTab->apChange[iHash] = pChange;
      }else{
        sqlite3_free(pChange);
      }
    }
  }

  /* If an error has occurred, mark the session object as failed. */
  if( rc!=SQLITE_OK ){
    pSession->rc = rc;
  }
}

/*
** The 'pre-update' hook registered by this module with SQLite databases.
*/
static void xPreUpdate(
  void *pCtx,                     /* Copy of third arg to preupdate_hook() */
................................................................................
      }

      if( rc==SQLITE_OK && nCol!=sqlite3_column_count(pSel) ){
        rc = SQLITE_SCHEMA;
      }

      nNoop = buf.nBuf;
      for(i=0; i<pTab->nChange && rc==SQLITE_OK; i++){
        SessionChange *p;         /* Used to iterate through changes */

        for(p=pTab->apChange[i]; rc==SQLITE_OK && p; p=p->pNext){
          rc = sessionSelectBind(pSel, nCol, abPK, p->aRecord, p->nRecord);
          if( rc==SQLITE_OK ){
            if( sqlite3_step(pSel)==SQLITE_ROW ){
              int iCol;
................................................................................
                sessionAppendUpdate(&buf, pSel, p, abPK, &rc);
              }
            }else if( !p->bInsert ){
              /* A DELETE change */
              sessionAppendByte(&buf, SQLITE_DELETE, &rc);
              sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
            }
            if( rc==SQLITE_OK ){
              rc = sqlite3_reset(pSel);
            }
          }
        }
      }

      sqlite3_finalize(pSel);

      if( buf.nBuf==nNoop ){
        buf.nBuf = nRewind;
      }
    }
  }

  if( rc==SQLITE_OK ){
................................................................................
**
** This function may not be called on iterators passed to a conflict handler
** callback by changeset_apply().
*/
int sqlite3changeset_finalize(sqlite3_changeset_iter *p){
  int i;                          /* Used to iterate through p->apValue[] */
  int rc = p->rc;                 /* Return code */
  if( p->apValue ){
    for(i=0; i<p->nCol*2; i++) sqlite3ValueFree(p->apValue[i]);
  }
  sqlite3_free(p->apValue);
  sqlite3_free(p);
  return rc;
}

/*
** Invert a changeset object.
................................................................................
  sqlite3_changeset_iter *pIter;  /* Iterator to skip through changeset */  
  int rc;                         /* Return code */
  const char *zTab = 0;           /* Name of current table */
  int nTab = 0;                   /* Result of strlen(zTab) */
  SessionApplyCtx sApply;         /* changeset_apply() context object */

  memset(&sApply, 0, sizeof(sApply));
  rc = sqlite3changeset_start(&pIter, nChangeset, pChangeset);
  if( rc!=SQLITE_OK ) return rc;

  sqlite3_mutex_enter(sqlite3_db_mutex(db));
  rc = sqlite3_exec(db, "SAVEPOINT changeset_apply", 0, 0, 0);
  while( rc==SQLITE_OK && SQLITE_ROW==sqlite3changeset_next(pIter) ){
    int nCol;
    int op;
    int bReplace = 0;

  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_old_out;
  }

  /* If the old.* record has not yet been loaded into memory, do so now. */
  if( p->pUnpacked==0 ){
    u32 nRecord;
    u8 *aRecord;

    rc = sqlite3BtreeDataSize(p->pCsr->pCursor, &nRecord);
    if( rc!=SQLITE_OK ) goto preupdate_old_out;
    aRecord = sqlite3DbMallocRaw(db, nRecord);
    if( !aRecord ) goto preupdate_old_out;
    rc = sqlite3BtreeData(p->pCsr->pCursor, 0, nRecord, aRecord);




    if( rc!=SQLITE_OK ){
      sqlite3DbFree(db, aRecord);
      goto preupdate_old_out;
    }

    p->pUnpacked = sqlite3VdbeRecordUnpack(&p->keyinfo, nRecord, aRecord, 0, 0);
    p->aRecord = aRecord;
  }

  if( iIdx>=p->pUnpacked->nField ){
    *ppValue = (sqlite3_value *)columnNullValue();
  }else{
    *ppValue = &p->pUnpacked->aMem[iIdx];
    if( iIdx==p->iPKey ){

  if( iIdx>=p->pCsr->nField || iIdx<0 ){
    rc = SQLITE_RANGE;
    goto preupdate_old_out;
  }

  /* If the old.* record has not yet been loaded into memory, do so now. */
  if( p->pUnpacked==0 ){
    u32 nRec;
    u8 *aRec;

    rc = sqlite3BtreeDataSize(p->pCsr->pCursor, &nRec);
    if( rc!=SQLITE_OK ) goto preupdate_old_out;
    aRec = sqlite3DbMallocRaw(db, nRec);
    if( !aRec ) goto preupdate_old_out;
    rc = sqlite3BtreeData(p->pCsr->pCursor, 0, nRec, aRec);
    if( rc==SQLITE_OK ){
      p->pUnpacked = sqlite3VdbeRecordUnpack(&p->keyinfo, nRec, aRec, 0, 0);
      if( !p->pUnpacked ) rc = SQLITE_NOMEM;
    }
    if( rc!=SQLITE_OK ){
      sqlite3DbFree(db, aRec);
      goto preupdate_old_out;
    }


    p->aRecord = aRec;
  }

  if( iIdx>=p->pUnpacked->nField ){
    *ppValue = (sqlite3_value *)columnNullValue();
  }else{
    *ppValue = &p->pUnpacked->aMem[iIdx];
    if( iIdx==p->iPKey ){