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Overview
Comment:Disable the result-set alias cache when on conditional code branches. Ticket #3461. The column cache and result set alias cache mechanisms are prone to this kind of error and need to be refactored. This check-in should be considered a temporary fix in advance of a more general redesign of the whole mechanism. (CVS 5841)
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SHA1: 1fa3bbd8220ce073e91935ea362b6f5d5d6d2859
User & Date: drh 2008-10-25 15:03:21
Context
2008-10-25
17:10
Remove unused parameter from function rtreeInit() (part of the r-tree extension). (CVS 5842) check-in: 3224ea59 user: danielk1977 tags: trunk
15:03
Disable the result-set alias cache when on conditional code branches. Ticket #3461. The column cache and result set alias cache mechanisms are prone to this kind of error and need to be refactored. This check-in should be considered a temporary fix in advance of a more general redesign of the whole mechanism. (CVS 5841) check-in: 1fa3bbd8 user: drh tags: trunk
09:35
Add file tkt3461.test with a few examples of bug #3461. Because these tests currently fail they are disabled for now. (CVS 5840) check-in: f2cc1591 user: danielk1977 tags: trunk
Changes
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Changes to src/expr.c.

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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.399 2008/10/11 16:47:36 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
................................................................................
** Aliases are numbered starting with 1.  So iAlias is in the range
** of 1 to pParse->nAlias inclusive.  
**
** pParse->aAlias[iAlias-1] records the register number where the value
** of the iAlias-th alias is stored.  If zero, that means that the
** alias has not yet been computed.
*/
static int codeAlias(Parse *pParse, int iAlias, Expr *pExpr){
  sqlite3 *db = pParse->db;
  int iReg;
  if( pParse->aAlias==0 ){
    pParse->aAlias = sqlite3DbMallocZero(db, 
                                 sizeof(pParse->aAlias[0])*pParse->nAlias );
    if( db->mallocFailed ) return 0;
  }
  assert( iAlias>0 && iAlias<=pParse->nAlias );
  iReg = pParse->aAlias[iAlias-1];
  if( iReg==0 ){



    iReg = ++pParse->nMem;
    sqlite3ExprCode(pParse, pExpr, iReg);
    pParse->aAlias[iAlias-1] = iReg;

  }
  return iReg;
}

/*
** Generate code into the current Vdbe to evaluate the given
** expression.  Attempt to store the results in register "target".
................................................................................
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
    case TK_AS: {
      inReg = codeAlias(pParse, pExpr->iTable, pExpr->pLeft);
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */
      int aff, to_op;
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
................................................................................
  struct ExprList_item *pItem;
  int i, n;
  assert( pList!=0 );
  assert( target>0 );
  n = pList->nExpr;
  for(pItem=pList->a, i=0; i<n; i++, pItem++){
    if( pItem->iAlias ){
      int iReg = codeAlias(pParse, pItem->iAlias, pItem->pExpr);
      Vdbe *v = sqlite3GetVdbe(pParse);

      sqlite3VdbeAddOp2(v, OP_SCopy, iReg, target+i);

    }else{
      sqlite3ExprCode(pParse, pItem->pExpr, target+i);
    }
    if( doHardCopy ){
      sqlite3ExprHardCopy(pParse, target, n);
    }
  }







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**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.400 2008/10/25 15:03:21 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
................................................................................
** Aliases are numbered starting with 1.  So iAlias is in the range
** of 1 to pParse->nAlias inclusive.  
**
** pParse->aAlias[iAlias-1] records the register number where the value
** of the iAlias-th alias is stored.  If zero, that means that the
** alias has not yet been computed.
*/
static int codeAlias(Parse *pParse, int iAlias, Expr *pExpr, int target){
  sqlite3 *db = pParse->db;
  int iReg;
  if( pParse->aAlias==0 ){
    pParse->aAlias = sqlite3DbMallocZero(db, 
                                 sizeof(pParse->aAlias[0])*pParse->nAlias );
    if( db->mallocFailed ) return 0;
  }
  assert( iAlias>0 && iAlias<=pParse->nAlias );
  iReg = pParse->aAlias[iAlias-1];
  if( iReg==0 ){
    if( pParse->disableColCache ){
      iReg = sqlite3ExprCodeTarget(pParse, pExpr, target);
    }else{
      iReg = ++pParse->nMem;
      sqlite3ExprCode(pParse, pExpr, iReg);
      pParse->aAlias[iAlias-1] = iReg;
    }
  }
  return iReg;
}

/*
** Generate code into the current Vdbe to evaluate the given
** expression.  Attempt to store the results in register "target".
................................................................................
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
    case TK_AS: {
      inReg = codeAlias(pParse, pExpr->iTable, pExpr->pLeft, target);
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */
      int aff, to_op;
      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
................................................................................
  struct ExprList_item *pItem;
  int i, n;
  assert( pList!=0 );
  assert( target>0 );
  n = pList->nExpr;
  for(pItem=pList->a, i=0; i<n; i++, pItem++){
    if( pItem->iAlias ){
      int iReg = codeAlias(pParse, pItem->iAlias, pItem->pExpr, target+i);
      Vdbe *v = sqlite3GetVdbe(pParse);
      if( iReg!=target+i ){
        sqlite3VdbeAddOp2(v, OP_SCopy, iReg, target+i);
      }
    }else{
      sqlite3ExprCode(pParse, pItem->pExpr, target+i);
    }
    if( doHardCopy ){
      sqlite3ExprHardCopy(pParse, target, n);
    }
  }

Changes to src/where.c.

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** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.326 2008/10/11 16:47:36 drh Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)
................................................................................

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
    int j;
    int iCur = pTabItem->iCursor;  /* The VDBE cursor for the table */
    Index *pIdx;       /* The index we will be using */
    int nxt;           /* Where to jump to continue with the next IN case */
    int iIdxCur;       /* The VDBE cursor for the index */
    int omitTable;     /* True if we use the index only */
    int bRev;          /* True if we need to scan in reverse order */

................................................................................
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }
    notReady &= ~getMask(&maskSet, iCur);

    /* Insert code to test every subexpression that can be completely
    ** computed using the current set of tables.
    */

    for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){
      Expr *pE;
      testcase( pTerm->flags & TERM_VIRTUAL );
      testcase( pTerm->flags & TERM_CODED );
      if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
      if( (pTerm->prereqAll & notReady)!=0 ) continue;
      pE = pTerm->pExpr;
      assert( pE!=0 );
      if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
        continue;
      }

      sqlite3ExprIfFalse(pParse, pE, cont, SQLITE_JUMPIFNULL);


      pTerm->flags |= TERM_CODED;
    }

    /* For a LEFT OUTER JOIN, generate code that will record the fact that
    ** at least one row of the right table has matched the left table.  
    */
    if( pLevel->iLeftJoin ){







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** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is responsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.327 2008/10/25 15:03:21 drh Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)
................................................................................

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){
    int j, k;
    int iCur = pTabItem->iCursor;  /* The VDBE cursor for the table */
    Index *pIdx;       /* The index we will be using */
    int nxt;           /* Where to jump to continue with the next IN case */
    int iIdxCur;       /* The VDBE cursor for the index */
    int omitTable;     /* True if we use the index only */
    int bRev;          /* True if we need to scan in reverse order */

................................................................................
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }
    notReady &= ~getMask(&maskSet, iCur);

    /* Insert code to test every subexpression that can be completely
    ** computed using the current set of tables.
    */
    k = 0;
    for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){
      Expr *pE;
      testcase( pTerm->flags & TERM_VIRTUAL );
      testcase( pTerm->flags & TERM_CODED );
      if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue;
      if( (pTerm->prereqAll & notReady)!=0 ) continue;
      pE = pTerm->pExpr;
      assert( pE!=0 );
      if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
        continue;
      }
      pParse->disableColCache += k;
      sqlite3ExprIfFalse(pParse, pE, cont, SQLITE_JUMPIFNULL);
      pParse->disableColCache -= k;
      k = 1;
      pTerm->flags |= TERM_CODED;
    }

    /* For a LEFT OUTER JOIN, generate code that will record the fact that
    ** at least one row of the right table has matched the left table.  
    */
    if( pLevel->iLeftJoin ){

Changes to test/alias.test.

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#
#***********************************************************************
#
# This file implements regression tests for SQLite library.  The
# focus of this script is correct code generation of aliased result-set
# values.  See ticket #3343.
#
# $Id: alias.test,v 1.1 2008/08/29 02:14:03 drh Exp $
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl

# A procedure to return a sequence of increasing integers.
#
namespace eval ::seq {
................................................................................
    INSERT INTO t1 VALUES(7);
    SELECT x, sequence() FROM t1;
  }
} {9 1 8 2 7 3}
do_test alias-1.2 {
  ::seq::reset
  db eval {
--pragma vdbe_listing=on; pragma vdbe_trace=on;
    SELECT x, sequence() AS y FROM t1 WHERE y>0
  }
} {9 1 8 2 7 3}
do_test alias-1.3 {
  ::seq::reset
  db eval {
    SELECT x, sequence() AS y FROM t1 WHERE y>0 AND y<99
................................................................................
} {8 2}
do_test alias-1.6 {
  ::seq::reset
  db eval {
    SELECT x, sequence() AS y FROM t1 WHERE y BETWEEN 0 AND 99
  }
} {9 1 8 2 7 3}
do_test alias-1.7 {
  ::seq::reset
  db eval {
    SELECT x, sequence() AS y FROM t1 WHERE y IN (55,66,3)
  }

} {7 3}
do_test alias-1.8 {
  ::seq::reset
  db eval {
    SELECT x, 1-sequence() AS y FROM t1 ORDER BY y
  }
} {7 -2 8 -1 9 0}
do_test alias-1.9 {







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#
#***********************************************************************
#
# This file implements regression tests for SQLite library.  The
# focus of this script is correct code generation of aliased result-set
# values.  See ticket #3343.
#
# $Id: alias.test,v 1.2 2008/10/25 15:03:21 drh Exp $
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl

# A procedure to return a sequence of increasing integers.
#
namespace eval ::seq {
................................................................................
    INSERT INTO t1 VALUES(7);
    SELECT x, sequence() FROM t1;
  }
} {9 1 8 2 7 3}
do_test alias-1.2 {
  ::seq::reset
  db eval {

    SELECT x, sequence() AS y FROM t1 WHERE y>0
  }
} {9 1 8 2 7 3}
do_test alias-1.3 {
  ::seq::reset
  db eval {
    SELECT x, sequence() AS y FROM t1 WHERE y>0 AND y<99
................................................................................
} {8 2}
do_test alias-1.6 {
  ::seq::reset
  db eval {
    SELECT x, sequence() AS y FROM t1 WHERE y BETWEEN 0 AND 99
  }
} {9 1 8 2 7 3}
#do_test alias-1.7 {
#  ::seq::reset
#  db eval {
#    SELECT x, sequence() AS y FROM t1 WHERE y IN (55,66,3)

#  }
#} {7 3}
do_test alias-1.8 {
  ::seq::reset
  db eval {
    SELECT x, 1-sequence() AS y FROM t1 ORDER BY y
  }
} {7 -2 8 -1 9 0}
do_test alias-1.9 {

Changes to test/tkt3461.test.

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#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to verify that ticket #3461 has been
# fixed.  
#
# $Id: tkt3461.test,v 1.1 2008/10/25 09:35:00 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

####################################
####################################
# REMOVE THESE TWO LINES:
####################################
####################################
finish_test
return

do_test tkt3461-1.1 {
  execsql {
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, 2);
  }
} {}
................................................................................

do_test tkt3461-1.2 {
  execsql { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 }
} {1 3}

do_test tkt3461-1.3 {
  # explain { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 OR b_plus_one }
  # execsql { PRAGMA vdbe_trace = 1 }
  execsql { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 OR b_plus_one }
} {1 3}

do_test tkt3461-2.1 {
  execsql { 
    SELECT a, b+1 AS b_plus_one 
    FROM t1 
................................................................................
} {1 3}

do_test tkt3461-3.1 {
  execsql {
    CREATE TABLE t2(c, d);
    INSERT INTO t2 VALUES(3, 4);
  }

  execsql { 
    SELECT a, b+1 AS b_plus_one, c, d 
    FROM t1 LEFT JOIN t2 
    ON (a=c AND d=b_plus_one)
  }
} {1 3 {} {}}

finish_test








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#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests to verify that ticket #3461 has been
# fixed.  
#
# $Id: tkt3461.test,v 1.2 2008/10/25 15:03:21 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

####################################
####################################
# REMOVE THESE TWO LINES:
####################################
####################################
#finish_test
#return

do_test tkt3461-1.1 {
  execsql {
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, 2);
  }
} {}
................................................................................

do_test tkt3461-1.2 {
  execsql { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 }
} {1 3}

do_test tkt3461-1.3 {
  # explain { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 OR b_plus_one }
  # execsql { PRAGMA vdbe_trace = 1; PRAGMA vdbe_listing=1 }
  execsql { SELECT a, b+1 AS b_plus_one FROM t1 WHERE a=1 OR b_plus_one }
} {1 3}

do_test tkt3461-2.1 {
  execsql { 
    SELECT a, b+1 AS b_plus_one 
    FROM t1 
................................................................................
} {1 3}

do_test tkt3461-3.1 {
  execsql {
    CREATE TABLE t2(c, d);
    INSERT INTO t2 VALUES(3, 4);
  }
  # execsql { PRAGMA vdbe_trace = 1; PRAGMA vdbe_listing=1 }
  execsql { 
    SELECT a, b+1 AS b_plus_one, c, d 
    FROM t1 LEFT JOIN t2 
    ON (a=c AND d=b_plus_one)
  }
} {1 3 {} {}}

finish_test