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Overview
Comment:Modify the query planner interface so that it always passes in the result set. This is the first step toward adding an optimization that will omit tables from a join that do not contribute to the result.
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SHA1: 2c2577e69ccb47f1af674a755e71221e2ca0b322
User & Date: drh 2013-06-21 00:35:37
Context
2013-06-21
02:05
Attempt to disable inner loops of a join that do not generate output. This does not work, since the inner loops might run zero times and thus inhibit all output. Needs to be enhanced to work only for LEFT JOINs or when we know that the inner loop will always run at least once. check-in: ca839723 user: drh tags: omit-join-table-opt
00:35
Modify the query planner interface so that it always passes in the result set. This is the first step toward adding an optimization that will omit tables from a join that do not contribute to the result. check-in: 2c2577e6 user: drh tags: omit-join-table-opt
2013-06-20
17:32
Add a NEVER() macro and an explanation comment around an unreachable branch in the STAT3 logic. check-in: 604c3c5d user: drh tags: nextgen-query-plan-exp
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/select.c.

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    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

  if( !isAgg && pGroupBy==0 ){
    /* No aggregate functions and no GROUP BY clause */
    ExprList *pDist = (sDistinct.isTnct ? p->pEList : 0);

    /* Begin the database scan. */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pOrderBy, pDist, 0,0);

    if( pWInfo==0 ) goto select_end;
    if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){
      p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo);
    }
    if( sqlite3WhereIsDistinct(pWInfo) ){
      sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo);
    }
    if( pOrderBy && sqlite3WhereIsOrdered(pWInfo) ) pOrderBy = 0;

    /* If sorting index that was created by a prior OP_OpenEphemeral 
    ** instruction ended up not being needed, then change the OP_OpenEphemeral
    ** into an OP_Noop.







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    sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED;
  }else{
    sDistinct.eTnctType = WHERE_DISTINCT_NOOP;
  }

  if( !isAgg && pGroupBy==0 ){
    /* No aggregate functions and no GROUP BY clause */
    u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0);

    /* Begin the database scan. */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pOrderBy, p->pEList,
                               wctrlFlags, 0);
    if( pWInfo==0 ) goto select_end;
    if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){
      p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo);
    }
    if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){
      sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo);
    }
    if( pOrderBy && sqlite3WhereIsOrdered(pWInfo) ) pOrderBy = 0;

    /* If sorting index that was created by a prior OP_OpenEphemeral 
    ** instruction ended up not being needed, then change the OP_OpenEphemeral
    ** into an OP_Noop.

Changes to src/sqliteInt.h.

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#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN_CLOSE  0x0010 /* Table cursors are already open */
#define WHERE_FORCE_TABLE      0x0020 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0040 /* Only code the 1st table in pTabList */
#define WHERE_AND_ONLY         0x0080 /* Don't use indices for OR terms */
#define WHERE_GROUPBY          0x0100 /* pOrderBy is really a GROUP BY */
#define WHERE_DISTINCTBY       0x0200 /* pOrderby is really a DISTINCT clause */


/* Allowed return values from sqlite3WhereIsDistinct()
*/
#define WHERE_DISTINCT_NOOP      0  /* DISTINCT keyword not used */
#define WHERE_DISTINCT_UNIQUE    1  /* No duplicates */
#define WHERE_DISTINCT_ORDERED   2  /* All duplicates are adjacent */
#define WHERE_DISTINCT_UNORDERED 3  /* Duplicates are scattered */







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#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN_CLOSE  0x0010 /* Table cursors are already open */
#define WHERE_FORCE_TABLE      0x0020 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0040 /* Only code the 1st table in pTabList */
#define WHERE_AND_ONLY         0x0080 /* Don't use indices for OR terms */
#define WHERE_GROUPBY          0x0100 /* pOrderBy is really a GROUP BY */
#define WHERE_DISTINCTBY       0x0200 /* pOrderby is really a DISTINCT clause */
#define WHERE_WANT_DISTINCT    0x0400 /* All output needs to be distinct */

/* Allowed return values from sqlite3WhereIsDistinct()
*/
#define WHERE_DISTINCT_NOOP      0  /* DISTINCT keyword not used */
#define WHERE_DISTINCT_UNIQUE    1  /* No duplicates */
#define WHERE_DISTINCT_ORDERED   2  /* All duplicates are adjacent */
#define WHERE_DISTINCT_UNORDERED 3  /* Duplicates are scattered */

Changes to src/where.c.

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** An instance of this object holds the complete state of the query
** planner.
*/
struct WhereInfo {
  Parse *pParse;            /* Parsing and code generating context */
  SrcList *pTabList;        /* List of tables in the join */
  ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
  ExprList *pDistinct;      /* DISTINCT ON values, or NULL */
  WhereLoop *pLoops;        /* List of all WhereLoop objects */
  Bitmask revMask;          /* Mask of ORDER BY terms that need reversing */
  WhereCost nRowOut;        /* Estimated number of output rows */
  u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
  u8 bOBSat;                /* ORDER BY satisfied by indices */
  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
................................................................................
/*
** Print a WhereLoop object for debugging purposes
*/
static void whereLoopPrint(WhereLoop *p, SrcList *pTabList){
  int nb = 1+(pTabList->nSrc+7)/8;
  struct SrcList_item *pItem = pTabList->a + p->iTab;
  Table *pTab = pItem->pTab;
  sqlite3DebugPrintf("%c %2d.%0*llx.%0*llx", p->cId,
                     p->iTab, nb, p->maskSelf, nb, p->prereq);
  sqlite3DebugPrintf(" %8s",
                     pItem->zAlias ? pItem->zAlias : pTab->zName);
  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
    if( p->u.btree.pIndex ){
      const char *zName = p->u.btree.pIndex->zName;
      if( zName==0 ) zName = "ipk";
      if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){
        int i = sqlite3Strlen30(zName) - 1;
        while( zName[i]!='_' ) i--;
        zName += i;
      }
      sqlite3DebugPrintf(".%-12s %2d", zName, p->u.btree.nEq);
    }else{
      sqlite3DebugPrintf("%16s","");
    }
  }else{
    char *z;
    if( p->u.vtab.idxStr ){
      z = sqlite3_mprintf("(%d,\"%s\",%x)",
                p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask);
    }else{
      z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask);
    }
    sqlite3DebugPrintf(" %-15s", z);
    sqlite3_free(z);
  }
  sqlite3DebugPrintf(" fg %05x N %d", p->wsFlags, p->nLTerm);
  sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
}
#endif

/*
** Convert bulk memory into a valid WhereLoop that can be passed
** to whereLoopClear harmlessly.
................................................................................
  /* Load the lowest cost path into pWInfo */
  for(iLoop=0; iLoop<nLoop; iLoop++){
    WhereLevel *pLevel = pWInfo->a + iLoop;
    pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
    pLevel->iFrom = pWLoop->iTab;
    pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
  }
  if( (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0 
   && pWInfo->pDistinct
   && nRowEst
  ){
    Bitmask notUsed;
    int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pDistinct, pFrom,
                 WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], &notUsed);
    if( rc==1 ) pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
  }
  if( pFrom->isOrdered ){
    if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }else{
................................................................................
  if( pLoop->wsFlags ){
    pLoop->nOut = (WhereCost)1;
    pWInfo->a[0].pWLoop = pLoop;
    pLoop->maskSelf = getMask(&pWInfo->sMaskSet, iCur);
    pWInfo->a[0].iTabCur = iCur;
    pWInfo->nRowOut = 1;
    if( pWInfo->pOrderBy ) pWInfo->bOBSat =  1;

    if( pWInfo->pDistinct ) pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;

#ifdef SQLITE_DEBUG
    pLoop->cId = '0';
#endif
    return 1;
  }
  return 0;
}
................................................................................
**
** pOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
** if there is one.  If there is no ORDER BY clause or if this routine
** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  ExprList *pOrderBy,   /* An ORDER BY clause, or NULL */
  ExprList *pDistinct,  /* The select-list for DISTINCT queries - or NULL */
  u16 wctrlFlags,       /* One of the WHERE_* flags defined in sqliteInt.h */
  int iIdxCur           /* If WHERE_ONETABLE_ONLY is set, index cursor number */
){
  int nByteWInfo;            /* Num. bytes allocated for WhereInfo struct */
  int nTabList;              /* Number of elements in pTabList */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
................................................................................
    pWInfo = 0;
    goto whereBeginError;
  }
  pWInfo->nLevel = nTabList;
  pWInfo->pParse = pParse;
  pWInfo->pTabList = pTabList;
  pWInfo->pOrderBy = pOrderBy;
  pWInfo->pDistinct = pDistinct;
  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
  pWInfo->wctrlFlags = wctrlFlags;
  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
  pMaskSet = &pWInfo->sMaskSet;
  sWLB.pWInfo = pWInfo;
  sWLB.pWC = &pWInfo->sWC;
  sWLB.pNew = (WhereLoop*)&pWInfo->a[nTabList];
................................................................................
  whereLoopInit(sWLB.pNew);
#ifdef SQLITE_DEBUG
  sWLB.pNew->cId = '*';
#endif

  /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
  if( OptimizationDisabled(db, SQLITE_DistinctOpt) ) pDistinct = 0;



  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(&pWInfo->sWC, pWInfo);
  sqlite3ExprCodeConstants(pParse, pWhere);
................................................................................
    pWhere = 0;
  }

  /* Special case: No FROM clause
  */
  if( nTabList==0 ){
    if( pOrderBy ) pWInfo->bOBSat = 1;

    if( pDistinct ) pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;

  }

  /* Assign a bit from the bitmask to every term in the FROM clause.
  **
  ** When assigning bitmask values to FROM clause cursors, it must be
  ** the case that if X is the bitmask for the N-th FROM clause term then
  ** the bitmask for all FROM clause terms to the left of the N-th term
................................................................................
    goto whereBeginError;
  }

  /* If the ORDER BY (or GROUP BY) clause contains references to general
  ** expressions, then we won't be able to satisfy it using indices, so
  ** go ahead and disable it now.
  */
  if( pOrderBy && pDistinct ){
    for(ii=0; ii<pOrderBy->nExpr; ii++){
      Expr *pExpr = sqlite3ExprSkipCollate(pOrderBy->a[ii].pExpr);
      if( pExpr->op!=TK_COLUMN ){
        pWInfo->pOrderBy = pOrderBy = 0;
        break;
      }else if( pExpr->iColumn<0 ){
        break;
      }
    }
  }

  /* Check if the DISTINCT qualifier, if there is one, is redundant. 
  ** If it is, then set pDistinct to NULL and WhereInfo.eDistinct to
  ** WHERE_DISTINCT_UNIQUE to tell the caller to ignore the DISTINCT.
  */
  if( pDistinct ){
    if( isDistinctRedundant(pParse,pTabList,&pWInfo->sWC,pDistinct) ){
      pDistinct = 0;
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }else if( pOrderBy==0 ){
      pWInfo->wctrlFlags |= WHERE_DISTINCTBY;
      pWInfo->pOrderBy = pDistinct;
    }
  }

  /* Construct the WhereLoop objects */
  WHERETRACE(0xffff,("*** Optimizer Start ***\n"));
  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
    rc = whereLoopAddAll(&sWLB);







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** An instance of this object holds the complete state of the query
** planner.
*/
struct WhereInfo {
  Parse *pParse;            /* Parsing and code generating context */
  SrcList *pTabList;        /* List of tables in the join */
  ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
  ExprList *pResultSet;     /* Result set. DISTINCT operates on these */
  WhereLoop *pLoops;        /* List of all WhereLoop objects */
  Bitmask revMask;          /* Mask of ORDER BY terms that need reversing */
  WhereCost nRowOut;        /* Estimated number of output rows */
  u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
  u8 bOBSat;                /* ORDER BY satisfied by indices */
  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
................................................................................
/*
** Print a WhereLoop object for debugging purposes
*/
static void whereLoopPrint(WhereLoop *p, SrcList *pTabList){
  int nb = 1+(pTabList->nSrc+7)/8;
  struct SrcList_item *pItem = pTabList->a + p->iTab;
  Table *pTab = pItem->pTab;
  sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId,
                     p->iTab, nb, p->maskSelf, nb, p->prereq);
  sqlite3DebugPrintf(" %12s",
                     pItem->zAlias ? pItem->zAlias : pTab->zName);
  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
    if( p->u.btree.pIndex ){
      const char *zName = p->u.btree.pIndex->zName;
      if( zName==0 ) zName = "ipk";
      if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){
        int i = sqlite3Strlen30(zName) - 1;
        while( zName[i]!='_' ) i--;
        zName += i;
      }
      sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq);
    }else{
      sqlite3DebugPrintf("%20s","");
    }
  }else{
    char *z;
    if( p->u.vtab.idxStr ){
      z = sqlite3_mprintf("(%d,\"%s\",%x)",
                p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask);
    }else{
      z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask);
    }
    sqlite3DebugPrintf(" %-19s", z);
    sqlite3_free(z);
  }
  sqlite3DebugPrintf(" f %04x N %d", p->wsFlags, p->nLTerm);
  sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
}
#endif

/*
** Convert bulk memory into a valid WhereLoop that can be passed
** to whereLoopClear harmlessly.
................................................................................
  /* Load the lowest cost path into pWInfo */
  for(iLoop=0; iLoop<nLoop; iLoop++){
    WhereLevel *pLevel = pWInfo->a + iLoop;
    pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
    pLevel->iFrom = pWLoop->iTab;
    pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
  }
  if( (pWInfo->wctrlFlags & (WHERE_DISTINCTBY|WHERE_WANT_DISTINCT))
                ==WHERE_WANT_DISTINCT
   && nRowEst
  ){
    Bitmask notUsed;
    int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pResultSet, pFrom,
                 WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], &notUsed);
    if( rc==1 ) pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
  }
  if( pFrom->isOrdered ){
    if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }else{
................................................................................
  if( pLoop->wsFlags ){
    pLoop->nOut = (WhereCost)1;
    pWInfo->a[0].pWLoop = pLoop;
    pLoop->maskSelf = getMask(&pWInfo->sMaskSet, iCur);
    pWInfo->a[0].iTabCur = iCur;
    pWInfo->nRowOut = 1;
    if( pWInfo->pOrderBy ) pWInfo->bOBSat =  1;
    if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }
#ifdef SQLITE_DEBUG
    pLoop->cId = '0';
#endif
    return 1;
  }
  return 0;
}
................................................................................
**
** pOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
** if there is one.  If there is no ORDER BY clause or if this routine
** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* FROM clause: A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  ExprList *pOrderBy,   /* An ORDER BY clause, or NULL */
  ExprList *pResultSet, /* Result set of the query */
  u16 wctrlFlags,       /* One of the WHERE_* flags defined in sqliteInt.h */
  int iIdxCur           /* If WHERE_ONETABLE_ONLY is set, index cursor number */
){
  int nByteWInfo;            /* Num. bytes allocated for WhereInfo struct */
  int nTabList;              /* Number of elements in pTabList */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
................................................................................
    pWInfo = 0;
    goto whereBeginError;
  }
  pWInfo->nLevel = nTabList;
  pWInfo->pParse = pParse;
  pWInfo->pTabList = pTabList;
  pWInfo->pOrderBy = pOrderBy;
  pWInfo->pResultSet = pResultSet;
  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
  pWInfo->wctrlFlags = wctrlFlags;
  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
  pMaskSet = &pWInfo->sMaskSet;
  sWLB.pWInfo = pWInfo;
  sWLB.pWC = &pWInfo->sWC;
  sWLB.pNew = (WhereLoop*)&pWInfo->a[nTabList];
................................................................................
  whereLoopInit(sWLB.pNew);
#ifdef SQLITE_DEBUG
  sWLB.pNew->cId = '*';
#endif

  /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
  if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
    wctrlFlags &= ~WHERE_WANT_DISTINCT;
  }

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(&pWInfo->sWC, pWInfo);
  sqlite3ExprCodeConstants(pParse, pWhere);
................................................................................
    pWhere = 0;
  }

  /* Special case: No FROM clause
  */
  if( nTabList==0 ){
    if( pOrderBy ) pWInfo->bOBSat = 1;
    if( wctrlFlags & WHERE_WANT_DISTINCT ){
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }
  }

  /* Assign a bit from the bitmask to every term in the FROM clause.
  **
  ** When assigning bitmask values to FROM clause cursors, it must be
  ** the case that if X is the bitmask for the N-th FROM clause term then
  ** the bitmask for all FROM clause terms to the left of the N-th term
................................................................................
    goto whereBeginError;
  }

  /* If the ORDER BY (or GROUP BY) clause contains references to general
  ** expressions, then we won't be able to satisfy it using indices, so
  ** go ahead and disable it now.
  */
  if( pOrderBy && (wctrlFlags & WHERE_WANT_DISTINCT)!=0 ){
    for(ii=0; ii<pOrderBy->nExpr; ii++){
      Expr *pExpr = sqlite3ExprSkipCollate(pOrderBy->a[ii].pExpr);
      if( pExpr->op!=TK_COLUMN ){
        pWInfo->pOrderBy = pOrderBy = 0;
        break;
      }else if( pExpr->iColumn<0 ){
        break;
      }
    }
  }

  if( wctrlFlags & WHERE_WANT_DISTINCT ){
    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
      /* The DISTINCT marking is pointless.  Ignore it. */
      wctrlFlags &= ~WHERE_WANT_DISTINCT;
      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
    }else if( pOrderBy==0 ){
      /* Try to ORDER BY the result set to make distinct processing easier */
      pWInfo->wctrlFlags |= WHERE_DISTINCTBY;
      pWInfo->pOrderBy = pResultSet;


    }
  }

  /* Construct the WhereLoop objects */
  WHERETRACE(0xffff,("*** Optimizer Start ***\n"));
  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
    rc = whereLoopAddAll(&sWLB);

Changes to test/alter2.test.

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} {1 2 10 3 4 {} 5 6 {}}
do_test alter2-1.5 {
  execsql {
    CREATE INDEX abc_i ON abc(c);
  }
} {}
do_test alter2-1.6 {

  execsql {
    SELECT c FROM abc ORDER BY c;
  }
} {{} {} 10}
do_test alter2-1.7 {
  execsql {
    SELECT * FROM abc WHERE c = 10;







>







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} {1 2 10 3 4 {} 5 6 {}}
do_test alter2-1.5 {
  execsql {
    CREATE INDEX abc_i ON abc(c);
  }
} {}
do_test alter2-1.6 {
breakpoint
  execsql {
    SELECT c FROM abc ORDER BY c;
  }
} {{} {} 10}
do_test alter2-1.7 {
  execsql {
    SELECT * FROM abc WHERE c = 10;