/ Check-in [f7ba0219]
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Experimental changes to improve optimization of DISTINCT queries.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | experimental
Files: files | file ages | folders
SHA1: f7ba0219ef2f235543c258be736955d91ca5ecce
User & Date: dan 2011-06-30 20:17:15
Context
2011-07-01
14:21
Improvements and tests for detection of redundant DISTINCT qualifiers. check-in: 7337293c user: dan tags: experimental
2011-06-30
20:17
Experimental changes to improve optimization of DISTINCT queries. check-in: f7ba0219 user: dan tags: experimental
2011-06-29
17:11
Pass the BTREE_UNORDERED hint into both sqlite3BtreeOpen() and into sqlite3BtreeCreateTable(). check-in: 591de898 user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/delete.c.

367
368
369
370
371
372
373
374


375
376
377
378
379
380
381
    int iRowSet = ++pParse->nMem;   /* Register for rowset of rows to delete */
    int iRowid = ++pParse->nMem;    /* Used for storing rowid values. */
    int regRowid;                   /* Actual register containing rowids */

    /* Collect rowids of every row to be deleted.
    */
    sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0,WHERE_DUPLICATES_OK);


    if( pWInfo==0 ) goto delete_from_cleanup;
    regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid);
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid);
    if( db->flags & SQLITE_CountRows ){
      sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
    }
    sqlite3WhereEnd(pWInfo);







|
>
>







367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
    int iRowSet = ++pParse->nMem;   /* Register for rowset of rows to delete */
    int iRowid = ++pParse->nMem;    /* Used for storing rowid values. */
    int regRowid;                   /* Actual register containing rowids */

    /* Collect rowids of every row to be deleted.
    */
    sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
    pWInfo = sqlite3WhereBegin(
        pParse, pTabList, pWhere, 0, 0, WHERE_DUPLICATES_OK
    );
    if( pWInfo==0 ) goto delete_from_cleanup;
    regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid);
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid);
    if( db->flags & SQLITE_CountRows ){
      sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
    }
    sqlite3WhereEnd(pWInfo);

Changes to src/fkey.c.

556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
  sNameContext.pParse = pParse;
  sqlite3ResolveExprNames(&sNameContext, pWhere);

  /* Create VDBE to loop through the entries in pSrc that match the WHERE
  ** clause. If the constraint is not deferred, throw an exception for
  ** each row found. Otherwise, for deferred constraints, increment the
  ** deferred constraint counter by nIncr for each row selected.  */
  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0);
  if( nIncr>0 && pFKey->isDeferred==0 ){
    sqlite3ParseToplevel(pParse)->mayAbort = 1;
  }
  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  if( pWInfo ){
    sqlite3WhereEnd(pWInfo);
  }







|







556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
  sNameContext.pParse = pParse;
  sqlite3ResolveExprNames(&sNameContext, pWhere);

  /* Create VDBE to loop through the entries in pSrc that match the WHERE
  ** clause. If the constraint is not deferred, throw an exception for
  ** each row found. Otherwise, for deferred constraints, increment the
  ** deferred constraint counter by nIncr for each row selected.  */
  pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0);
  if( nIncr>0 && pFKey->isDeferred==0 ){
    sqlite3ParseToplevel(pParse)->mayAbort = 1;
  }
  sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  if( pWInfo ){
    sqlite3WhereEnd(pWInfo);
  }

Changes to src/select.c.

3717
3718
3719
3720
3721
3722
3723

3724
3725
3726
3727
3728
3729
3730
....
3846
3847
3848
3849
3850
3851
3852

3853
3854
3855
3856
3857
3858

3859
3860
3861
3862
3863
3864
3865
....
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919

3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934







































3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
....
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
....
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
  ExprList *pOrderBy;    /* The ORDER BY clause.  May be NULL */
  ExprList *pGroupBy;    /* The GROUP BY clause.  May be NULL */
  Expr *pHaving;         /* The HAVING clause.  May be NULL */
  int isDistinct;        /* True if the DISTINCT keyword is present */
  int distinct;          /* Table to use for the distinct set */
  int rc = 1;            /* Value to return from this function */
  int addrSortIndex;     /* Address of an OP_OpenEphemeral instruction */

  AggInfo sAggInfo;      /* Information used by aggregate queries */
  int iEnd;              /* Address of the end of the query */
  sqlite3 *db;           /* The database connection */

#ifndef SQLITE_OMIT_EXPLAIN
  int iRestoreSelectId = pParse->iSelectId;
  pParse->iSelectId = pParse->iNextSelectId++;
................................................................................
    return rc;
  }
#endif

  /* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
  ** GROUP BY might use an index, DISTINCT never does.
  */

  assert( p->pGroupBy==0 || (p->selFlags & SF_Aggregate)!=0 );
  if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ){
    p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
    pGroupBy = p->pGroupBy;
    p->selFlags &= ~SF_Distinct;
  }


  /* If there is both a GROUP BY and an ORDER BY clause and they are
  ** identical, then disable the ORDER BY clause since the GROUP BY
  ** will cause elements to come out in the correct order.  This is
  ** an optimization - the correct answer should result regardless.
  ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER
  ** to disable this optimization for testing purposes.
................................................................................
  p->nSelectRow = (double)LARGEST_INT64;
  computeLimitRegisters(pParse, p, iEnd);

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    KeyInfo *pKeyInfo;
    assert( isAgg || pGroupBy );
    distinct = pParse->nTab++;
    pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
    sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
                        (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
  }else{
    distinct = -1;
  }

  /* Aggregate and non-aggregate queries are handled differently */
  if( !isAgg && pGroupBy==0 ){
    /* This case is for non-aggregate queries

    ** Begin the database scan
    */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, 0);
    if( pWInfo==0 ) goto select_end;
    if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut;

    /* 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.
    */
    if( addrSortIndex>=0 && pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
      p->addrOpenEphm[2] = -1;
    }








































    /* Use the standard inner loop
    */
    assert(!isDistinct);
    selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, -1, pDest,
                    pWInfo->iContinue, pWInfo->iBreak);

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
    /* This is the processing for aggregate queries */
................................................................................

      /* Begin a loop that will extract all source rows in GROUP BY order.
      ** This might involve two separate loops with an OP_Sort in between, or
      ** it might be a single loop that uses an index to extract information
      ** in the right order to begin with.
      */
      sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
      pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0);
      if( pWInfo==0 ) goto select_end;
      if( pGroupBy==0 ){
        /* The optimizer is able to deliver rows in group by order so
        ** we do not have to sort.  The OP_OpenEphemeral table will be
        ** cancelled later because we still need to use the pKeyInfo
        */
        pGroupBy = p->pGroupBy;
................................................................................
        }
  
        /* This case runs if the aggregate has no GROUP BY clause.  The
        ** processing is much simpler since there is only a single row
        ** of output.
        */
        resetAccumulator(pParse, &sAggInfo);
        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, flag);
        if( pWInfo==0 ){
          sqlite3ExprListDelete(db, pDel);
          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);
        if( !pMinMax && flag ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);







>







 







>






>







 







<


|
|







|
>
|
<
|












>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
|
<
<
|







 







|







 







|







3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
....
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
....
3903
3904
3905
3906
3907
3908
3909

3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923

3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976


3977
3978
3979
3980
3981
3982
3983
3984
....
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
....
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
  ExprList *pOrderBy;    /* The ORDER BY clause.  May be NULL */
  ExprList *pGroupBy;    /* The GROUP BY clause.  May be NULL */
  Expr *pHaving;         /* The HAVING clause.  May be NULL */
  int isDistinct;        /* True if the DISTINCT keyword is present */
  int distinct;          /* Table to use for the distinct set */
  int rc = 1;            /* Value to return from this function */
  int addrSortIndex;     /* Address of an OP_OpenEphemeral instruction */
  int addrDistinctIndex; /* Address of an OP_OpenEphemeral instruction */
  AggInfo sAggInfo;      /* Information used by aggregate queries */
  int iEnd;              /* Address of the end of the query */
  sqlite3 *db;           /* The database connection */

#ifndef SQLITE_OMIT_EXPLAIN
  int iRestoreSelectId = pParse->iSelectId;
  pParse->iSelectId = pParse->iNextSelectId++;
................................................................................
    return rc;
  }
#endif

  /* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
  ** GROUP BY might use an index, DISTINCT never does.
  */
#if 0
  assert( p->pGroupBy==0 || (p->selFlags & SF_Aggregate)!=0 );
  if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ){
    p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
    pGroupBy = p->pGroupBy;
    p->selFlags &= ~SF_Distinct;
  }
#endif

  /* If there is both a GROUP BY and an ORDER BY clause and they are
  ** identical, then disable the ORDER BY clause since the GROUP BY
  ** will cause elements to come out in the correct order.  This is
  ** an optimization - the correct answer should result regardless.
  ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER
  ** to disable this optimization for testing purposes.
................................................................................
  p->nSelectRow = (double)LARGEST_INT64;
  computeLimitRegisters(pParse, p, iEnd);

  /* Open a virtual index to use for the distinct set.
  */
  if( p->selFlags & SF_Distinct ){
    KeyInfo *pKeyInfo;

    distinct = pParse->nTab++;
    pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
    addrDistinctIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
        (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
  }else{
    distinct = -1;
  }

  /* Aggregate and non-aggregate queries are handled differently */
  if( !isAgg && pGroupBy==0 ){
    ExprList *pDist = (isDistinct ? p->pEList : 0);

    /* Begin the database scan. */

    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, pDist, 0);
    if( pWInfo==0 ) goto select_end;
    if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut;

    /* 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.
    */
    if( addrSortIndex>=0 && pOrderBy==0 ){
      sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
      p->addrOpenEphm[2] = -1;
    }

    if( pWInfo->eDistinct ){
      assert( isDistinct );
      assert( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED 
           || pWInfo->eDistinct==WHERE_DISTINCT_UNIQUE 
      );
      distinct = -1;
      if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED ){
        int iJump;
        int iExpr;
        int iFlag = ++pParse->nMem;
        int iBase = pParse->nMem+1;
        int iBase2 = iBase + pEList->nExpr;
        pParse->nMem += (pEList->nExpr*2);
        VdbeOp *pOp;

        /* Change the OP_OpenEphemeral coded earlier to an OP_Integer. The
        ** OP_Integer initializes the "first row" flag.  */
        pOp = sqlite3VdbeGetOp(v, addrDistinctIndex);
        pOp->opcode = OP_Integer;
        pOp->p1 = 1;
        pOp->p2 = iFlag;

        sqlite3ExprCodeExprList(pParse, pEList, iBase, 1);
        iJump = sqlite3VdbeCurrentAddr(v) + 1 + pEList->nExpr + 1 + 1;
        sqlite3VdbeAddOp2(v, OP_If, iFlag, iJump-1);
        for(iExpr=0; iExpr<pEList->nExpr; iExpr++){
          CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[iExpr].pExpr);
          sqlite3VdbeAddOp3(v, OP_Ne, iBase+iExpr, iJump, iBase2+iExpr);
          sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
          sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iContinue);

        sqlite3VdbeAddOp2(v, OP_Integer, 0, iFlag);
        assert( sqlite3VdbeCurrentAddr(v)==iJump );
        sqlite3VdbeAddOp3(v, OP_Move, iBase, iBase2, pEList->nExpr);
      }
    }

    /* Use the standard inner loop. */


    selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, pDest,
                    pWInfo->iContinue, pWInfo->iBreak);

    /* End the database scan loop.
    */
    sqlite3WhereEnd(pWInfo);
  }else{
    /* This is the processing for aggregate queries */
................................................................................

      /* Begin a loop that will extract all source rows in GROUP BY order.
      ** This might involve two separate loops with an OP_Sort in between, or
      ** it might be a single loop that uses an index to extract information
      ** in the right order to begin with.
      */
      sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
      pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0, 0);
      if( pWInfo==0 ) goto select_end;
      if( pGroupBy==0 ){
        /* The optimizer is able to deliver rows in group by order so
        ** we do not have to sort.  The OP_OpenEphemeral table will be
        ** cancelled later because we still need to use the pKeyInfo
        */
        pGroupBy = p->pGroupBy;
................................................................................
        }
  
        /* This case runs if the aggregate has no GROUP BY clause.  The
        ** processing is much simpler since there is only a single row
        ** of output.
        */
        resetAccumulator(pParse, &sAggInfo);
        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, 0, flag);
        if( pWInfo==0 ){
          sqlite3ExprListDelete(db, pDel);
          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);
        if( !pMinMax && flag ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);

Changes to src/sqliteInt.h.

1962
1963
1964
1965
1966
1967
1968

1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979



1980
1981
1982
1983
1984
1985
1986
....
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
** into the second half to give some continuity.
*/
struct WhereInfo {
  Parse *pParse;       /* Parsing and code generating context */
  u16 wctrlFlags;      /* Flags originally passed to sqlite3WhereBegin() */
  u8 okOnePass;        /* Ok to use one-pass algorithm for UPDATE or DELETE */
  u8 untestedTerms;    /* Not all WHERE terms resolved by outer loop */

  SrcList *pTabList;             /* List of tables in the join */
  int iTop;                      /* The very beginning of the WHERE loop */
  int iContinue;                 /* Jump here to continue with next record */
  int iBreak;                    /* Jump here to break out of the loop */
  int nLevel;                    /* Number of nested loop */
  struct WhereClause *pWC;       /* Decomposition of the WHERE clause */
  double savedNQueryLoop;        /* pParse->nQueryLoop outside the WHERE loop */
  double nRowOut;                /* Estimated number of output rows */
  WhereLevel a[1];               /* Information about each nest loop in WHERE */
};




/*
** A NameContext defines a context in which to resolve table and column
** names.  The context consists of a list of tables (the pSrcList) field and
** a list of named expression (pEList).  The named expression list may
** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
** to the table being operated on by INSERT, UPDATE, or DELETE.  The
** pEList corresponds to the result set of a SELECT and is NULL for
................................................................................
int sqlite3IsReadOnly(Parse*, Table*, int);
void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *);
#endif
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**, u16);
void sqlite3WhereEnd(WhereInfo*);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int);
void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
void sqlite3ExprCodeMove(Parse*, int, int, int);
void sqlite3ExprCodeCopy(Parse*, int, int, int);
void sqlite3ExprCacheStore(Parse*, int, int, int);
void sqlite3ExprCachePush(Parse*);







>











>
>
>







 







|







1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
....
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
** into the second half to give some continuity.
*/
struct WhereInfo {
  Parse *pParse;       /* Parsing and code generating context */
  u16 wctrlFlags;      /* Flags originally passed to sqlite3WhereBegin() */
  u8 okOnePass;        /* Ok to use one-pass algorithm for UPDATE or DELETE */
  u8 untestedTerms;    /* Not all WHERE terms resolved by outer loop */
  u8 eDistinct;
  SrcList *pTabList;             /* List of tables in the join */
  int iTop;                      /* The very beginning of the WHERE loop */
  int iContinue;                 /* Jump here to continue with next record */
  int iBreak;                    /* Jump here to break out of the loop */
  int nLevel;                    /* Number of nested loop */
  struct WhereClause *pWC;       /* Decomposition of the WHERE clause */
  double savedNQueryLoop;        /* pParse->nQueryLoop outside the WHERE loop */
  double nRowOut;                /* Estimated number of output rows */
  WhereLevel a[1];               /* Information about each nest loop in WHERE */
};

#define WHERE_DISTINCT_UNIQUE 1
#define WHERE_DISTINCT_ORDERED 2

/*
** A NameContext defines a context in which to resolve table and column
** names.  The context consists of a list of tables (the pSrcList) field and
** a list of named expression (pEList).  The named expression list may
** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
** to the table being operated on by INSERT, UPDATE, or DELETE.  The
** pEList corresponds to the result set of a SELECT and is NULL for
................................................................................
int sqlite3IsReadOnly(Parse*, Table*, int);
void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
Expr *sqlite3LimitWhere(Parse *, SrcList *, Expr *, ExprList *, Expr *, Expr *, char *);
#endif
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**,ExprList*,u16);
void sqlite3WhereEnd(WhereInfo*);
int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int);
void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
void sqlite3ExprCodeMove(Parse*, int, int, int);
void sqlite3ExprCodeCopy(Parse*, int, int, int);
void sqlite3ExprCacheStore(Parse*, int, int, int);
void sqlite3ExprCachePush(Parse*);

Changes to src/update.c.

307
308
309
310
311
312
313
314


315
316
317
318
319
320
321
  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  /* Begin the database scan
  */
  sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid);
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0, WHERE_ONEPASS_DESIRED);


  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  /* Remember the rowid of every item to be updated.
  */
  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid);
  if( !okOnePass ){







|
>
>







307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  /* Begin the database scan
  */
  sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid);
  pWInfo = sqlite3WhereBegin(
      pParse, pTabList, pWhere, 0, 0, WHERE_ONEPASS_DESIRED
  );
  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  /* Remember the rowid of every item to be updated.
  */
  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid);
  if( !okOnePass ){

Changes to src/where.c.

249
250
251
252
253
254
255

256
257
258
259
260
261
262
....
1429
1430
1431
1432
1433
1434
1435
1436



1437
1438
1439
1440
1441
1442
1443
....
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
....
2685
2686
2687
2688
2689
2690
2691

2692
2693
2694
2695
2696
2697
2698
....
2825
2826
2827
2828
2829
2830
2831
2832

2833
2834
2835
2836
2837
2838
2839
....
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901

2902
2903
2904
2905
2906









2907
2908
2909
2910
2911
2912
2913
....
3016
3017
3018
3019
3020
3021
3022



3023
3024
3025
3026
3027
3028
3029
....
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
....
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
....
4270
4271
4272
4273
4274
4275
4276









































































4277
4278
4279
4280
4281
4282
4283
....
4364
4365
4366
4367
4368
4369
4370

4371
4372
4373
4374
4375
4376
4377
....
4490
4491
4492
4493
4494
4495
4496









4497
4498
4499
4500
4501
4502
4503
....
4574
4575
4576
4577
4578
4579
4580

4581
4582
4583
4584
4585
4586
4587
4588
4589
4590

4591
4592
4593
4594
4595
4596
4597
....
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
....
4658
4659
4660
4661
4662
4663
4664




4665
4666
4667
4668
4669
4670
4671
#define WHERE_IDX_ONLY     0x00800000  /* Use index only - omit table */
#define WHERE_ORDERBY      0x01000000  /* Output will appear in correct order */
#define WHERE_REVERSE      0x02000000  /* Scan in reverse order */
#define WHERE_UNIQUE       0x04000000  /* Selects no more than one row */
#define WHERE_VIRTUALTABLE 0x08000000  /* Use virtual-table processing */
#define WHERE_MULTI_OR     0x10000000  /* OR using multiple indices */
#define WHERE_TEMP_INDEX   0x20000000  /* Uses an ephemeral index */


/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
................................................................................
){
  int i, j;                       /* Loop counters */
  int sortOrder = 0;              /* XOR of index and ORDER BY sort direction */
  int nTerm;                      /* Number of ORDER BY terms */
  struct ExprList_item *pTerm;    /* A term of the ORDER BY clause */
  sqlite3 *db = pParse->db;

  assert( pOrderBy!=0 );



  nTerm = pOrderBy->nExpr;
  assert( nTerm>0 );

  /* Argument pIdx must either point to a 'real' named index structure, 
  ** or an index structure allocated on the stack by bestBtreeIndex() to
  ** represent the rowid index that is part of every table.  */
  assert( pIdx->zName || (pIdx->nColumn==1 && pIdx->aiColumn[0]==-1) );
................................................................................
      ** to sort because the primary key is unique and so none of the other
      ** columns will make any difference
      */
      j = nTerm;
    }
  }

  *pbRev = sortOrder!=0;
  if( j>=nTerm ){
    /* All terms of the ORDER BY clause are covered by this index so
    ** this index can be used for sorting. */
    return 1;
  }
  if( pIdx->onError!=OE_None && i==pIdx->nColumn
      && (wsFlags & WHERE_COLUMN_NULL)==0
................................................................................
static void bestBtreeIndex(
  Parse *pParse,              /* The parsing context */
  WhereClause *pWC,           /* The WHERE clause */
  struct SrcList_item *pSrc,  /* The FROM clause term to search */
  Bitmask notReady,           /* Mask of cursors not available for indexing */
  Bitmask notValid,           /* Cursors not available for any purpose */
  ExprList *pOrderBy,         /* The ORDER BY clause */

  WhereCost *pCost            /* Lowest cost query plan */
){
  int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  Index *pProbe;              /* An index we are evaluating */
  Index *pIdx;                /* Copy of pProbe, or zero for IPK index */
  int eqTermMask;             /* Current mask of valid equality operators */
  int idxEqTermMask;          /* Index mask of valid equality operators */
................................................................................
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;                      /* Number of == or IN terms matching index */
    int bInEst = 0;               /* True if "x IN (SELECT...)" seen */
    int nInMul = 1;               /* Number of distinct equalities to lookup */
    int estBound = 100;           /* Estimated reduction in search space */
    int nBound = 0;               /* Number of range constraints seen */
    int bSort = 0;                /* True if external sort required */

    int bLookup = 0;              /* True if not a covering index */
    WhereTerm *pTerm;             /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT2
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif

    /* Determine the values of nEq and nInMul */
................................................................................
      }
    }

    /* If there is an ORDER BY clause and the index being considered will
    ** naturally scan rows in the required order, set the appropriate flags
    ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
    ** will scan rows in a different order, set the bSort variable.  */
    if( pOrderBy ){
      if( (wsFlags & WHERE_COLUMN_IN)==0
        && pProbe->bUnordered==0
        && isSortingIndex(pParse, pWC->pMaskSet, pProbe, iCur, pOrderBy,
                          nEq, wsFlags, &rev)
      ){

        wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
        wsFlags |= (rev ? WHERE_REVERSE : 0);
      }else{
        bSort = 1;
      }









    }

    /* If currently calculating the cost of using an index (not the IPK
    ** index), determine if all required column data may be obtained without 
    ** using the main table (i.e. if the index is a covering
    ** index for this query). If it is, set the WHERE_IDX_ONLY flag in
    ** wsFlags. Otherwise, set the bLookup variable to true.  */
................................................................................
    ** adds C*N*log10(N) to the cost, where N is the number of rows to be 
    ** sorted and C is a factor between 1.95 and 4.3.  We will split the
    ** difference and select C of 3.0.
    */
    if( bSort ){
      cost += nRow*estLog(nRow)*3;
    }




    /**** Cost of using this index has now been computed ****/

    /* If there are additional constraints on this table that cannot
    ** be used with the current index, but which might lower the number
    ** of output rows, adjust the nRow value accordingly.  This only 
    ** matters if the current index is the least costly, so do not bother
................................................................................
    if( p->needToFreeIdxStr ){
      sqlite3_free(p->idxStr);
    }
    sqlite3DbFree(pParse->db, p);
  }else
#endif
  {
    bestBtreeIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
  }
}

/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
** or USING clause of that join.
................................................................................
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);

    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){
        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */
        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrTerm->pExpr, 0,
                        WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY);
        if( pSubWInfo ){
          explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
................................................................................
      }
    }
    whereClauseClear(pWInfo->pWC);
    sqlite3DbFree(db, pWInfo);
  }
}











































































/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an opaque structure that contains
** information needed to terminate the loop.  Later, the calling routine
** should invoke sqlite3WhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
................................................................................
** output order, then the *ppOrderBy is unchanged.
*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */

  u16 wctrlFlags        /* One of the WHERE_* flags defined in sqliteInt.h */
){
  int i;                     /* Loop counter */
  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 */
................................................................................
  ** want to analyze these virtual terms, so start analyzing at the end
  ** and work forward so that the added virtual terms are never processed.
  */
  exprAnalyzeAll(pTabList, pWC);
  if( db->mallocFailed ){
    goto whereBeginError;
  }










  /* Chose the best index to use for each table in the FROM clause.
  **
  ** This loop fills in the following fields:
  **
  **   pWInfo->a[].pIdx      The index to use for this level of the loop.
  **   pWInfo->a[].wsFlags   WHERE_xxx flags associated with pIdx
................................................................................
    notIndexed = 0;
    for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){
      Bitmask mask;             /* Mask of tables not yet ready */
      for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){
        int doNotReorder;    /* True if this table should not be reordered */
        WhereCost sCost;     /* Cost information from best[Virtual]Index() */
        ExprList *pOrderBy;  /* ORDER BY clause for index to optimize */

  
        doNotReorder =  (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0;
        if( j!=iFrom && doNotReorder ) break;
        m = getMask(pMaskSet, pTabItem->iCursor);
        if( (m & notReady)==0 ){
          if( j==iFrom ) iFrom++;
          continue;
        }
        mask = (isOptimal ? m : notReady);
        pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0);

        if( pTabItem->pIndex==0 ) nUnconstrained++;
  
        WHERETRACE(("=== trying table %d with isOptimal=%d ===\n",
                    j, isOptimal));
        assert( pTabItem->pTab );
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(pTabItem->pTab) ){
................................................................................
          sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo;
          bestVirtualIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy,
                           &sCost, pp);
        }else 
#endif
        {
          bestBtreeIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy,
                         &sCost);
        }
        assert( isOptimal || (sCost.used&notReady)==0 );

        /* If an INDEXED BY clause is present, then the plan must use that
        ** index if it uses any index at all */
        assert( pTabItem->pIndex==0 
                  || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0
................................................................................
    assert( bestJ>=0 );
    assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d"
                " with cost=%g and nRow=%g\n",
                bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow));
    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
      *ppOrderBy = 0;




    }
    andFlags &= bestPlan.plan.wsFlags;
    pLevel->plan = bestPlan.plan;
    testcase( bestPlan.plan.wsFlags & WHERE_INDEXED );
    testcase( bestPlan.plan.wsFlags & WHERE_TEMP_INDEX );
    if( bestPlan.plan.wsFlags & (WHERE_INDEXED|WHERE_TEMP_INDEX) ){
      pLevel->iIdxCur = pParse->nTab++;







>







 







|
>
>
>







 







|







 







>







 







|
>







 







|
<
<
|
<
|
>
|
|
<
<
|
>
>
>
>
>
>
>
>
>







 







>
>
>







 







|







 







|







 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







 







>







 







>
>
>
>
>
>
>
>
>







 







>










>







 







|







 







>
>
>
>







249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
....
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
....
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
....
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
....
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
....
2895
2896
2897
2898
2899
2900
2901
2902


2903

2904
2905
2906
2907


2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
....
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
....
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
....
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
....
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
....
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
....
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
....
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
....
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
....
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
#define WHERE_IDX_ONLY     0x00800000  /* Use index only - omit table */
#define WHERE_ORDERBY      0x01000000  /* Output will appear in correct order */
#define WHERE_REVERSE      0x02000000  /* Scan in reverse order */
#define WHERE_UNIQUE       0x04000000  /* Selects no more than one row */
#define WHERE_VIRTUALTABLE 0x08000000  /* Use virtual-table processing */
#define WHERE_MULTI_OR     0x10000000  /* OR using multiple indices */
#define WHERE_TEMP_INDEX   0x20000000  /* Uses an ephemeral index */
#define WHERE_DISTINCT     0x40000000  /* Correct order for DISTINCT */

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
................................................................................
){
  int i, j;                       /* Loop counters */
  int sortOrder = 0;              /* XOR of index and ORDER BY sort direction */
  int nTerm;                      /* Number of ORDER BY terms */
  struct ExprList_item *pTerm;    /* A term of the ORDER BY clause */
  sqlite3 *db = pParse->db;

  if( !pOrderBy ) return 0;
  if( wsFlags & WHERE_COLUMN_IN ) return 0;
  if( pIdx->bUnordered ) return 0;

  nTerm = pOrderBy->nExpr;
  assert( nTerm>0 );

  /* Argument pIdx must either point to a 'real' named index structure, 
  ** or an index structure allocated on the stack by bestBtreeIndex() to
  ** represent the rowid index that is part of every table.  */
  assert( pIdx->zName || (pIdx->nColumn==1 && pIdx->aiColumn[0]==-1) );
................................................................................
      ** to sort because the primary key is unique and so none of the other
      ** columns will make any difference
      */
      j = nTerm;
    }
  }

  if( pbRev ) *pbRev = sortOrder!=0;
  if( j>=nTerm ){
    /* All terms of the ORDER BY clause are covered by this index so
    ** this index can be used for sorting. */
    return 1;
  }
  if( pIdx->onError!=OE_None && i==pIdx->nColumn
      && (wsFlags & WHERE_COLUMN_NULL)==0
................................................................................
static void bestBtreeIndex(
  Parse *pParse,              /* The parsing context */
  WhereClause *pWC,           /* The WHERE clause */
  struct SrcList_item *pSrc,  /* The FROM clause term to search */
  Bitmask notReady,           /* Mask of cursors not available for indexing */
  Bitmask notValid,           /* Cursors not available for any purpose */
  ExprList *pOrderBy,         /* The ORDER BY clause */
  ExprList *pDistinct,        /* The select-list if query is DISTINCT */
  WhereCost *pCost            /* Lowest cost query plan */
){
  int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  Index *pProbe;              /* An index we are evaluating */
  Index *pIdx;                /* Copy of pProbe, or zero for IPK index */
  int eqTermMask;             /* Current mask of valid equality operators */
  int idxEqTermMask;          /* Index mask of valid equality operators */
................................................................................
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;                      /* Number of == or IN terms matching index */
    int bInEst = 0;               /* True if "x IN (SELECT...)" seen */
    int nInMul = 1;               /* Number of distinct equalities to lookup */
    int estBound = 100;           /* Estimated reduction in search space */
    int nBound = 0;               /* Number of range constraints seen */
    int bSort = !!pOrderBy;       /* True if external sort required */
    int bDist = !!pDistinct;      /* True if index cannot help with DISTINCT */
    int bLookup = 0;              /* True if not a covering index */
    WhereTerm *pTerm;             /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT2
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif

    /* Determine the values of nEq and nInMul */
................................................................................
      }
    }

    /* If there is an ORDER BY clause and the index being considered will
    ** naturally scan rows in the required order, set the appropriate flags
    ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
    ** will scan rows in a different order, set the bSort variable.  */
    if( isSortingIndex(


          pParse, pWC->pMaskSet, pProbe, iCur, pOrderBy, nEq, wsFlags, &rev)

    ){
      bSort = 0;
      wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
      wsFlags |= (rev ? WHERE_REVERSE : 0);


    }

    /* If there is a DISTINCT qualifier and this index will scan rows in
    ** order of the DISTINCT expressions, clear bDist and set the appropriate
    ** flags in wsFlags. */
    if( isSortingIndex(
          pParse, pWC->pMaskSet, pProbe, iCur, pDistinct, nEq, wsFlags, 0)
    ){
      bDist = 0;
      wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_DISTINCT;
    }

    /* If currently calculating the cost of using an index (not the IPK
    ** index), determine if all required column data may be obtained without 
    ** using the main table (i.e. if the index is a covering
    ** index for this query). If it is, set the WHERE_IDX_ONLY flag in
    ** wsFlags. Otherwise, set the bLookup variable to true.  */
................................................................................
    ** adds C*N*log10(N) to the cost, where N is the number of rows to be 
    ** sorted and C is a factor between 1.95 and 4.3.  We will split the
    ** difference and select C of 3.0.
    */
    if( bSort ){
      cost += nRow*estLog(nRow)*3;
    }
    if( bDist ){
      cost += nRow*estLog(nRow)*3;
    }

    /**** Cost of using this index has now been computed ****/

    /* If there are additional constraints on this table that cannot
    ** be used with the current index, but which might lower the number
    ** of output rows, adjust the nRow value accordingly.  This only 
    ** matters if the current index is the least costly, so do not bother
................................................................................
    if( p->needToFreeIdxStr ){
      sqlite3_free(p->idxStr);
    }
    sqlite3DbFree(pParse->db, p);
  }else
#endif
  {
    bestBtreeIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, 0, pCost);
  }
}

/*
** Disable a term in the WHERE clause.  Except, do not disable the term
** if it controls a LEFT OUTER JOIN and it did not originate in the ON
** or USING clause of that join.
................................................................................
    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);

    for(ii=0; ii<pOrWc->nTerm; ii++){
      WhereTerm *pOrTerm = &pOrWc->a[ii];
      if( pOrTerm->leftCursor==iCur || pOrTerm->eOperator==WO_AND ){
        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */
        /* Loop through table entries that match term pOrTerm. */
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrTerm->pExpr, 0, 0,
                        WHERE_OMIT_OPEN | WHERE_OMIT_CLOSE |
                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY);
        if( pSubWInfo ){
          explainOneScan(
              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
          );
          if( (wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
................................................................................
      }
    }
    whereClauseClear(pWInfo->pWC);
    sqlite3DbFree(db, pWInfo);
  }
}

/*
** Return true if the DISTINCT expression-list passed as the third argument
** is redundant. A DISTINCT list is redundant if the database contains a
** UNIQUE index that guarantees that the result of the query will be distinct
** anyway.
*/
static int whereDistinctRedundant(
  Parse *pParse,
  SrcList *pTabList,
  WhereClause *pWC,
  ExprList *pDistinct
){
  Table *pTab;
  Index *pIdx;
  int i;
  int iBase;

  /* If there is more than one table or sub-select in the FROM clause of
  ** this query, then it will not be possible to show that the DISTINCT 
  ** clause is redundant. */
  if( pTabList->nSrc!=1 ) return 0;
  iBase = pTabList->a[0].iCursor;
  pTab = pTabList->a[0].pTab;

  /* Check if all the expressions in the ExprList are of type TK_COLUMN and
  ** on the same table. If this is not the case, return early, since it will 
  ** not be possible to prove that the DISTINCT qualifier is redundant. 
  ** If any of the expressions is an IPK column, then return true.
  */
  for(i=0; i<pDistinct->nExpr; i++){
    Expr *p = pDistinct->a[i].pExpr;
    if( p->op!=TK_COLUMN || p->iTable!=iBase ) return 0;
    if( p->iColumn<0 ) return 1;
  }

  /* Loop through all indices on the table, checking each to see if it makes
  ** the DISTINCT qualifier redundant. It does so if:
  **
  **   1. The index is itself UNIQUE, and
  **
  **   2. All of the columns in the index are either part of the pDistinct
  **      list, or else the WHERE clause contains a term of the form "col=X",
  **      where X is a constant value. The collation sequences of the
  **      comparison and select-list expressions must match those of the index.
  */
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    if( pIdx->onError==OE_None ) continue;
    for(i=0; i<pIdx->nColumn; i++){
      int iCol = pIdx->aiColumn[i];
      const char *zColl = pIdx->azColl[i];

      if( 0==findTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){
        int j;
        for(j=0; j<pDistinct->nExpr; j++){
          Expr *p = pDistinct->a[j].pExpr;
          if( p->iColumn==iCol ){
            CollSeq *pColl = sqlite3ExprCollSeq(pParse, p);
            const char *zEColl = (pColl ? pColl : pParse->db->pDfltColl)->zName;
            if( 0==sqlite3StrICmp(zColl, zEColl) ) break;
          }
        }
        if( j==pDistinct->nExpr ) break;
      }
    }
    if( i==pIdx->nColumn ){
      /* This index implies that the DISTINCT qualifier is redundant. */
      return 1;
    }
  }

  return 0;
}


/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an opaque structure that contains
** information needed to terminate the loop.  Later, the calling routine
** should invoke sqlite3WhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
................................................................................
** output order, then the *ppOrderBy is unchanged.
*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  ExprList **ppOrderBy, /* 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 i;                     /* Loop counter */
  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 */
................................................................................
  ** want to analyze these virtual terms, so start analyzing at the end
  ** and work forward so that the added virtual terms are never processed.
  */
  exprAnalyzeAll(pTabList, pWC);
  if( db->mallocFailed ){
    goto whereBeginError;
  }

  /* 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 && whereDistinctRedundant(pParse, pTabList, pWC, pDistinct) ){
    pDistinct = 0;
    pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
  }

  /* Chose the best index to use for each table in the FROM clause.
  **
  ** This loop fills in the following fields:
  **
  **   pWInfo->a[].pIdx      The index to use for this level of the loop.
  **   pWInfo->a[].wsFlags   WHERE_xxx flags associated with pIdx
................................................................................
    notIndexed = 0;
    for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){
      Bitmask mask;             /* Mask of tables not yet ready */
      for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){
        int doNotReorder;    /* True if this table should not be reordered */
        WhereCost sCost;     /* Cost information from best[Virtual]Index() */
        ExprList *pOrderBy;  /* ORDER BY clause for index to optimize */
        ExprList *pDist;     /* DISTINCT clause for index to optimize */
  
        doNotReorder =  (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0;
        if( j!=iFrom && doNotReorder ) break;
        m = getMask(pMaskSet, pTabItem->iCursor);
        if( (m & notReady)==0 ){
          if( j==iFrom ) iFrom++;
          continue;
        }
        mask = (isOptimal ? m : notReady);
        pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0);
        pDist = (i==0 ? pDistinct : 0);
        if( pTabItem->pIndex==0 ) nUnconstrained++;
  
        WHERETRACE(("=== trying table %d with isOptimal=%d ===\n",
                    j, isOptimal));
        assert( pTabItem->pTab );
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(pTabItem->pTab) ){
................................................................................
          sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo;
          bestVirtualIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy,
                           &sCost, pp);
        }else 
#endif
        {
          bestBtreeIndex(pParse, pWC, pTabItem, mask, notReady, pOrderBy,
              pDist, &sCost);
        }
        assert( isOptimal || (sCost.used&notReady)==0 );

        /* If an INDEXED BY clause is present, then the plan must use that
        ** index if it uses any index at all */
        assert( pTabItem->pIndex==0 
                  || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0
................................................................................
    assert( bestJ>=0 );
    assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d"
                " with cost=%g and nRow=%g\n",
                bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow));
    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
      *ppOrderBy = 0;
    }
    if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
      assert( pWInfo->eDistinct==0 );
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
    andFlags &= bestPlan.plan.wsFlags;
    pLevel->plan = bestPlan.plan;
    testcase( bestPlan.plan.wsFlags & WHERE_INDEXED );
    testcase( bestPlan.plan.wsFlags & WHERE_TEMP_INDEX );
    if( bestPlan.plan.wsFlags & (WHERE_INDEXED|WHERE_TEMP_INDEX) ){
      pLevel->iIdxCur = pParse->nTab++;

Changes to test/collate5.test.

53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
    INSERT INTO collate5t1 VALUES('N', NULL);
  } 
} {}
do_test collate5-1.1 {
  execsql {
    SELECT DISTINCT a FROM collate5t1;
  }
} {A B N}
do_test collate5-1.2 {
  execsql {
    SELECT DISTINCT b FROM collate5t1;
  }
} {{} Apple apple banana}
do_test collate5-1.3 {
  execsql {
    SELECT DISTINCT a, b FROM collate5t1;
  }
} {A Apple a apple B banana N {}}

# Ticket #3376
#
do_test collate5-1.11 {
  execsql {
    CREATE TABLE tkt3376(a COLLATE nocase PRIMARY KEY);
    INSERT INTO tkt3376 VALUES('abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz');







|




|




|







53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
    INSERT INTO collate5t1 VALUES('N', NULL);
  } 
} {}
do_test collate5-1.1 {
  execsql {
    SELECT DISTINCT a FROM collate5t1;
  }
} {a b n}
do_test collate5-1.2 {
  execsql {
    SELECT DISTINCT b FROM collate5t1;
  }
} {apple Apple banana {}}
do_test collate5-1.3 {
  execsql {
    SELECT DISTINCT a, b FROM collate5t1;
  }
} {a apple A Apple b banana n {}}

# Ticket #3376
#
do_test collate5-1.11 {
  execsql {
    CREATE TABLE tkt3376(a COLLATE nocase PRIMARY KEY);
    INSERT INTO tkt3376 VALUES('abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz');

Changes to test/e_select.test.

1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
do_select_tests e_select-5 {
  3.1 "SELECT ALL x FROM h2" {One Two Three Four one two three four}
  3.2 "SELECT ALL x FROM h1, h2 ON (x=b)" {One one Four four}

  3.1 "SELECT x FROM h2" {One Two Three Four one two three four}
  3.2 "SELECT x FROM h1, h2 ON (x=b)" {One one Four four}

  4.1 "SELECT DISTINCT x FROM h2" {four one three two}
  4.2 "SELECT DISTINCT x FROM h1, h2 ON (x=b)" {four one}
} 

# EVIDENCE-OF: R-02054-15343 For the purposes of detecting duplicate
# rows, two NULL values are considered to be equal.
#
do_select_tests e_select-5.5 {
  1  "SELECT DISTINCT d FROM h3" {{} 2 2,3 2,4 3}
}

# EVIDENCE-OF: R-58359-52112 The normal rules for selecting a collation
# sequence to compare text values with apply.
#
do_select_tests e_select-5.6 {
  1  "SELECT DISTINCT b FROM h1"                  {I IV four i iv one}
  2  "SELECT DISTINCT b COLLATE nocase FROM h1"   {four i iv one}
  3  "SELECT DISTINCT x FROM h2"                  {four one three two}
  4  "SELECT DISTINCT x COLLATE binary FROM h2"   {
    Four One Three Two four one three two
  }
}

#-------------------------------------------------------------------------
# The following tests - e_select-7.* - test that statements made to do
# with compound SELECT statements are correct.
#







|
|













|
|
|

|







1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
do_select_tests e_select-5 {
  3.1 "SELECT ALL x FROM h2" {One Two Three Four one two three four}
  3.2 "SELECT ALL x FROM h1, h2 ON (x=b)" {One one Four four}

  3.1 "SELECT x FROM h2" {One Two Three Four one two three four}
  3.2 "SELECT x FROM h1, h2 ON (x=b)" {One one Four four}

  4.1 "SELECT DISTINCT x FROM h2" {One Two Three Four}
  4.2 "SELECT DISTINCT x FROM h1, h2 ON (x=b)" {One Four}
} 

# EVIDENCE-OF: R-02054-15343 For the purposes of detecting duplicate
# rows, two NULL values are considered to be equal.
#
do_select_tests e_select-5.5 {
  1  "SELECT DISTINCT d FROM h3" {{} 2 2,3 2,4 3}
}

# EVIDENCE-OF: R-58359-52112 The normal rules for selecting a collation
# sequence to compare text values with apply.
#
do_select_tests e_select-5.6 {
  1  "SELECT DISTINCT b FROM h1"                  {one I i four IV iv}
  2  "SELECT DISTINCT b COLLATE nocase FROM h1"   {one I four IV}
  3  "SELECT DISTINCT x FROM h2"                  {One Two Three Four}
  4  "SELECT DISTINCT x COLLATE binary FROM h2"   {
    One Two Three Four one two three four
  }
}

#-------------------------------------------------------------------------
# The following tests - e_select-7.* - test that statements made to do
# with compound SELECT statements are correct.
#

Changes to test/fuzzer1.test.

1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
do_test fuzzer1-2.3 {
  execsql {
    SELECT DISTINCT streetname.n FROM f2, streetname
     WHERE f2.word MATCH 'tayle'
       AND f2.distance<=200
       AND streetname.n>=f2.word AND streetname.n<=(f2.word || x'F7BFBFBF')
  }
} {steelewood tallia tallu talwyn taymouth thelema trailer {tyler finley}}


finish_test







|



1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
do_test fuzzer1-2.3 {
  execsql {
    SELECT DISTINCT streetname.n FROM f2, streetname
     WHERE f2.word MATCH 'tayle'
       AND f2.distance<=200
       AND streetname.n>=f2.word AND streetname.n<=(f2.word || x'F7BFBFBF')
  }
} {{tyler finley} trailer taymouth steelewood tallia tallu talwyn thelema}


finish_test

Changes to test/insert4.test.

108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
#
do_test insert4-2.4.1 {
  execsql {
    DELETE FROM t3;
    INSERT INTO t3 SELECT DISTINCT * FROM t2;
    SELECT * FROM t3;
  }
} {1 9 9 1}
xferopt_test insert4-2.4.2 0
do_test insert4-2.4.3 {
  catchsql {
    DELETE FROM t1;
    INSERT INTO t1 SELECT DISTINCT * FROM t2;
  }
} {1 {constraint failed}}







|







108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
#
do_test insert4-2.4.1 {
  execsql {
    DELETE FROM t3;
    INSERT INTO t3 SELECT DISTINCT * FROM t2;
    SELECT * FROM t3;
  }
} {9 1 1 9}
xferopt_test insert4-2.4.2 0
do_test insert4-2.4.3 {
  catchsql {
    DELETE FROM t1;
    INSERT INTO t1 SELECT DISTINCT * FROM t2;
  }
} {1 {constraint failed}}

Changes to test/misc5.test.

501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
          )    
          WHERE artist <> '' 
        )  
       )       
      )  
      ORDER BY LOWER(artist) ASC;
    }
  } {one}
}

# Ticket #1370.  Do not overwrite small files (less than 1024 bytes)
# when trying to open them as a database.
#
if {[permutation] == ""} {
  do_test misc5-4.1 {







|







501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
          )    
          WHERE artist <> '' 
        )  
       )       
      )  
      ORDER BY LOWER(artist) ASC;
    }
  } {two}
}

# Ticket #1370.  Do not overwrite small files (less than 1024 bytes)
# when trying to open them as a database.
#
if {[permutation] == ""} {
  do_test misc5-4.1 {

Changes to test/selectB.test.

351
352
353
354
355
356
357
358
359
360
361
362
363
364
365

  do_test selectB-$ii.19 {
    execsql {
      SELECT * FROM (
        SELECT DISTINCT (a/10) FROM t1 UNION ALL SELECT DISTINCT(d%2) FROM t2
      )
    }
  } {0 1 0 1}

  do_test selectB-$ii.20 {
    execsql {
      SELECT DISTINCT * FROM (
        SELECT DISTINCT (a/10) FROM t1 UNION ALL SELECT DISTINCT(d%2) FROM t2
      )
    }







|







351
352
353
354
355
356
357
358
359
360
361
362
363
364
365

  do_test selectB-$ii.19 {
    execsql {
      SELECT * FROM (
        SELECT DISTINCT (a/10) FROM t1 UNION ALL SELECT DISTINCT(d%2) FROM t2
      )
    }
  } {0 1 1 0}

  do_test selectB-$ii.20 {
    execsql {
      SELECT DISTINCT * FROM (
        SELECT DISTINCT (a/10) FROM t1 UNION ALL SELECT DISTINCT(d%2) FROM t2
      )
    }