/ Check-in [1e874629]
Login

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

Overview
Comment:Query planner enhancements to be more agressive about optimizing out ORDER BY clauses - in particular the query planner now has the ability to omit ORDER BY clauses that span multiple tables in a join.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 1e874629d7cf568368b912b295bd3001147d0b52
User & Date: drh 2012-09-28 00:44:28
References
2013-06-03
13:23 New ticket [bc1aea7b] Incorrect result on LEFT JOIN with OR constraints and an ORDER BY clause. artifact: a92b978f user: drh
2013-04-22
18:16 New ticket [ba82a4a4] Query optimizer removes ORDER BY when it is needed. artifact: 39396502 user: drh
Context
2012-09-28
18:13
Modify the clearCell function to use SQLITE_CORRUPT_BKPT in the one place it was not. check-in: 472beb30 user: mistachkin tags: trunk
13:05
Merge the latest trunk changes (especially "PRAGMA busy_timeout" and the ORDER BY query planner optimizations) into the sessions branch. check-in: 6ca8eae1 user: drh tags: sessions
10:57
Merge the latest trunk changes (PRAGMA busy_timeout and the ORDER BY query planner enhancements) into the apple-osx branch. check-in: 6a5c59dd user: drh tags: apple-osx
00:44
Query planner enhancements to be more agressive about optimizing out ORDER BY clauses - in particular the query planner now has the ability to omit ORDER BY clauses that span multiple tables in a join. check-in: 1e874629 user: drh tags: trunk
2012-09-27
23:27
Fix some corner case behavior in the new ORDER BY optimization logic. Remove the SQLITE_OrderByIdx bit from the SQLITE_TESTCTRL_OPTIMIZATIONS mask, since enabling it caused many TH3 tests to fail when the NO_OPT configuration parameter was engaged, and since there really isn't any need to turn that optimization off. The SQLITE_OrderByIdxJoin bit remains. Closed-Leaf check-in: 98b63371 user: drh tags: qp-enhancements
21:03
Modify generation of resource header file for MSVC so that it can work from outside the working directory. check-in: 20caf80c user: mistachkin tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/delete.c.

634
635
636
637
638
639
640
641


642
643
644
645
646
647
648
649
650
651
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx, -1);
    }
  }
  if( doMakeRec ){
    const char *zAff;
    if( pTab->pSelect || (pParse->db->flags & SQLITE_IdxRealAsInt)!=0 ){


      zAff = 0;
    }else{
      zAff = sqlite3IndexAffinityStr(v, pIdx);
    }
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
    sqlite3VdbeChangeP4(v, -1, zAff, P4_TRANSIENT);
  }
  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}







|
>
>










634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx, -1);
    }
  }
  if( doMakeRec ){
    const char *zAff;
    if( pTab->pSelect
     || OptimizationDisabled(pParse->db, SQLITE_IdxRealAsInt)
    ){
      zAff = 0;
    }else{
      zAff = sqlite3IndexAffinityStr(v, pIdx);
    }
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
    sqlite3VdbeChangeP4(v, -1, zAff, P4_TRANSIENT);
  }
  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}

Changes to src/expr.c.

2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
....
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
  assert( iReg>0 );  /* Register numbers are always positive */
  assert( iCol>=-1 && iCol<32768 );  /* Finite column numbers */

  /* The SQLITE_ColumnCache flag disables the column cache.  This is used
  ** for testing only - to verify that SQLite always gets the same answer
  ** with and without the column cache.
  */
  if( pParse->db->flags & SQLITE_ColumnCache ) return;

  /* First replace any existing entry.
  **
  ** Actually, the way the column cache is currently used, we are guaranteed
  ** that the object will never already be in cache.  Verify this guarantee.
  */
#ifndef NDEBUG
................................................................................
** interface.  This allows test logic to verify that the same answer is
** obtained for queries regardless of whether or not constants are
** precomputed into registers or if they are inserted in-line.
*/
void sqlite3ExprCodeConstants(Parse *pParse, Expr *pExpr){
  Walker w;
  if( pParse->cookieGoto ) return;
  if( (pParse->db->flags & SQLITE_FactorOutConst)!=0 ) return;
  w.xExprCallback = evalConstExpr;
  w.xSelectCallback = 0;
  w.pParse = pParse;
  sqlite3WalkExpr(&w, pExpr);
}









|







 







|







2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
....
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
  assert( iReg>0 );  /* Register numbers are always positive */
  assert( iCol>=-1 && iCol<32768 );  /* Finite column numbers */

  /* The SQLITE_ColumnCache flag disables the column cache.  This is used
  ** for testing only - to verify that SQLite always gets the same answer
  ** with and without the column cache.
  */
  if( OptimizationDisabled(pParse->db, SQLITE_ColumnCache) ) return;

  /* First replace any existing entry.
  **
  ** Actually, the way the column cache is currently used, we are guaranteed
  ** that the object will never already be in cache.  Verify this guarantee.
  */
#ifndef NDEBUG
................................................................................
** interface.  This allows test logic to verify that the same answer is
** obtained for queries regardless of whether or not constants are
** precomputed into registers or if they are inserted in-line.
*/
void sqlite3ExprCodeConstants(Parse *pParse, Expr *pExpr){
  Walker w;
  if( pParse->cookieGoto ) return;
  if( OptimizationDisabled(pParse->db, SQLITE_FactorOutConst) ) return;
  w.xExprCallback = evalConstExpr;
  w.xSelectCallback = 0;
  w.pParse = pParse;
  sqlite3WalkExpr(&w, pExpr);
}


Changes to src/main.c.

3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
    ** operation N should be 0.  The idea is that a test program (like the
    ** SQL Logic Test or SLT test module) can run the same SQL multiple times
    ** with various optimizations disabled to verify that the same answer
    ** is obtained in every case.
    */
    case SQLITE_TESTCTRL_OPTIMIZATIONS: {
      sqlite3 *db = va_arg(ap, sqlite3*);
      int x = va_arg(ap,int);
      db->flags = (x & SQLITE_OptMask) | (db->flags & ~SQLITE_OptMask);
      break;
    }

#ifdef SQLITE_N_KEYWORD
    /* sqlite3_test_control(SQLITE_TESTCTRL_ISKEYWORD, const char *zWord)
    **
    ** If zWord is a keyword recognized by the parser, then return the







|
<







3015
3016
3017
3018
3019
3020
3021
3022

3023
3024
3025
3026
3027
3028
3029
    ** operation N should be 0.  The idea is that a test program (like the
    ** SQL Logic Test or SLT test module) can run the same SQL multiple times
    ** with various optimizations disabled to verify that the same answer
    ** is obtained in every case.
    */
    case SQLITE_TESTCTRL_OPTIMIZATIONS: {
      sqlite3 *db = va_arg(ap, sqlite3*);
      db->dbOptFlags = (u16)(va_arg(ap, int) & 0xffff);

      break;
    }

#ifdef SQLITE_N_KEYWORD
    /* sqlite3_test_control(SQLITE_TESTCTRL_ISKEYWORD, const char *zWord)
    **
    ** If zWord is a keyword recognized by the parser, then return the

Changes to src/select.c.

2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
....
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
....
4502
4503
4504
4505
4506
4507
4508

4509
4510
4511
4512
4513
4514
4515
  struct SrcList_item *pSubitem;   /* The subquery */
  sqlite3 *db = pParse->db;

  /* Check to see if flattening is permitted.  Return 0 if not.
  */
  assert( p!=0 );
  assert( p->pPrior==0 );  /* Unable to flatten compound queries */
  if( db->flags & SQLITE_QueryFlattener ) return 0;
  pSrc = p->pSrc;
  assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
  pSubitem = &pSrc->a[iFrom];
  iParent = pSubitem->iCursor;
  pSub = pSubitem->pSelect;
  assert( pSub!=0 );
  if( isAgg && subqueryIsAgg ) return 0;                 /* Restriction (1)  */
................................................................................
  ** 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.
  */
  if( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0
         && (db->flags & SQLITE_GroupByOrder)==0 ){
    pOrderBy = 0;
  }

  /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and 
  ** if the select-list is the same as the ORDER BY list, then this query
  ** can be rewritten as a GROUP BY. In other words, this:
  **
................................................................................
        resetAccumulator(pParse, &sAggInfo);
        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0);
        if( pWInfo==0 ){
          sqlite3ExprListDelete(db, pDel);
          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);

        if( pWInfo->nOBSat>0 ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
          VdbeComment((v, "%s() by index",
                (flag==WHERE_ORDERBY_MIN?"min":"max")));
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);







|







 







|







 







>







2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
....
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
....
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
  struct SrcList_item *pSubitem;   /* The subquery */
  sqlite3 *db = pParse->db;

  /* Check to see if flattening is permitted.  Return 0 if not.
  */
  assert( p!=0 );
  assert( p->pPrior==0 );  /* Unable to flatten compound queries */
  if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0;
  pSrc = p->pSrc;
  assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
  pSubitem = &pSrc->a[iFrom];
  iParent = pSubitem->iCursor;
  pSub = pSubitem->pSelect;
  assert( pSub!=0 );
  if( isAgg && subqueryIsAgg ) return 0;                 /* Restriction (1)  */
................................................................................
  ** 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.
  */
  if( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0
         && OptimizationEnabled(db, SQLITE_GroupByOrder) ){
    pOrderBy = 0;
  }

  /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and 
  ** if the select-list is the same as the ORDER BY list, then this query
  ** can be rewritten as a GROUP BY. In other words, this:
  **
................................................................................
        resetAccumulator(pParse, &sAggInfo);
        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0);
        if( pWInfo==0 ){
          sqlite3ExprListDelete(db, pDel);
          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);
        assert( pMinMax==0 || pMinMax->nExpr==1 );
        if( pWInfo->nOBSat>0 ){
          sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
          VdbeComment((v, "%s() by index",
                (flag==WHERE_ORDERBY_MIN?"min":"max")));
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);

Changes to src/sqliteInt.h.

823
824
825
826
827
828
829

830
831
832
833
834
835
836
...
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973












974
975
976
977
978
979
980
....
1902
1903
1904
1905
1906
1907
1908
1909

1910
1911
1912
1913
1914
1915
1916
  Db *aDb;                      /* All backends */
  int nDb;                      /* Number of backends currently in use */
  int flags;                    /* Miscellaneous flags. See below */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
  int errCode;                  /* Most recent error code (SQLITE_*) */
  int errMask;                  /* & result codes with this before returning */

  u8 autoCommit;                /* The auto-commit flag. */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  u8 mallocFailed;              /* True if we have seen a malloc failure */
  u8 dfltLockMode;              /* Default locking-mode for attached dbs */
  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
  u8 suppressErr;               /* Do not issue error messages if true */
  u8 vtabOnConflict;            /* Value to return for s3_vtab_on_conflict() */
................................................................................
** A macro to discover the encoding of a database.
*/
#define ENC(db) ((db)->aDb[0].pSchema->enc)

/*
** Possible values for the sqlite3.flags.
*/
#define SQLITE_VdbeTrace      0x00000100  /* True to trace VDBE execution */
#define SQLITE_InternChanges  0x00000200  /* Uncommitted Hash table changes */
#define SQLITE_FullColNames   0x00000400  /* Show full column names on SELECT */
#define SQLITE_ShortColNames  0x00000800  /* Show short columns names */
#define SQLITE_CountRows      0x00001000  /* Count rows changed by INSERT, */
                                          /*   DELETE, or UPDATE and return */
                                          /*   the count using a callback. */
#define SQLITE_NullCallback   0x00002000  /* Invoke the callback once if the */
                                          /*   result set is empty */
#define SQLITE_SqlTrace       0x00004000  /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    0x00008000  /* Debug listings of VDBE programs */
#define SQLITE_WriteSchema    0x00010000  /* OK to update SQLITE_MASTER */
                         /*   0x00020000  Unused */
#define SQLITE_IgnoreChecks   0x00040000  /* Do not enforce check constraints */
#define SQLITE_ReadUncommitted 0x0080000  /* For shared-cache mode */
#define SQLITE_LegacyFileFmt  0x00100000  /* Create new databases in format 1 */
#define SQLITE_FullFSync      0x00200000  /* Use full fsync on the backend */
#define SQLITE_CkptFullFSync  0x00400000  /* Use full fsync for checkpoint */
#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x08000000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x10000000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x20000000  /* Enable load_extension */
#define SQLITE_EnableTrigger  0x40000000  /* True to enable triggers */

/*
** Bits of the sqlite3.flags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
** These must be the low-order bits of the flags field.
*/
#define SQLITE_QueryFlattener 0x01   /* Disable query flattening */
#define SQLITE_ColumnCache    0x02   /* Disable the column cache */
#define SQLITE_GroupByOrder   0x04   /* Disable GROUPBY cover of ORDERBY */
#define SQLITE_FactorOutConst 0x08   /* Disable factoring out constants */
#define SQLITE_IdxRealAsInt   0x10   /* Store REAL as INT in indices */
#define SQLITE_DistinctOpt    0x20   /* DISTINCT using indexes */
#define SQLITE_CoverIdxScan   0x40   /* Disable covering index scans */
#define SQLITE_OptMask        0xff   /* Mask of all disablable opts */













/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
................................................................................
** Within the union, pIdx is only used when wsFlags&WHERE_INDEXED is true.
** pTerm is only used when wsFlags&WHERE_MULTI_OR is true.  And pVtabIdx
** is only used when wsFlags&WHERE_VIRTUALTABLE is true.  It is never the
** case that more than one of these conditions is true.
*/
struct WherePlan {
  u32 wsFlags;                   /* WHERE_* flags that describe the strategy */
  u32 nEq;                       /* Number of == constraints */

  double nRow;                   /* Estimated number of rows (for EQP) */
  union {
    Index *pIdx;                   /* Index when WHERE_INDEXED is true */
    struct WhereTerm *pTerm;       /* WHERE clause term for OR-search */
    sqlite3_index_info *pVtabIdx;  /* Virtual table index to use */
  } u;
};







>







 







|
|
|
|
|


|

|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|


|
|
|

|
|
|
|
|
|
|
|
>
>
>
>
>
>
>
>
>
>
>
>







 







|
>







823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
...
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
....
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
  Db *aDb;                      /* All backends */
  int nDb;                      /* Number of backends currently in use */
  int flags;                    /* Miscellaneous flags. See below */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  unsigned int openFlags;       /* Flags passed to sqlite3_vfs.xOpen() */
  int errCode;                  /* Most recent error code (SQLITE_*) */
  int errMask;                  /* & result codes with this before returning */
  u8 dbOptFlags;                /* Flags to enable/disable optimizations */
  u8 autoCommit;                /* The auto-commit flag. */
  u8 temp_store;                /* 1: file 2: memory 0: default */
  u8 mallocFailed;              /* True if we have seen a malloc failure */
  u8 dfltLockMode;              /* Default locking-mode for attached dbs */
  signed char nextAutovac;      /* Autovac setting after VACUUM if >=0 */
  u8 suppressErr;               /* Do not issue error messages if true */
  u8 vtabOnConflict;            /* Value to return for s3_vtab_on_conflict() */
................................................................................
** A macro to discover the encoding of a database.
*/
#define ENC(db) ((db)->aDb[0].pSchema->enc)

/*
** Possible values for the sqlite3.flags.
*/
#define SQLITE_VdbeTrace      0x00000001  /* True to trace VDBE execution */
#define SQLITE_InternChanges  0x00000002  /* Uncommitted Hash table changes */
#define SQLITE_FullColNames   0x00000004  /* Show full column names on SELECT */
#define SQLITE_ShortColNames  0x00000008  /* Show short columns names */
#define SQLITE_CountRows      0x00000010  /* Count rows changed by INSERT, */
                                          /*   DELETE, or UPDATE and return */
                                          /*   the count using a callback. */
#define SQLITE_NullCallback   0x00000020  /* Invoke the callback once if the */
                                          /*   result set is empty */
#define SQLITE_SqlTrace       0x00000040  /* Debug print SQL as it executes */
#define SQLITE_VdbeListing    0x00000080  /* Debug listings of VDBE programs */
#define SQLITE_WriteSchema    0x00000100  /* OK to update SQLITE_MASTER */
                         /*   0x00000200  Unused */
#define SQLITE_IgnoreChecks   0x00000400  /* Do not enforce check constraints */
#define SQLITE_ReadUncommitted 0x0000800  /* For shared-cache mode */
#define SQLITE_LegacyFileFmt  0x00001000  /* Create new databases in format 1 */
#define SQLITE_FullFSync      0x00002000  /* Use full fsync on the backend */
#define SQLITE_CkptFullFSync  0x00004000  /* Use full fsync for checkpoint */
#define SQLITE_RecoveryMode   0x00008000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x00010000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x00020000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x00040000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x00080000  /* Enable automatic indexes */
#define SQLITE_PreferBuiltin  0x00100000  /* Preference to built-in funcs */
#define SQLITE_LoadExtension  0x00200000  /* Enable load_extension */
#define SQLITE_EnableTrigger  0x00400000  /* True to enable triggers */

/*
** Bits of the sqlite3.dbOptFlags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface to
** selectively disable various optimizations.
*/
#define SQLITE_QueryFlattener 0x0001   /* Query flattening */
#define SQLITE_ColumnCache    0x0002   /* Column cache */
#define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
#define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
#define SQLITE_IdxRealAsInt   0x0010   /* Store REAL as INT in indices */
#define SQLITE_DistinctOpt    0x0020   /* DISTINCT using indexes */
#define SQLITE_CoverIdxScan   0x0040   /* Covering index scans */
#define SQLITE_OrderByIdxJoin 0x0080   /* ORDER BY of joins via index */
#define SQLITE_AllOpts        0x00ff   /* All optimizations */

/*
** Macros for testing whether or not optimizations are enabled or disabled.
*/
#ifndef SQLITE_OMIT_BUILTIN_TEST
#define OptimizationDisabled(db, mask)  (((db)->dbOptFlags&(mask))!=0)
#define OptimizationEnabled(db, mask)   (((db)->dbOptFlags&(mask))==0)
#else
#define OptimizationDisabled(db, mask)  0
#define OptimizationEnabled(db, mask)   1
#endif

/*
** Possible values for the sqlite.magic field.
** The numbers are obtained at random and have no special meaning, other
** than being distinct from one another.
*/
#define SQLITE_MAGIC_OPEN     0xa029a697  /* Database is open */
................................................................................
** Within the union, pIdx is only used when wsFlags&WHERE_INDEXED is true.
** pTerm is only used when wsFlags&WHERE_MULTI_OR is true.  And pVtabIdx
** is only used when wsFlags&WHERE_VIRTUALTABLE is true.  It is never the
** case that more than one of these conditions is true.
*/
struct WherePlan {
  u32 wsFlags;                   /* WHERE_* flags that describe the strategy */
  u16 nEq;                       /* Number of == constraints */
  u16 nOBSat;                    /* Number of ORDER BY terms satisfied */
  double nRow;                   /* Estimated number of rows (for EQP) */
  union {
    Index *pIdx;                   /* Index when WHERE_INDEXED is true */
    struct WhereTerm *pTerm;       /* WHERE clause term for OR-search */
    sqlite3_index_info *pVtabIdx;  /* Virtual table index to use */
  } u;
};

Changes to src/test1.c.

5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943

5944
5945
5946
5947
5948
5949
5950
  const char *zOpt;
  int onoff;
  int mask = 0;
  static const struct {
    const char *zOptName;
    int mask;
  } aOpt[] = {
    { "all",              SQLITE_OptMask        },
    { "query-flattener",  SQLITE_QueryFlattener },
    { "column-cache",     SQLITE_ColumnCache    },
    { "groupby-order",    SQLITE_GroupByOrder   },
    { "factor-constants", SQLITE_FactorOutConst },
    { "real-as-int",      SQLITE_IdxRealAsInt   },
    { "distinct-opt",     SQLITE_DistinctOpt    },
    { "cover-idx-scan",   SQLITE_CoverIdxScan   },

  };

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB OPT BOOLEAN");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;







|







>







5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
  const char *zOpt;
  int onoff;
  int mask = 0;
  static const struct {
    const char *zOptName;
    int mask;
  } aOpt[] = {
    { "all",              SQLITE_AllOpts        },
    { "query-flattener",  SQLITE_QueryFlattener },
    { "column-cache",     SQLITE_ColumnCache    },
    { "groupby-order",    SQLITE_GroupByOrder   },
    { "factor-constants", SQLITE_FactorOutConst },
    { "real-as-int",      SQLITE_IdxRealAsInt   },
    { "distinct-opt",     SQLITE_DistinctOpt    },
    { "cover-idx-scan",   SQLITE_CoverIdxScan   },
    { "order-by-idx-join",SQLITE_OrderByIdxJoin },
  };

  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB OPT BOOLEAN");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;

Changes to src/where.c.

263
264
265
266
267
268
269






















270
271
272
273
274
275
276
....
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420

1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
....
1586
1587
1588
1589
1590
1591
1592
1593
1594

1595
1596
1597
1598

1599
1600
1601




1602
1603
1604
1605
1606
1607
1608

1609
1610
1611
1612
1613
1614
1615
1616
1617

1618
1619

1620
1621
1622
1623


1624



1625











1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
....
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
....
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725





1726
1727



1728
1729





1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
....
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834


1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861

1862




1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880

1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
....
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
....
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
....
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
....
2194
2195
2196
2197
2198
2199
2200
2201

2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
....
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
....
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
....
2857
2858
2859
2860
2861
2862
2863
























2864























2865



























2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
....
2886
2887
2888
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
2914
2915
2916
2917
2918
2919
2920
2921
2922
....
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
....
2994
2995
2996
2997
2998
2999
3000




3001
3002
3003
3004
3005
3006
3007
....
3012
3013
3014
3015
3016
3017
3018




3019
3020
3021
3022
3023
3024
3025
....
3028
3029
3030
3031
3032
3033
3034

3035
3036
3037
3038
3039
3040
3041


3042
3043
3044
3045
3046




3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
....
3060
3061
3062
3063
3064
3065
3066



3067
3068
3069
3070
3071
3072
3073
....
3084
3085
3086
3087
3088
3089
3090
3091

3092
3093
3094
3095
3096
3097
3098
3099
3100
....
3108
3109
3110
3111
3112
3113
3114





3115
3116
3117


3118
3119
3120


3121
3122
3123
3124
3125

3126
3127
3128
3129
3130
3131
3132
3133
....
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
....
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
....
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
....
3323
3324
3325
3326
3327
3328
3329

3330
3331

3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347

3348
3349
3350
3351
3352
3353
3354
3355
....
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
....
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408

3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
....
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702

4703
4704
4705
4706
4707
4708

4709
4710





4711
4712
4713
4714
4715
4716
4717
....
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753

4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
....
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
....
4843
4844
4845
4846
4847
4848
4849
4850



4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
....
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
....
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923

4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961

4962
4963
4964
4965
4966
4967
4968
....
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990

4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001

5002
5003
5004
5005
5006
5007
5008
....
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
....
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079

5080
5081
5082
5083
5084
5085
5086
....
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156


5157
5158
5159
5160
5161
5162
5163
5164
#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 */
#define WHERE_COVER_SCAN   0x80000000  /* Full scan of a covering index */























/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
  WhereMaskSet *pMaskSet,  /* Mapping from table cursor numbers to bitmasks */
................................................................................
  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

/*
** Return TRUE if any of the expressions in pList->a[iFirst...] contain
** a reference to any table other than the iBase table.
*/
static int referencesOtherTables(
  ExprList *pList,          /* Search expressions in ths list */
  WhereMaskSet *pMaskSet,   /* Mapping from tables to bitmaps */
  int iFirst,               /* Be searching with the iFirst-th expression */
  int iBase                 /* Ignore references to this table */
){

  Bitmask allowed = ~getMask(pMaskSet, iBase);
  while( iFirst<pList->nExpr ){
    if( (exprTableUsage(pMaskSet, pList->a[iFirst++].pExpr)&allowed)!=0 ){
      return 1;
    }
  }
  return 0;
}

/*
** This function searches the expression list passed as the second argument
** for an expression of type TK_COLUMN that refers to the same column and
** uses the same collation sequence as the iCol'th column of index pIdx.
** Argument iBase is the cursor number used for the table that pIdx refers
................................................................................
  }

  return 0;
}

/*
** This routine decides if pIdx can be used to satisfy the ORDER BY
** clause.  If it can, it returns 1.  If pIdx cannot satisfy the
** ORDER BY clause, this routine returns 0.

**
** pOrderBy is an ORDER BY clause from a SELECT statement.  pTab is the
** left-most table in the FROM clause of that same SELECT statement and
** the table has a cursor number of "base".  pIdx is an index on pTab.

**
** nEqCol is the number of columns of pIdx that are used as equality
** constraints.  Any of these columns may be missing from the ORDER BY




** clause and the match can still be a success.
**
** All terms of the ORDER BY that match against the index must be either
** ASC or DESC.  (Terms of the ORDER BY clause past the end of a UNIQUE
** index do not need to satisfy this constraint.)  The *pbRev value is
** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if
** the ORDER BY clause is all ASC.

*/
static int isSortingIndex(
  Parse *pParse,          /* Parsing context */
  WhereMaskSet *pMaskSet, /* Mapping from table cursor numbers to bitmaps */
  Index *pIdx,            /* The index we are testing */
  int base,               /* Cursor number for the table to be sorted */
  ExprList *pOrderBy,     /* The ORDER BY clause */
  int nEqCol,             /* Number of index columns with == constraints */
  int wsFlags,            /* Index usages flags */

  int *pbRev              /* Set to 1 if ORDER BY is DESC */
){

  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) );
................................................................................
  ** the index.
  **
  ** Note that indices have pIdx->nColumn regular columns plus
  ** one additional column containing the rowid.  The rowid column
  ** of the index is also allowed to match against the ORDER BY
  ** clause.
  */
  for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<=pIdx->nColumn; i++){
    Expr *pExpr;       /* The expression of the ORDER BY pTerm */
    CollSeq *pColl;    /* The collating sequence of pExpr */
    int termSortOrder; /* Sort order for this term */
    int iColumn;       /* The i-th column of the index.  -1 for rowid */
    int iSortOrder;    /* 1 for DESC, 0 for ASC on the i-th index term */
    const char *zColl; /* Name of the collating sequence for i-th index term */

................................................................................
      }else if( i==pIdx->nColumn ){
        /* Index column i is the rowid.  All other terms match. */
        break;
      }else{
        /* If an index column fails to match and is not constrained by ==
        ** then the index cannot satisfy the ORDER BY constraint.
        */
        return 0;
      }
    }
    assert( pIdx->aSortOrder!=0 || iColumn==-1 );
    assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
    assert( iSortOrder==0 || iSortOrder==1 );
    termSortOrder = iSortOrder ^ pTerm->sortOrder;
    if( i>nEqCol ){
      if( termSortOrder!=sortOrder ){
        /* Indices can only be used if all ORDER BY terms past the
        ** equality constraints are all either DESC or ASC. */
        return 0;
      }
    }else{
      sortOrder = termSortOrder;
    }
    j++;
    pTerm++;
    if( iColumn<0 && !referencesOtherTables(pOrderBy, pMaskSet, j, base) ){
      /* If the indexed column is the primary key and everything matches
      ** so far and none of the ORDER BY terms to the right reference other
      ** tables in the join, then we are assured that the index can be used 
      ** 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
      && !referencesOtherTables(pOrderBy, pMaskSet, j, base) 



  ){
    Column *aCol = pIdx->pTable->aCol;






    /* All terms of this index match some prefix of the ORDER BY clause,
    ** the index is UNIQUE, and no terms on the tail of the ORDER BY
    ** refer to other tables in a join. So, assuming that the index entries
    ** visited contain no NULL values, then this index delivers rows in
    ** the required order.
    **
    ** It is not possible for any of the first nEqCol index fields to be
    ** NULL (since the corresponding "=" operator in the WHERE clause would 
    ** not be true). So if all remaining index columns have NOT NULL 
    ** constaints attached to them, we can be confident that the visited
    ** index entries are free of NULLs.  */
    for(i=nEqCol; i<pIdx->nColumn; i++){
      if( aCol[pIdx->aiColumn[i]].notNull==0 ) break;
    }
    return (i==pIdx->nColumn);
  }
  return 0;
}

/*
** Prepare a crude estimate of the logarithm of the input value.
** The results need not be exact.  This is only used for estimating
** the total cost of performing operations with O(logN) or O(NlogN)
** complexity.  Because N is just a guess, it is no great tragedy if
................................................................................
#define TRACE_IDX_INPUTS(A)
#define TRACE_IDX_OUTPUTS(A)
#endif

/* 
** Required because bestIndex() is called by bestOrClauseIndex() 
*/
static void bestIndex(
    Parse*, WhereClause*, struct SrcList_item*,
    Bitmask, Bitmask, WhereCost*);

/*
** This routine attempts to find an scanning strategy that can be used 
** to optimize an 'OR' expression that is part of a WHERE clause. 
**
** The table associated with FROM clause term pSrc may be either a
** regular B-Tree table or a virtual table.
*/
static void bestOrClauseIndex(
  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 */
){
#ifndef SQLITE_OMIT_OR_OPTIMIZATION


  const int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur);  /* Bitmask for pSrc */
  WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm];        /* End of pWC->a[] */
  WhereTerm *pTerm;                 /* A single term of the WHERE clause */

  /* The OR-clause optimization is disallowed if the INDEXED BY or
  ** NOT INDEXED clauses are used or if the WHERE_AND_ONLY bit is set. */
  if( pSrc->notIndexed || pSrc->pIndex!=0 ){
    return;
  }
  if( pWC->wctrlFlags & WHERE_AND_ONLY ){
    return;
  }

  /* Search the WHERE clause terms for a usable WO_OR term. */
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( pTerm->eOperator==WO_OR 
     && ((pTerm->prereqAll & ~maskSrc) & notReady)==0
     && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 
    ){
      WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
      WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
      WhereTerm *pOrTerm;
      int flags = WHERE_MULTI_OR;
      double rTotal = 0;
      double nRow = 0;
      Bitmask used = 0;






      for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){
        WhereCost sTermCost;
        WHERETRACE(("... Multi-index OR testing for term %d of %d....\n", 
          (pOrTerm - pOrWC->a), (pTerm - pWC->a)
        ));
        if( pOrTerm->eOperator==WO_AND ){
          WhereClause *pAndWC = &pOrTerm->u.pAndInfo->wc;
          bestIndex(pParse, pAndWC, pSrc, notReady, notValid, &sTermCost);
        }else if( pOrTerm->leftCursor==iCur ){
          WhereClause tempWC;
          tempWC.pParse = pWC->pParse;
          tempWC.pMaskSet = pWC->pMaskSet;
          tempWC.pOuter = pWC;
          tempWC.op = TK_AND;
          tempWC.a = pOrTerm;
          tempWC.wctrlFlags = 0;
          tempWC.nTerm = 1;
          bestIndex(pParse, &tempWC, pSrc, notReady, notValid, &sTermCost);

        }else{
          continue;
        }
        rTotal += sTermCost.rCost;
        nRow += sTermCost.plan.nRow;
        used |= sTermCost.used;
        if( rTotal>=pCost->rCost ) break;
      }

      /* If there is an ORDER BY clause, increase the scan cost to account 
      ** for the cost of the sort. */
      if( pOrderBy!=0 ){
        WHERETRACE(("... sorting increases OR cost %.9g to %.9g\n",
                    rTotal, rTotal+nRow*estLog(nRow)));
        rTotal += nRow*estLog(nRow);
      }

      /* If the cost of scanning using this OR term for optimization is
      ** less than the current cost stored in pCost, replace the contents
      ** of pCost. */
      WHERETRACE(("... multi-index OR cost=%.9g nrow=%.9g\n", rTotal, nRow));
      if( rTotal<pCost->rCost ){
        pCost->rCost = rTotal;
        pCost->used = used;
        pCost->plan.nRow = nRow;
        pCost->plan.wsFlags = flags;
        pCost->plan.u.pTerm = pTerm;
      }
    }
  }
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
}

#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
................................................................................
** If the query plan for pSrc specified in pCost is a full table scan
** and indexing is allows (if there is no NOT INDEXED clause) and it
** possible to construct a transient index that would perform better
** than a full table scan even when the cost of constructing the index
** is taken into account, then alter the query plan to use the
** transient index.
*/
static void bestAutomaticIndex(
  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 that are not available */
  WhereCost *pCost            /* Lowest cost query plan */
){
  double nTableRow;           /* Rows in the input table */
  double logN;                /* log(nTableRow) */
  double costTempIdx;         /* per-query cost of the transient index */
  WhereTerm *pTerm;           /* A single term of the WHERE clause */
  WhereTerm *pWCEnd;          /* End of pWC->a[] */
  Table *pTable;              /* Table tht might be indexed */

  if( pParse->nQueryLoop<=(double)1 ){
    /* There is no point in building an automatic index for a single scan */
    return;
  }
  if( (pParse->db->flags & SQLITE_AutoIndex)==0 ){
    /* Automatic indices are disabled at run-time */
    return;
  }
  if( (pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)!=0 ){
    /* We already have some kind of index in use for this query. */
    return;
  }
  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }
................................................................................
  }

  assert( pParse->nQueryLoop >= (double)1 );
  pTable = pSrc->pTab;
  nTableRow = pTable->nRowEst;
  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=pCost->rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

  /* Search for any equality comparison term */
  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      WHERETRACE(("auto-index reduces cost from %.1f to %.1f\n",
                    pCost->rCost, costTempIdx));
      pCost->rCost = costTempIdx;
      pCost->plan.nRow = logN + 1;
      pCost->plan.wsFlags = WHERE_TEMP_INDEX;
      pCost->used = pTerm->prereqRight;
      break;
    }
  }
}
#else
# define bestAutomaticIndex(A,B,C,D,E)  /* no-op */
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */


#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/*
** Generate code to construct the Index object for an automatic index
** and to set up the WhereLevel object pLevel so that the code generator
................................................................................

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Allocate and populate an sqlite3_index_info structure. It is the 
** responsibility of the caller to eventually release the structure
** by passing the pointer returned by this function to sqlite3_free().
*/
static sqlite3_index_info *allocateIndexInfo(
  Parse *pParse, 
  WhereClause *pWC,
  struct SrcList_item *pSrc,
  ExprList *pOrderBy
){
  int i, j;
  int nTerm;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_orderby *pIdxOrderBy;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int nOrderBy;
................................................................................

  /* If the ORDER BY clause contains only columns in the current 
  ** virtual table then allocate space for the aOrderBy part of
  ** the sqlite3_index_info structure.
  */
  nOrderBy = 0;
  if( pOrderBy ){
    for(i=0; i<pOrderBy->nExpr; i++){

      Expr *pExpr = pOrderBy->a[i].pExpr;
      if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
    }
    if( i==pOrderBy->nExpr ){
      nOrderBy = pOrderBy->nExpr;
    }
  }

  /* Allocate the sqlite3_index_info structure
  */
  pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
                           + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
................................................................................
** same virtual table.  The sqlite3_index_info structure is created
** and initialized on the first invocation and reused on all subsequent
** invocations.  The sqlite3_index_info structure is also used when
** code is generated to access the virtual table.  The whereInfoDelete() 
** routine takes care of freeing the sqlite3_index_info structure after
** everybody has finished with it.
*/
static void bestVirtualIndex(
  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 index */
  Bitmask notValid,               /* Cursors not valid for any purpose */
  ExprList *pOrderBy,             /* The order by clause */
  WhereCost *pCost,               /* Lowest cost query plan */
  sqlite3_index_info **ppIdxInfo  /* Index information passed to xBestIndex */
){
  Table *pTab = pSrc->pTab;
  sqlite3_index_info *pIdxInfo;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int i, j;
  int nOrderBy;
  double rCost;

  /* Make sure wsFlags is initialized to some sane value. Otherwise, if the 
  ** malloc in allocateIndexInfo() fails and this function returns leaving
  ** wsFlags in an uninitialized state, the caller may behave unpredictably.
  */
  memset(pCost, 0, sizeof(*pCost));
  pCost->plan.wsFlags = WHERE_VIRTUALTABLE;

  /* If the sqlite3_index_info structure has not been previously
  ** allocated and initialized, then allocate and initialize it now.
  */
  pIdxInfo = *ppIdxInfo;
  if( pIdxInfo==0 ){
    *ppIdxInfo = pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pOrderBy);
  }
  if( pIdxInfo==0 ){
    return;
  }

  /* At this point, the sqlite3_index_info structure that pIdxInfo points
  ** to will have been initialized, either during the current invocation or
................................................................................
  ** each time.
  */
  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
  pUsage = pIdxInfo->aConstraintUsage;
  for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
    j = pIdxCons->iTermOffset;
    pTerm = &pWC->a[j];
    pIdxCons->usable = (pTerm->prereqRight&notReady) ? 0 : 1;
  }
  memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
  if( pIdxInfo->needToFreeIdxStr ){
    sqlite3_free(pIdxInfo->idxStr);
  }
  pIdxInfo->idxStr = 0;
  pIdxInfo->idxNum = 0;
  pIdxInfo->needToFreeIdxStr = 0;
  pIdxInfo->orderByConsumed = 0;
  /* ((double)2) In case of SQLITE_OMIT_FLOATING_POINT... */
  pIdxInfo->estimatedCost = SQLITE_BIG_DBL / ((double)2);
  nOrderBy = pIdxInfo->nOrderBy;
  if( !pOrderBy ){
    pIdxInfo->nOrderBy = 0;
  }

  if( vtabBestIndex(pParse, pTab, pIdxInfo) ){
    return;
  }

  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++){
    if( pUsage[i].argvIndex>0 ){
      pCost->used |= pWC->a[pIdxCons[i].iTermOffset].prereqRight;
    }
  }

  /* If there is an ORDER BY clause, and the selected virtual table index
  ** does not satisfy it, increase the cost of the scan accordingly. This
  ** matches the processing for non-virtual tables in bestBtreeIndex().
  */
  rCost = pIdxInfo->estimatedCost;
  if( pOrderBy && pIdxInfo->orderByConsumed==0 ){
    rCost += estLog(rCost)*rCost;
  }

  /* The cost is not allowed to be larger than SQLITE_BIG_DBL (the
  ** inital value of lowestCost in this loop. If it is, then the
  ** (cost<lowestCost) test below will never be true.
  ** 
  ** Use "(double)2" instead of "2.0" in case OMIT_FLOATING_POINT 
  ** is defined.
  */
  if( (SQLITE_BIG_DBL/((double)2))<rCost ){
    pCost->rCost = (SQLITE_BIG_DBL/((double)2));
  }else{
    pCost->rCost = rCost;
  }
  pCost->plan.u.pVtabIdx = pIdxInfo;
  if( pIdxInfo->orderByConsumed ){
    pCost->plan.wsFlags |= WHERE_ORDERBY;
  }
  pCost->plan.nEq = 0;
  pIdxInfo->nOrderBy = nOrderBy;

  /* Try to find a more efficient access pattern by using multiple indexes
  ** to optimize an OR expression within the WHERE clause. 
  */
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifdef SQLITE_ENABLE_STAT3
/*
** Estimate the location of a particular key among all keys in an
** index.  Store the results in aStat as follows:
................................................................................
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: est=%g\n", nRowEst));
  }
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT3) */

















































/*



























** Find the best query plan for accessing a particular table.  Write the
** best query plan and its cost into the WhereCost object supplied as the
** last parameter.
**
** The lowest cost plan wins.  The cost is an estimate of the amount of
** CPU and disk I/O needed to process the requested result.
** Factors that influence cost include:
**
**    *  The estimated number of rows that will be retrieved.  (The
**       fewer the better.)
................................................................................
** then the cost is calculated in the usual way.
**
** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table 
** in the SELECT statement, then no indexes are considered. However, the 
** selected plan may still take advantage of the built-in rowid primary key
** index.
*/
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 */
  Index sPk;                  /* A fake index object for the primary key */
  tRowcnt aiRowEstPk[2];      /* The aiRowEst[] value for the sPk index */
  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
  int wsFlagMask;             /* Allowed flags in pCost->plan.wsFlag */

  /* Initialize the cost to a worst-case value */
  memset(pCost, 0, sizeof(*pCost));
  pCost->rCost = SQLITE_BIG_DBL;

  /* If the pSrc table is the right table of a LEFT JOIN then we may not
  ** use an index to satisfy IS NULL constraints on that table.  This is
  ** because columns might end up being NULL if the table does not match -
  ** a circumstance which the index cannot help us discover.  Ticket #2177.
  */
  if( pSrc->jointype & JT_LEFT ){
................................................................................
  /* Loop over all indices looking for the best one to use
  */
  for(; pProbe; pIdx=pProbe=pProbe->pNext){
    const tRowcnt * const aiRowEst = pProbe->aiRowEst;
    double cost;                /* Cost of using pProbe */
    double nRow;                /* Estimated number of rows in result set */
    double log10N = (double)1;  /* base-10 logarithm of nRow (inexact) */
    int rev;                    /* True to scan in reverse order */
    int wsFlags = 0;
    Bitmask used = 0;

    /* The following variables are populated based on the properties of
    ** index being evaluated. They are then used to determine the expected
    ** cost and number of rows returned.
    **
................................................................................
    **
    **    nInMul is set to 1.
    **
    **    If there exists a WHERE term of the form "x IN (SELECT ...)", then 
    **    the sub-select is assumed to return 25 rows for the purposes of 
    **    determining nInMul.
    **




    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.  Note that the RHS of the
    **    IN operator must be a SELECT, not a value list, for this variable
    **    to be true.
    **
    **  rangeDiv:
................................................................................
    **    space to 1/16th of its original size (rangeDiv==16).
    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **




    **  bLookup: 
    **    Boolean. True if a table lookup is required for each index entry
    **    visited.  In other words, true if this is not a covering index.
    **    This is always false for the rowid primary key index of a table.
    **    For other indexes, it is true unless all the columns of the table
    **    used by the SELECT statement are present in the index (such an
    **    index is sometimes described as a covering index).
................................................................................
    **    of column c, but the first does not because columns a and b are
    **    both available in the index.
    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             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 */
    double rangeDiv = (double)1;  /* 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_STAT3
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif





    /* Determine the values of nEq and nInMul */
    for(nEq=0; nEq<pProbe->nColumn; nEq++){
      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
      testcase( pTerm->pWC!=pWC );
      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){
................................................................................
          bInEst = 1;
        }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
          /* "x IN (value, value, ...)" */
          nInMul *= pExpr->x.pList->nExpr;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;



      }
#ifdef SQLITE_ENABLE_STAT3
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }
 
................................................................................
      testcase( wsFlags & WHERE_COLUMN_IN );
      testcase( wsFlags & WHERE_COLUMN_NULL );
      if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
        wsFlags |= WHERE_UNIQUE;
      }
    }else if( pProbe->bUnordered==0 ){
      int j = (nEq==pProbe->nColumn ? -1 : pProbe->aiColumn[nEq]);
      if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){

        WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
        WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &rangeDiv);
        if( pTop ){
          nBound = 1;
          wsFlags |= WHERE_TOP_LIMIT;
          used |= pTop->prereqRight;
          testcase( pTop->pWC!=pWC );
        }
................................................................................
      }
    }

    /* 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( isDistinctIndex(pParse, pWC, pProbe, iCur, pDistinct, nEq)
     && (wsFlags & WHERE_COLUMN_IN)==0
    ){
      bDist = 0;
      wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_DISTINCT;
    }

    /* If currently calculating the cost of using an index (not the IPK
................................................................................
    ** on one page and hence more pages have to be fetched.
    **
    ** The ANALYZE command and the sqlite_stat1 and sqlite_stat3 tables do
    ** not give us data on the relative sizes of table and index records.
    ** So this computation assumes table records are about twice as big
    ** as index records
    */
    if( wsFlags==WHERE_IDX_ONLY
     && (pWC->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
     && sqlite3GlobalConfig.bUseCis
#ifndef SQLITE_OMIT_BUILTIN_TEST
     && (pParse->db->flags & SQLITE_CoverIdxScan)==0
#endif
    ){
      /* This index is not useful for indexing, but it is a covering index.
      ** A full-scan of the index might be a little faster than a full-scan
      ** of the table, so give this case a cost slightly less than a table
      ** scan. */
      cost = aiRowEst[0]*3 + pProbe->nColumn;
      wsFlags |= WHERE_COVER_SCAN|WHERE_COLUMN_RANGE;
................................................................................
    /* Add in the estimated cost of sorting the result.  Actual experimental
    ** measurements of sorting performance in SQLite show that sorting time
    ** 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 ****/

................................................................................
    ** mask will only have one bit set - the bit for the current table.
    ** The notValid mask, on the other hand, always has all bits set for
    ** tables that are not in outer loops.  If notReady is used here instead
    ** of notValid, then a optimal index that depends on inner joins loops
    ** might be selected even when there exists an optimal index that has
    ** no such dependency.
    */
    if( nRow>2 && cost<=pCost->rCost ){
      int k;                       /* Loop counter */
      int nSkipEq = nEq;           /* Number of == constraints to skip */
      int nSkipRange = nBound;     /* Number of < constraints to skip */
      Bitmask thisTab;             /* Bitmap for pSrc */

      thisTab = getMask(pWC->pMaskSet, iCur);
      for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){
        if( pTerm->wtFlags & TERM_VIRTUAL ) continue;
        if( (pTerm->prereqAll & notValid)!=thisTab ) continue;
        if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){
          if( nSkipEq ){
            /* Ignore the first nEq equality matches since the index
            ** has already accounted for these */
            nSkipEq--;
          }else{
            /* Assume each additional equality match reduces the result
................................................................................
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((

      "%s(%s): nEq=%d nInMul=%d rangeDiv=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
      "         notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f used=0x%llx\n",

      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, (int)rangeDiv, bSort, bLookup, wsFlags,
      notReady, log10N, nRow, cost, used
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
     && (cost<pCost->rCost || (cost<=pCost->rCost && nRow<pCost->plan.nRow))
    ){
      pCost->rCost = cost;
      pCost->used = used;
      pCost->plan.nRow = nRow;
      pCost->plan.wsFlags = (wsFlags&wsFlagMask);
      pCost->plan.nEq = nEq;

      pCost->plan.u.pIdx = pIdx;
    }

    /* If there was an INDEXED BY clause, then only that one index is
    ** considered. */
    if( pSrc->pIndex ) break;

    /* Reset masks for the next index in the loop */
................................................................................
  }

  /* If there is no ORDER BY clause and the SQLITE_ReverseOrder flag
  ** is set, then reverse the order that the index will be scanned
  ** in. This is used for application testing, to help find cases
  ** where application behaviour depends on the (undefined) order that
  ** SQLite outputs rows in in the absence of an ORDER BY clause.  */
  if( !pOrderBy && pParse->db->flags & SQLITE_ReverseOrder ){
    pCost->plan.wsFlags |= WHERE_REVERSE;
  }

  assert( pOrderBy || (pCost->plan.wsFlags&WHERE_ORDERBY)==0 );
  assert( pCost->plan.u.pIdx==0 || (pCost->plan.wsFlags&WHERE_ROWID_EQ)==0 );
  assert( pSrc->pIndex==0 
       || pCost->plan.u.pIdx==0 
       || pCost->plan.u.pIdx==pSrc->pIndex 
  );

  WHERETRACE(("best index is: %s\n", 
    ((pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ? "none" : 
         pCost->plan.u.pIdx ? pCost->plan.u.pIdx->zName : "ipk")
  ));
  
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, notValid, pOrderBy, pCost);
  bestAutomaticIndex(pParse, pWC, pSrc, notReady, pCost);
  pCost->plan.wsFlags |= eqTermMask;
}

/*
** Find the query plan for accessing table pSrc->pTab. Write the
** best query plan and its cost into the WhereCost object supplied 
** as the last parameter. This function may calculate the cost of
** both real and virtual table scans.
................................................................................
**
** This function does not take ORDER BY or DISTINCT into account.  Nor
** does it remember the virtual table query plan.  All it does is compute
** the cost while determining if an OR optimization is applicable.  The
** details will be reconsidered later if the optimization is found to be
** applicable.
*/
static void bestIndex(
  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 */
  WhereCost *pCost            /* Lowest cost query plan */
){
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pSrc->pTab) ){
    sqlite3_index_info *p = 0;

    bestVirtualIndex(pParse, pWC, pSrc, notReady, notValid, 0, pCost, &p);
    if( p->needToFreeIdxStr ){
      sqlite3_free(p->idxStr);
    }
    sqlite3DbFree(pParse->db, p);
  }else
#endif
  {
    bestBtreeIndex(pParse, pWC, pSrc, notReady, notValid, 0, 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.
................................................................................
  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 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 */
  Bitmask notReady;          /* Cursors that are not yet positioned */

  WhereMaskSet *pMaskSet;    /* The expression mask set */
  WhereClause *pWC;               /* Decomposition of the WHERE clause */
  struct SrcList_item *pTabItem;  /* A single entry from pTabList */
  WhereLevel *pLevel;             /* A single level in pWInfo->a[] */
  int iFrom;                      /* First unused FROM clause element */
  int andFlags;              /* AND-ed combination of all pWC->a[].wtFlags */

  sqlite3 *db;               /* Database connection */






  /* The number of tables in the FROM clause is limited by the number of
  ** bits in a Bitmask 
  */
  testcase( pTabList->nSrc==BMS );
  if( pTabList->nSrc>BMS ){
    sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
    return 0;
................................................................................
    pWInfo = 0;
    goto whereBeginError;
  }
  pWInfo->nLevel = nTabList;
  pWInfo->pParse = pParse;
  pWInfo->pTabList = pTabList;
  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
  pWInfo->pWC = pWC = (WhereClause *)&((u8 *)pWInfo)[nByteWInfo];
  pWInfo->wctrlFlags = wctrlFlags;
  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
  pMaskSet = (WhereMaskSet*)&pWC[1];


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

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(pWC, pParse, pMaskSet, wctrlFlags);
  sqlite3ExprCodeConstants(pParse, pWhere);
  whereSplit(pWC, pWhere, TK_AND);   /* IMP: R-15842-53296 */
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
    sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL);
    pWhere = 0;
................................................................................
  ** with virtual tables.
  **
  ** Note that bitmasks are created for all pTabList->nSrc tables in
  ** pTabList, not just the first nTabList tables.  nTabList is normally
  ** equal to pTabList->nSrc but might be shortened to 1 if the
  ** WHERE_ONETABLE_ONLY flag is set.
  */
  assert( pWC->vmask==0 && pMaskSet->n==0 );
  for(i=0; i<pTabList->nSrc; i++){
    createMask(pMaskSet, pTabList->a[i].iCursor);
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( ALWAYS(pTabList->a[i].pTab) && IsVirtual(pTabList->a[i].pTab) ){
      pWC->vmask |= ((Bitmask)1 << i);
    }
#endif
  }
#ifndef NDEBUG
  {
    Bitmask toTheLeft = 0;
    for(i=0; i<pTabList->nSrc; i++){
      Bitmask m = getMask(pMaskSet, pTabList->a[i].iCursor);
      assert( (m-1)==toTheLeft );
      toTheLeft |= m;
    }
  }
#endif

  /* Analyze all of the subexpressions.  Note that exprAnalyze() might
  ** add new virtual terms onto the end of the WHERE clause.  We do not
  ** 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 && isDistinctRedundant(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[].iTabCur   The VDBE cursor for the database table
  **   pWInfo->a[].iIdxCur   The VDBE cursor for the index
  **   pWInfo->a[].pTerm     When wsFlags==WO_OR, the OR-clause term
  **
  ** This loop also figures out the nesting order of tables in the FROM
  ** clause.
  */
  notReady = ~(Bitmask)0;



  andFlags = ~0;
  WHERETRACE(("*** Optimizer Start ***\n"));
  for(i=iFrom=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){
    WhereCost bestPlan;         /* Most efficient plan seen so far */
    Index *pIdx;                /* Index for FROM table at pTabItem */
    int j;                      /* For looping over FROM tables */
    int bestJ = -1;             /* The value of j */
    Bitmask m;                  /* Bitmask value for j or bestJ */
    int isOptimal;              /* Iterator for optimal/non-optimal search */
    int nUnconstrained;         /* Number tables without INDEXED BY */
    Bitmask notIndexed;         /* Mask of tables that cannot use an index */

    memset(&bestPlan, 0, sizeof(bestPlan));
    bestPlan.rCost = SQLITE_BIG_DBL;
    WHERETRACE(("*** Begin search for loop %d ***\n", i));

    /* Loop through the remaining entries in the FROM clause to find the
    ** next nested loop. The loop tests all FROM clause entries
    ** either once or twice. 
    **
    ** The first test is always performed if there are two or more entries
    ** remaining and never performed if there is only one FROM clause entry
................................................................................
    ** this context an optimal scan is one that uses the same strategy
    ** for the given FROM clause entry as would be selected if the entry
    ** were used as the innermost nested loop.  In other words, a table
    ** is chosen such that the cost of running that table cannot be reduced
    ** by waiting for other tables to run first.  This "optimal" test works
    ** by first assuming that the FROM clause is on the inner loop and finding
    ** its query plan, then checking to see if that query plan uses any
    ** other FROM clause terms that are notReady.  If no notReady terms are
    ** used then the "optimal" query plan works.
    **
    ** Note that the WhereCost.nRow parameter for an optimal scan might
    ** not be as small as it would be if the table really were the innermost
    ** join.  The nRow value can be reduced by WHERE clause constraints
    ** that do not use indices.  But this nRow reduction only happens if the
    ** table really is the innermost join.  
    **
................................................................................
    ** as the cost of a linear scan through table t1, a simple greedy 
    ** algorithm may choose to use t2 for the outer loop, which is a much
    ** costlier approach.
    */
    nUnconstrained = 0;
    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 *pOB;       /* 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);
        pOB = (i==0) ? pOrderBy : 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, pOB,
                           &sCost, pp);
        }else 
#endif
        {
          bestBtreeIndex(pParse, pWC, pTabItem, mask, notReady, pOB,
              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
                  || sCost.plan.u.pIdx==pTabItem->pIndex );

        if( isOptimal && (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){
          notIndexed |= m;
        }

        /* Conditions under which this table becomes the best so far:
        **
        **   (1) The table must not depend on other tables that have not
        **       yet run.

        **
        **   (2) A full-table-scan plan cannot supercede indexed plan unless
        **       the full-table-scan is an "optimal" plan as defined above.
        **
        **   (3) All tables have an INDEXED BY clause or this table lacks an
        **       INDEXED BY clause or this table uses the specific
        **       index specified by its INDEXED BY clause.  This rule ensures
................................................................................
        **       will be detected and relayed back to the application later.
        **       The NEVER() comes about because rule (2) above prevents
        **       An indexable full-table-scan from reaching rule (3).
        **
        **   (4) The plan cost must be lower than prior plans or else the
        **       cost must be the same and the number of rows must be lower.
        */
        if( (sCost.used&notReady)==0                       /* (1) */
            && (bestJ<0 || (notIndexed&m)!=0               /* (2) */
                || (bestPlan.plan.wsFlags & WHERE_NOT_FULLSCAN)==0
                || (sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)
            && (nUnconstrained==0 || pTabItem->pIndex==0   /* (3) */
                || NEVER((sCost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0))
            && (bestJ<0 || sCost.rCost<bestPlan.rCost      /* (4) */
                || (sCost.rCost<=bestPlan.rCost 
                 && sCost.plan.nRow<bestPlan.plan.nRow))
        ){
          WHERETRACE(("=== table %d is best so far"
                      " with cost=%g and nRow=%g\n",
                      j, sCost.rCost, sCost.plan.nRow));

          bestPlan = sCost;
          bestJ = j;
        }
        if( doNotReorder ) break;
      }
    }
    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 ){
      pWInfo->nOBSat = pOrderBy->nExpr;
    }
    if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
      assert( pWInfo->eDistinct==0 );
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
................................................................................
        pLevel->iIdxCur = iIdxCur;
      }else{
        pLevel->iIdxCur = pParse->nTab++;
      }
    }else{
      pLevel->iIdxCur = -1;
    }
    notReady &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor);
    pLevel->iFrom = (u8)bestJ;
    if( bestPlan.plan.nRow>=(double)1 ){
      pParse->nQueryLoop *= bestPlan.plan.nRow;
    }

    /* Check that if the table scanned by this loop iteration had an
    ** INDEXED BY clause attached to it, that the named index is being
................................................................................

  /* Open all tables in the pTabList and any indices selected for
  ** searching those tables.
  */
  sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
  notReady = ~(Bitmask)0;
  pWInfo->nRowOut = (double)1;
  for(i=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){
    Table *pTab;     /* Table to open */
    int iDb;         /* Index of database containing table/index */


    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
    pLevel->iTabCur = pTabItem->iCursor;
    pWInfo->nRowOut *= pLevel->plan.nRow;
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
................................................................................
        assert( n<=pTab->nCol );
      }
    }else{
      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
    }
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->plan.wsFlags & WHERE_TEMP_INDEX)!=0 ){
      constructAutomaticIndex(pParse, pWC, pTabItem, notReady, pLevel);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
      Index *pIx = pLevel->plan.u.pIdx;
      KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
      int iIndexCur = pLevel->iIdxCur;
      assert( pIx->pSchema==pTab->pSchema );
      assert( iIndexCur>=0 );
      sqlite3VdbeAddOp4(v, OP_OpenRead, iIndexCur, pIx->tnum, iDb,
                        (char*)pKey, P4_KEYINFO_HANDOFF);
      VdbeComment((v, "%s", pIx->zName));
    }
    sqlite3CodeVerifySchema(pParse, iDb);
    notReady &= ~getMask(pWC->pMaskSet, pTabItem->iCursor);
  }
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* 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; i<nTabList; i++){
    pLevel = &pWInfo->a[i];
    explainOneScan(pParse, pTabList, pLevel, i, pLevel->iFrom, wctrlFlags);
    notReady = codeOneLoopStart(pWInfo, i, wctrlFlags, notReady);
    pWInfo->iContinue = pLevel->addrCont;
  }

#ifdef SQLITE_TEST  /* For testing and debugging use only */
  /* Record in the query plan information about the current table
  ** and the index used to access it (if any).  If the table itself
  ** is not used, its name is just '{}'.  If no index is used
  ** the index is listed as "{}".  If the primary key is used the
  ** index name is '*'.
  */
  for(i=0; i<nTabList; i++){
    char *z;
    int n;
    int w;


    pLevel = &pWInfo->a[i];
    w = pLevel->plan.wsFlags;
    pTabItem = &pTabList->a[pLevel->iFrom];
    z = pTabItem->zAlias;
    if( z==0 ) z = pTabItem->pTab->zName;
    n = sqlite3Strlen30(z);
    if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
      if( (w & WHERE_IDX_ONLY)!=0 && (w & WHERE_COVER_SCAN)==0 ){







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







 







|
|

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







 







|
|
>

<
<
|
>


|
>
>
>
>
|

<
<
<
<
|
>


<
|
|
|
<
|
|
>
|

>
|
|
|
|
>
>
|
>
>
>

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







 







|







 







|






|



|






|
|
|
<
<
<
<
<


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

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







 







|
<
<








|
<
<
<
<
<
<
<
<

>
>
|


|













|









>

>
>
>
>

<




|
|









|
>



|
|
|
|




|









|
|
|
|
|
|







 







|
|
|
|
<
<
<
|
|













|







 







|








|

|
|
|
|
|





|







 







|
|
|
|
|
<







 







|
>



|
|







 







|
|
|
|
<
<
<
<
<
<













|
|




|

|







 







|












|










|








|











|

|

|

|

|





|







 







>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
|
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>

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

|
<







 







|
|
|
|
<
<
<
<
<
<








|


|
|







 







|







 







>
>
>
>







 







>
>
>
>







 







>




|
|

>
>





>
>
>
>

|

|







 







>
>
>







 







|
>
|
|







 







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





>
|







 







|


<
|
<







 







|







 







|








|







 







>
|
|
>


|






|

|
|
|
|
|
>
|







 







|
|


|
|

|
|



|
|


|
|
|







 







|
<
<
<
<
<
<
<

|
|
>
|
|
|

|



|







 







<





>

<
<
|
|

>


>
>
>
>
>







 







|


|
>



|





|

|







 







|
|
|

|
|






|
|











|








|







 







|
>
>
>


|











|







 







|
|







 







<
|

<
<
<

|

|
<
>



|
<
<
|



|

|
|
|
<



|
<

|



|
|
|

|






|
>







 







|
|

|
|
|
|
|
|


|
|
>
|






|
|
|
|
>







 







|







 







|


>







 







|













|









|
|
|
|










|



>
>
|







263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
....
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441

1442
1443



1444

1445
1446
1447
1448
1449
1450
1451
1452
....
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614


1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625




1626
1627
1628
1629

1630
1631
1632

1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663

1664
1665
1666
1667
1668
1669
1670
....
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
....
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744





1745
1746

1747




1748

1749
1750
1751
1752
1753
1754

1755
1756
1757
1758

1759
1760
1761
1762
1763
1764













1765


1766
1767
1768
1769
1770
1771
1772
1773
....
1826
1827
1828
1829
1830
1831
1832
1833


1834
1835
1836
1837
1838
1839
1840
1841
1842








1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879

1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
....
1953
1954
1955
1956
1957
1958
1959
1960
1961
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
....
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
....
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183

2184
2185
2186
2187
2188
2189
2190
....
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
....
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346






2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
....
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
....
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
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
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948

2949
2950
2951
2952
2953
2954
2955
....
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976






2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
....
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
....
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
....
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
....
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
....
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
....
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
....
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213


3214
3215
3216
3217

3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
....
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305

3306

3307
3308
3309
3310
3311
3312
3313
....
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
....
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
....
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
....
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
....
3492
3493
3494
3495
3496
3497
3498
3499







3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
....
4785
4786
4787
4788
4789
4790
4791

4792
4793
4794
4795
4796
4797
4798


4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
....
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
....
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
....
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
....
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
....
5009
5010
5011
5012
5013
5014
5015

5016
5017



5018
5019
5020
5021

5022
5023
5024
5025
5026


5027
5028
5029
5030
5031
5032
5033
5034
5035

5036
5037
5038
5039

5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
....
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
....
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
....
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
....
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
#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 */
#define WHERE_COVER_SCAN   0x80000000  /* Full scan of a covering index */

/*
** This module contains many separate subroutines that work together to
** find the best indices to use for accessing a particular table in a query.
** An instance of the following structure holds context information about the
** index search so that it can be more easily passed between the various
** routines.
*/
typedef struct WhereBestIdx WhereBestIdx;
struct WhereBestIdx {
  Parse *pParse;                  /* Parser context */
  WhereClause *pWC;               /* The WHERE clause */
  struct SrcList_item *pSrc;      /* The FROM clause term to search */
  Bitmask notReady;               /* Mask of cursors not available */
  Bitmask notValid;               /* Cursors not available for any purpose */
  ExprList *pOrderBy;             /* The ORDER BY clause */
  ExprList *pDistinct;            /* The select-list if query is DISTINCT */
  sqlite3_index_info **ppIdxInfo; /* Index information passed to xBestIndex */
  int i, n;                       /* Which loop is being coded; # of loops */
  WhereLevel *aLevel;             /* Info about outer loops */
  WhereCost cost;                 /* Lowest cost query plan */
};

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */
  WhereMaskSet *pMaskSet,  /* Mapping from table cursor numbers to bitmasks */
................................................................................
  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
  ** an index for tables to the left of the join.
  */
  pTerm->prereqRight |= extraRight;
}

/*
** Return TRUE if the given index is UNIQUE and all columns past the
** first nSkip columns are NOT NULL.
*/
static int indexIsUniqueNotNull(Index *pIdx, int nSkip){
  Table *pTab = pIdx->pTable;
  int i;
  if( pIdx->onError==OE_None ) return 0;
  for(i=nSkip; i<pIdx->nColumn; i++){

    int j = pIdx->aiColumn[i];
    if( j>=0 && pTab->aCol[j].notNull==0 ) return 0;



  }

  return 1;
}

/*
** This function searches the expression list passed as the second argument
** for an expression of type TK_COLUMN that refers to the same column and
** uses the same collation sequence as the iCol'th column of index pIdx.
** Argument iBase is the cursor number used for the table that pIdx refers
................................................................................
  }

  return 0;
}

/*
** This routine decides if pIdx can be used to satisfy the ORDER BY
** clause, either in whole or in part.  The return value is the 
** cumulative number of terms in the ORDER BY clause that are satisfied
** by the index pIdx and other indices in outer loops.
**


** The table being queried has a cursor number of "base".  pIdx is the
** index that is postulated for use to access the table.
**
** nEqCol is the number of columns of pIdx that are used as equality
** constraints and where the other side of the == is an ordered column
** or constant.  An "order column" in the previous sentence means a column
** in table from an outer loop whose values will always appear in the 
** correct order due to othre index, or because the outer loop generates
** a unique result.  Any of the first nEqCol columns of pIdx may be missing
** from the ORDER BY clause and the match can still be a success.
**




** The *pbRev value is set to 0 order 1 depending on whether or not
** pIdx should be run in the forward order or in reverse order.
*/
static int isSortingIndex(

  WhereBestIdx *p,    /* Best index search context */
  Index *pIdx,        /* The index we are testing */
  int base,           /* Cursor number for the table to be sorted */

  int nEqCol,         /* Number of index columns with ordered == constraints */
  int wsFlags,        /* Index usages flags */
  int bOuterRev,      /* True if outer loops scan in reverse order */
  int *pbRev          /* Set to 1 for reverse-order scan of pIdx */
){
  int i;                        /* Number of pIdx terms used */
  int j;                        /* Number of ORDER BY terms satisfied */
  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 */
  ExprList *pOrderBy;           /* The ORDER BY clause */
  Parse *pParse = p->pParse;    /* Parser context */
  sqlite3 *db = pParse->db;     /* Database connection */
  int nPriorSat;                /* ORDER BY terms satisfied by outer loops */
  int seenRowid = 0;            /* True if an ORDER BY rowid term is seen */
  int nEqOneRow;                /* Idx columns that ref unique values */

  if( p->i==0 ){
    nPriorSat = 0;
    nEqOneRow = nEqCol;
  }else{
    if( OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0;
    nPriorSat = p->aLevel[p->i-1].plan.nOBSat;
    sortOrder = bOuterRev;
    nEqOneRow = 0;
  }
  if( p->i>0 && nEqCol==0 /*&& !allOuterLoopsUnique(p)*/ ) return nPriorSat;
  pOrderBy = p->pOrderBy;
  if( !pOrderBy ) return nPriorSat;
  if( wsFlags & WHERE_COLUMN_IN ) return nPriorSat;
  if( pIdx->bUnordered ) return nPriorSat;

  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) );
................................................................................
  ** the index.
  **
  ** Note that indices have pIdx->nColumn regular columns plus
  ** one additional column containing the rowid.  The rowid column
  ** of the index is also allowed to match against the ORDER BY
  ** clause.
  */
  for(i=0,j=nPriorSat,pTerm=&pOrderBy->a[j]; j<nTerm && i<=pIdx->nColumn; i++){
    Expr *pExpr;       /* The expression of the ORDER BY pTerm */
    CollSeq *pColl;    /* The collating sequence of pExpr */
    int termSortOrder; /* Sort order for this term */
    int iColumn;       /* The i-th column of the index.  -1 for rowid */
    int iSortOrder;    /* 1 for DESC, 0 for ASC on the i-th index term */
    const char *zColl; /* Name of the collating sequence for i-th index term */

................................................................................
      }else if( i==pIdx->nColumn ){
        /* Index column i is the rowid.  All other terms match. */
        break;
      }else{
        /* If an index column fails to match and is not constrained by ==
        ** then the index cannot satisfy the ORDER BY constraint.
        */
        return nPriorSat;
      }
    }
    assert( pIdx->aSortOrder!=0 || iColumn==-1 );
    assert( pTerm->sortOrder==0 || pTerm->sortOrder==1 );
    assert( iSortOrder==0 || iSortOrder==1 );
    termSortOrder = iSortOrder ^ pTerm->sortOrder;
    if( i>nEqOneRow ){
      if( termSortOrder!=sortOrder ){
        /* Indices can only be used if all ORDER BY terms past the
        ** equality constraints are all either DESC or ASC. */
        break;
      }
    }else{
      sortOrder = termSortOrder;
    }
    j++;
    pTerm++;
    if( iColumn<0 ){
      seenRowid = 1;
      break;





    }
  }

  *pbRev = sortOrder;






  /* If there was an "ORDER BY rowid" term that matched, or it is only
  ** possible for a single row from this table to match, then skip over
  ** any additional ORDER BY terms dealing with this table.
  */
  if( seenRowid ||
     (   (wsFlags & WHERE_COLUMN_NULL)==0

      && i>=pIdx->nColumn
      && indexIsUniqueNotNull(pIdx, nEqCol)
     )
  ){

    /* Advance j over additional ORDER BY terms associated with base */
    WhereMaskSet *pMS = p->pWC->pMaskSet;
    Bitmask m = ~getMask(pMS, base);
    while( j<nTerm && (exprTableUsage(pMS, pOrderBy->a[j].pExpr)&m)==0 ){
      j++;
    }













  }


  return j;
}

/*
** Prepare a crude estimate of the logarithm of the input value.
** The results need not be exact.  This is only used for estimating
** the total cost of performing operations with O(logN) or O(NlogN)
** complexity.  Because N is just a guess, it is no great tragedy if
................................................................................
#define TRACE_IDX_INPUTS(A)
#define TRACE_IDX_OUTPUTS(A)
#endif

/* 
** Required because bestIndex() is called by bestOrClauseIndex() 
*/
static void bestIndex(WhereBestIdx*);



/*
** This routine attempts to find an scanning strategy that can be used 
** to optimize an 'OR' expression that is part of a WHERE clause. 
**
** The table associated with FROM clause term pSrc may be either a
** regular B-Tree table or a virtual table.
*/
static void bestOrClauseIndex(WhereBestIdx *p){








#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  WhereClause *pWC = p->pWC;           /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc; /* The FROM clause term to search */
  const int iCur = pSrc->iCursor;      /* The cursor of the table  */
  const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur);  /* Bitmask for pSrc */
  WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm];        /* End of pWC->a[] */
  WhereTerm *pTerm;                    /* A single term of the WHERE clause */

  /* The OR-clause optimization is disallowed if the INDEXED BY or
  ** NOT INDEXED clauses are used or if the WHERE_AND_ONLY bit is set. */
  if( pSrc->notIndexed || pSrc->pIndex!=0 ){
    return;
  }
  if( pWC->wctrlFlags & WHERE_AND_ONLY ){
    return;
  }

  /* Search the WHERE clause terms for a usable WO_OR term. */
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( pTerm->eOperator==WO_OR 
     && ((pTerm->prereqAll & ~maskSrc) & p->notReady)==0
     && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 
    ){
      WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
      WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
      WhereTerm *pOrTerm;
      int flags = WHERE_MULTI_OR;
      double rTotal = 0;
      double nRow = 0;
      Bitmask used = 0;
      WhereBestIdx sBOI;

      sBOI = *p;
      sBOI.pOrderBy = 0;
      sBOI.pDistinct = 0;
      sBOI.ppIdxInfo = 0;
      for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){

        WHERETRACE(("... Multi-index OR testing for term %d of %d....\n", 
          (pOrTerm - pOrWC->a), (pTerm - pWC->a)
        ));
        if( pOrTerm->eOperator==WO_AND ){
          sBOI.pWC = &pOrTerm->u.pAndInfo->wc;
          bestIndex(&sBOI);
        }else if( pOrTerm->leftCursor==iCur ){
          WhereClause tempWC;
          tempWC.pParse = pWC->pParse;
          tempWC.pMaskSet = pWC->pMaskSet;
          tempWC.pOuter = pWC;
          tempWC.op = TK_AND;
          tempWC.a = pOrTerm;
          tempWC.wctrlFlags = 0;
          tempWC.nTerm = 1;
          sBOI.pWC = &tempWC;
          bestIndex(&sBOI);
        }else{
          continue;
        }
        rTotal += sBOI.cost.rCost;
        nRow += sBOI.cost.plan.nRow;
        used |= sBOI.cost.used;
        if( rTotal>=p->cost.rCost ) break;
      }

      /* If there is an ORDER BY clause, increase the scan cost to account 
      ** for the cost of the sort. */
      if( p->pOrderBy!=0 ){
        WHERETRACE(("... sorting increases OR cost %.9g to %.9g\n",
                    rTotal, rTotal+nRow*estLog(nRow)));
        rTotal += nRow*estLog(nRow);
      }

      /* If the cost of scanning using this OR term for optimization is
      ** less than the current cost stored in pCost, replace the contents
      ** of pCost. */
      WHERETRACE(("... multi-index OR cost=%.9g nrow=%.9g\n", rTotal, nRow));
      if( rTotal<p->cost.rCost ){
        p->cost.rCost = rTotal;
        p->cost.used = used;
        p->cost.plan.nRow = nRow;
        p->cost.plan.wsFlags = flags;
        p->cost.plan.u.pTerm = pTerm;
      }
    }
  }
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
}

#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
................................................................................
** If the query plan for pSrc specified in pCost is a full table scan
** and indexing is allows (if there is no NOT INDEXED clause) and it
** possible to construct a transient index that would perform better
** than a full table scan even when the cost of constructing the index
** is taken into account, then alter the query plan to use the
** transient index.
*/
static void bestAutomaticIndex(WhereBestIdx *p){
  Parse *pParse = p->pParse;            /* The parsing context */
  WhereClause *pWC = p->pWC;            /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc;  /* The FROM clause term to search */



  double nTableRow;                     /* Rows in the input table */
  double logN;                          /* log(nTableRow) */
  double costTempIdx;         /* per-query cost of the transient index */
  WhereTerm *pTerm;           /* A single term of the WHERE clause */
  WhereTerm *pWCEnd;          /* End of pWC->a[] */
  Table *pTable;              /* Table tht might be indexed */

  if( pParse->nQueryLoop<=(double)1 ){
    /* There is no point in building an automatic index for a single scan */
    return;
  }
  if( (pParse->db->flags & SQLITE_AutoIndex)==0 ){
    /* Automatic indices are disabled at run-time */
    return;
  }
  if( (p->cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0 ){
    /* We already have some kind of index in use for this query. */
    return;
  }
  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }
................................................................................
  }

  assert( pParse->nQueryLoop >= (double)1 );
  pTable = pSrc->pTab;
  nTableRow = pTable->nRowEst;
  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=p->cost.rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

  /* Search for any equality comparison term */
  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, p->notReady) ){
      WHERETRACE(("auto-index reduces cost from %.1f to %.1f\n",
                    p->cost.rCost, costTempIdx));
      p->cost.rCost = costTempIdx;
      p->cost.plan.nRow = logN + 1;
      p->cost.plan.wsFlags = WHERE_TEMP_INDEX;
      p->cost.used = pTerm->prereqRight;
      break;
    }
  }
}
#else
# define bestAutomaticIndex(A)  /* no-op */
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */


#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/*
** Generate code to construct the Index object for an automatic index
** and to set up the WhereLevel object pLevel so that the code generator
................................................................................

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Allocate and populate an sqlite3_index_info structure. It is the 
** responsibility of the caller to eventually release the structure
** by passing the pointer returned by this function to sqlite3_free().
*/
static sqlite3_index_info *allocateIndexInfo(WhereBestIdx *p){
  Parse *pParse = p->pParse; 
  WhereClause *pWC = p->pWC;
  struct SrcList_item *pSrc = p->pSrc;
  ExprList *pOrderBy = p->pOrderBy;

  int i, j;
  int nTerm;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_orderby *pIdxOrderBy;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int nOrderBy;
................................................................................

  /* If the ORDER BY clause contains only columns in the current 
  ** virtual table then allocate space for the aOrderBy part of
  ** the sqlite3_index_info structure.
  */
  nOrderBy = 0;
  if( pOrderBy ){
    int n = pOrderBy->nExpr;
    for(i=0; i<n; i++){
      Expr *pExpr = pOrderBy->a[i].pExpr;
      if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
    }
    if( i==n){
      nOrderBy = n;
    }
  }

  /* Allocate the sqlite3_index_info structure
  */
  pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
                           + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
................................................................................
** same virtual table.  The sqlite3_index_info structure is created
** and initialized on the first invocation and reused on all subsequent
** invocations.  The sqlite3_index_info structure is also used when
** code is generated to access the virtual table.  The whereInfoDelete() 
** routine takes care of freeing the sqlite3_index_info structure after
** everybody has finished with it.
*/
static void bestVirtualIndex(WhereBestIdx *p){
  Parse *pParse = p->pParse;      /* The parsing context */
  WhereClause *pWC = p->pWC;      /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc; /* The FROM clause term to search */






  Table *pTab = pSrc->pTab;
  sqlite3_index_info *pIdxInfo;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int i, j;
  int nOrderBy;
  double rCost;

  /* Make sure wsFlags is initialized to some sane value. Otherwise, if the 
  ** malloc in allocateIndexInfo() fails and this function returns leaving
  ** wsFlags in an uninitialized state, the caller may behave unpredictably.
  */
  memset(&p->cost, 0, sizeof(p->cost));
  p->cost.plan.wsFlags = WHERE_VIRTUALTABLE;

  /* If the sqlite3_index_info structure has not been previously
  ** allocated and initialized, then allocate and initialize it now.
  */
  pIdxInfo = *p->ppIdxInfo;
  if( pIdxInfo==0 ){
    *p->ppIdxInfo = pIdxInfo = allocateIndexInfo(p);
  }
  if( pIdxInfo==0 ){
    return;
  }

  /* At this point, the sqlite3_index_info structure that pIdxInfo points
  ** to will have been initialized, either during the current invocation or
................................................................................
  ** each time.
  */
  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
  pUsage = pIdxInfo->aConstraintUsage;
  for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
    j = pIdxCons->iTermOffset;
    pTerm = &pWC->a[j];
    pIdxCons->usable = (pTerm->prereqRight&p->notReady) ? 0 : 1;
  }
  memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
  if( pIdxInfo->needToFreeIdxStr ){
    sqlite3_free(pIdxInfo->idxStr);
  }
  pIdxInfo->idxStr = 0;
  pIdxInfo->idxNum = 0;
  pIdxInfo->needToFreeIdxStr = 0;
  pIdxInfo->orderByConsumed = 0;
  /* ((double)2) In case of SQLITE_OMIT_FLOATING_POINT... */
  pIdxInfo->estimatedCost = SQLITE_BIG_DBL / ((double)2);
  nOrderBy = pIdxInfo->nOrderBy;
  if( !p->pOrderBy ){
    pIdxInfo->nOrderBy = 0;
  }

  if( vtabBestIndex(pParse, pTab, pIdxInfo) ){
    return;
  }

  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++){
    if( pUsage[i].argvIndex>0 ){
      p->cost.used |= pWC->a[pIdxCons[i].iTermOffset].prereqRight;
    }
  }

  /* If there is an ORDER BY clause, and the selected virtual table index
  ** does not satisfy it, increase the cost of the scan accordingly. This
  ** matches the processing for non-virtual tables in bestBtreeIndex().
  */
  rCost = pIdxInfo->estimatedCost;
  if( p->pOrderBy && pIdxInfo->orderByConsumed==0 ){
    rCost += estLog(rCost)*rCost;
  }

  /* The cost is not allowed to be larger than SQLITE_BIG_DBL (the
  ** inital value of lowestCost in this loop. If it is, then the
  ** (cost<lowestCost) test below will never be true.
  ** 
  ** Use "(double)2" instead of "2.0" in case OMIT_FLOATING_POINT 
  ** is defined.
  */
  if( (SQLITE_BIG_DBL/((double)2))<rCost ){
    p->cost.rCost = (SQLITE_BIG_DBL/((double)2));
  }else{
    p->cost.rCost = rCost;
  }
  p->cost.plan.u.pVtabIdx = pIdxInfo;
  if( pIdxInfo->orderByConsumed ){
    p->cost.plan.wsFlags |= WHERE_ORDERBY;
  }
  p->cost.plan.nEq = 0;
  pIdxInfo->nOrderBy = nOrderBy;

  /* Try to find a more efficient access pattern by using multiple indexes
  ** to optimize an OR expression within the WHERE clause. 
  */
  bestOrClauseIndex(p);
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifdef SQLITE_ENABLE_STAT3
/*
** Estimate the location of a particular key among all keys in an
** index.  Store the results in aStat as follows:
................................................................................
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: est=%g\n", nRowEst));
  }
  return rc;
}
#endif /* defined(SQLITE_ENABLE_STAT3) */

/*
** Check to see if column iCol of the table with cursor iTab will appear
** in sorted order according to the current query plan.  Return true if
** it will and false if not.  
**
** If *pbRev is initially 2 (meaning "unknown") then set *pbRev to the
** sort order of iTab.iCol.  If *pbRev is 0 or 1 but does not match
** the sort order of iTab.iCol, then consider the column to be unordered.
*/
static int isOrderedColumn(WhereBestIdx *p, int iTab, int iCol, int *pbRev){
  int i, j;
  WhereLevel *pLevel = &p->aLevel[p->i-1];
  Index *pIdx;
  u8 sortOrder;
  for(i=p->i-1; i>=0; i--, pLevel--){
    if( pLevel->iTabCur!=iTab ) continue;
    if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
      pIdx = pLevel->plan.u.pIdx;
      if( iCol<0 ){
        sortOrder = 0;
        testcase( (pLevel->plan.wsFlags & WHERE_REVERSE)!=0 );
      }else{
        for(j=0; j<pIdx->nColumn; j++){
          if( iCol==pIdx->aiColumn[j] ) break;
        }
        if( j>=pIdx->nColumn ) return 0;
        sortOrder = pIdx->aSortOrder[j];
        testcase( (pLevel->plan.wsFlags & WHERE_REVERSE)!=0 );
      }
    }else{
      if( iCol!=(-1) ) return 0;
      sortOrder = 0;
      testcase( (pLevel->plan.wsFlags & WHERE_REVERSE)!=0 );
    }
    if( (pLevel->plan.wsFlags & WHERE_REVERSE)!=0 ){
      assert( sortOrder==0 || sortOrder==1 );
      testcase( sortOrder==1 );
      sortOrder = 1 - sortOrder;
    }
    if( *pbRev==2 ){
      *pbRev = sortOrder;
      return 1;
    }
    return (*pbRev==sortOrder);
  }
  return 0;
}

/*
** pTerm is an == constraint.  Check to see if the other side of
** the == is a constant or a value that is guaranteed to be ordered
** by outer loops.  Return 1 if pTerm is ordered, and 0 if not.
*/
static int isOrderedTerm(WhereBestIdx *p, WhereTerm *pTerm, int *pbRev){
  Expr *pExpr = pTerm->pExpr;
  assert( pExpr->op==TK_EQ );
  assert( pExpr->pLeft!=0 && pExpr->pLeft->op==TK_COLUMN );
  assert( pExpr->pRight!=0 );
  if( p->i==0 ){
    return 1;  /* All == are ordered in the outer loop */
  }
  if( pTerm->prereqRight==0 ){
    return 1;  /* RHS of the == is a constant */
  }
  if( pExpr->pRight->op==TK_COLUMN 
   && isOrderedColumn(p, pExpr->pRight->iTable, pExpr->pRight->iColumn, pbRev)
  ){
    return 1;
  }

  /* If we cannot prove that the constraint is ordered, assume it is not */
  return 0;
}


/*
** Find the best query plan for accessing a particular table.  Write the
** best query plan and its cost into the p->cost.

**
** The lowest cost plan wins.  The cost is an estimate of the amount of
** CPU and disk I/O needed to process the requested result.
** Factors that influence cost include:
**
**    *  The estimated number of rows that will be retrieved.  (The
**       fewer the better.)
................................................................................
** then the cost is calculated in the usual way.
**
** If a NOT INDEXED clause (pSrc->notIndexed!=0) was attached to the table 
** in the SELECT statement, then no indexes are considered. However, the 
** selected plan may still take advantage of the built-in rowid primary key
** index.
*/
static void bestBtreeIndex(WhereBestIdx *p){
  Parse *pParse = p->pParse;  /* The parsing context */
  WhereClause *pWC = p->pWC;  /* The WHERE clause */
  struct SrcList_item *pSrc = p->pSrc; /* The FROM clause term to search */






  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 */
  Index sPk;                  /* A fake index object for the primary key */
  tRowcnt aiRowEstPk[2];      /* The aiRowEst[] value for the sPk index */
  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
  int wsFlagMask;             /* Allowed flags in p->cost.plan.wsFlag */

  /* Initialize the cost to a worst-case value */
  memset(&p->cost, 0, sizeof(p->cost));
  p->cost.rCost = SQLITE_BIG_DBL;

  /* If the pSrc table is the right table of a LEFT JOIN then we may not
  ** use an index to satisfy IS NULL constraints on that table.  This is
  ** because columns might end up being NULL if the table does not match -
  ** a circumstance which the index cannot help us discover.  Ticket #2177.
  */
  if( pSrc->jointype & JT_LEFT ){
................................................................................
  /* Loop over all indices looking for the best one to use
  */
  for(; pProbe; pIdx=pProbe=pProbe->pNext){
    const tRowcnt * const aiRowEst = pProbe->aiRowEst;
    double cost;                /* Cost of using pProbe */
    double nRow;                /* Estimated number of rows in result set */
    double log10N = (double)1;  /* base-10 logarithm of nRow (inexact) */
    int bRev = 2;               /* 0=forward scan.  1=reverse.  2=undecided */
    int wsFlags = 0;
    Bitmask used = 0;

    /* The following variables are populated based on the properties of
    ** index being evaluated. They are then used to determine the expected
    ** cost and number of rows returned.
    **
................................................................................
    **
    **    nInMul is set to 1.
    **
    **    If there exists a WHERE term of the form "x IN (SELECT ...)", then 
    **    the sub-select is assumed to return 25 rows for the purposes of 
    **    determining nInMul.
    **
    **  nOrdered:
    **    The number of equality terms that are constrainted by outer loop
    **    variables that are well-ordered.
    **
    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.  Note that the RHS of the
    **    IN operator must be a SELECT, not a value list, for this variable
    **    to be true.
    **
    **  rangeDiv:
................................................................................
    **    space to 1/16th of its original size (rangeDiv==16).
    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **
    **  bDistinct:
    **    Boolean. True if there is a DISTINCT clause that will require an 
    **    external btree.
    **
    **  bLookup: 
    **    Boolean. True if a table lookup is required for each index entry
    **    visited.  In other words, true if this is not a covering index.
    **    This is always false for the rowid primary key index of a table.
    **    For other indexes, it is true unless all the columns of the table
    **    used by the SELECT statement are present in the index (such an
    **    index is sometimes described as a covering index).
................................................................................
    **    of column c, but the first does not because columns a and b are
    **    both available in the index.
    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;                      /* Number of == or IN terms matching index */
    int nOrdered;                 /* Number of ordered terms matching index */
    int bInEst = 0;               /* True if "x IN (SELECT...)" seen */
    int nInMul = 1;               /* Number of distinct equalities to lookup */
    double rangeDiv = (double)1;  /* Estimated reduction in search space */
    int nBound = 0;               /* Number of range constraints seen */
    int bSort;                    /* True if external sort required */
    int bDist;                    /* True if index cannot help with DISTINCT */
    int bLookup = 0;              /* True if not a covering index */
    int nOBSat = 0;               /* Number of ORDER BY terms satisfied */
    int nOrderBy;                 /* Number of ORDER BY terms */
    WhereTerm *pTerm;             /* A single term of the WHERE clause */
#ifdef SQLITE_ENABLE_STAT3
    WhereTerm *pFirstTerm = 0;    /* First term matching the index */
#endif

    nOrderBy = p->pOrderBy ? p->pOrderBy->nExpr : 0;
    bSort = nOrderBy>0 && (p->i==0 || p->aLevel[p->i-1].plan.nOBSat<nOrderBy);
    bDist = p->i==0 && p->pDistinct!=0;

    /* Determine the values of nEq and nInMul */
    for(nEq=nOrdered=0; nEq<pProbe->nColumn; nEq++){
      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, p->notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
      testcase( pTerm->pWC!=pWC );
      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){
................................................................................
          bInEst = 1;
        }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
          /* "x IN (value, value, ...)" */
          nInMul *= pExpr->x.pList->nExpr;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;
        if( nEq==nOrdered ) nOrdered++;
      }else if( bSort && nEq==nOrdered && isOrderedTerm(p, pTerm, &bRev) ){
        nOrdered++;
      }
#ifdef SQLITE_ENABLE_STAT3
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }
 
................................................................................
      testcase( wsFlags & WHERE_COLUMN_IN );
      testcase( wsFlags & WHERE_COLUMN_NULL );
      if( (wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_NULL))==0 ){
        wsFlags |= WHERE_UNIQUE;
      }
    }else if( pProbe->bUnordered==0 ){
      int j = (nEq==pProbe->nColumn ? -1 : pProbe->aiColumn[nEq]);
      if( findTerm(pWC, iCur, j, p->notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
        WhereTerm *pTop, *pBtm;
        pTop = findTerm(pWC, iCur, j, p->notReady, WO_LT|WO_LE, pIdx);
        pBtm = findTerm(pWC, iCur, j, p->notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &rangeDiv);
        if( pTop ){
          nBound = 1;
          wsFlags |= WHERE_TOP_LIMIT;
          used |= pTop->prereqRight;
          testcase( pTop->pWC!=pWC );
        }
................................................................................
      }
    }

    /* 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.  */
    assert( bRev>=0 && bRev<=2 );
    if( bSort ){
      testcase( bRev==0 );
      testcase( bRev==1 );
      testcase( bRev==2 );
      nOBSat = isSortingIndex(p, pProbe, iCur, nOrdered,


                              wsFlags, bRev&1, &bRev);
      if( nOrderBy==nOBSat ){
        bSort = 0;
        wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;

      }
      if( bRev & 1 ) wsFlags |= WHERE_REVERSE;
    }

    /* 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( bDist
     && isDistinctIndex(pParse, pWC, pProbe, iCur, p->pDistinct, nEq)
     && (wsFlags & WHERE_COLUMN_IN)==0
    ){
      bDist = 0;
      wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_DISTINCT;
    }

    /* If currently calculating the cost of using an index (not the IPK
................................................................................
    ** on one page and hence more pages have to be fetched.
    **
    ** The ANALYZE command and the sqlite_stat1 and sqlite_stat3 tables do
    ** not give us data on the relative sizes of table and index records.
    ** So this computation assumes table records are about twice as big
    ** as index records
    */
    if( (wsFlags&~WHERE_REVERSE)==WHERE_IDX_ONLY
     && (pWC->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
     && sqlite3GlobalConfig.bUseCis

     && OptimizationEnabled(pParse->db, SQLITE_CoverIdxScan)

    ){
      /* This index is not useful for indexing, but it is a covering index.
      ** A full-scan of the index might be a little faster than a full-scan
      ** of the table, so give this case a cost slightly less than a table
      ** scan. */
      cost = aiRowEst[0]*3 + pProbe->nColumn;
      wsFlags |= WHERE_COVER_SCAN|WHERE_COLUMN_RANGE;
................................................................................
    /* Add in the estimated cost of sorting the result.  Actual experimental
    ** measurements of sorting performance in SQLite show that sorting time
    ** 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*(nOrderBy - nOBSat)/nOrderBy)*3;
    }
    if( bDist ){
      cost += nRow*estLog(nRow)*3;
    }

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

................................................................................
    ** mask will only have one bit set - the bit for the current table.
    ** The notValid mask, on the other hand, always has all bits set for
    ** tables that are not in outer loops.  If notReady is used here instead
    ** of notValid, then a optimal index that depends on inner joins loops
    ** might be selected even when there exists an optimal index that has
    ** no such dependency.
    */
    if( nRow>2 && cost<=p->cost.rCost ){
      int k;                       /* Loop counter */
      int nSkipEq = nEq;           /* Number of == constraints to skip */
      int nSkipRange = nBound;     /* Number of < constraints to skip */
      Bitmask thisTab;             /* Bitmap for pSrc */

      thisTab = getMask(pWC->pMaskSet, iCur);
      for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){
        if( pTerm->wtFlags & TERM_VIRTUAL ) continue;
        if( (pTerm->prereqAll & p->notValid)!=thisTab ) continue;
        if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){
          if( nSkipEq ){
            /* Ignore the first nEq equality matches since the index
            ** has already accounted for these */
            nSkipEq--;
          }else{
            /* Assume each additional equality match reduces the result
................................................................................
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((
      "%s(%s):\n"
      "    nEq=%d nInMul=%d rangeDiv=%d bSort=%d bLookup=%d wsFlags=0x%08x\n"
      "    notReady=0x%llx log10N=%.1f nRow=%.1f cost=%.1f\n"
      "    used=0x%llx nOrdered=%d nOBSat=%d\n",
      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, (int)rangeDiv, bSort, bLookup, wsFlags,
      p->notReady, log10N, nRow, cost, used, nOrdered, nOBSat
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
     && (cost<p->cost.rCost || (cost<=p->cost.rCost && nRow<p->cost.plan.nRow))
    ){
      p->cost.rCost = cost;
      p->cost.used = used;
      p->cost.plan.nRow = nRow;
      p->cost.plan.wsFlags = (wsFlags&wsFlagMask);
      p->cost.plan.nEq = nEq;
      p->cost.plan.nOBSat = nOBSat;
      p->cost.plan.u.pIdx = pIdx;
    }

    /* If there was an INDEXED BY clause, then only that one index is
    ** considered. */
    if( pSrc->pIndex ) break;

    /* Reset masks for the next index in the loop */
................................................................................
  }

  /* If there is no ORDER BY clause and the SQLITE_ReverseOrder flag
  ** is set, then reverse the order that the index will be scanned
  ** in. This is used for application testing, to help find cases
  ** where application behaviour depends on the (undefined) order that
  ** SQLite outputs rows in in the absence of an ORDER BY clause.  */
  if( !p->pOrderBy && pParse->db->flags & SQLITE_ReverseOrder ){
    p->cost.plan.wsFlags |= WHERE_REVERSE;
  }

  assert( p->pOrderBy || (p->cost.plan.wsFlags&WHERE_ORDERBY)==0 );
  assert( p->cost.plan.u.pIdx==0 || (p->cost.plan.wsFlags&WHERE_ROWID_EQ)==0 );
  assert( pSrc->pIndex==0 
       || p->cost.plan.u.pIdx==0 
       || p->cost.plan.u.pIdx==pSrc->pIndex 
  );

  WHERETRACE(("best index is: %s\n", 
    ((p->cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ? "none" : 
         p->cost.plan.u.pIdx ? p->cost.plan.u.pIdx->zName : "ipk")
  ));
  
  bestOrClauseIndex(p);
  bestAutomaticIndex(p);
  p->cost.plan.wsFlags |= eqTermMask;
}

/*
** Find the query plan for accessing table pSrc->pTab. Write the
** best query plan and its cost into the WhereCost object supplied 
** as the last parameter. This function may calculate the cost of
** both real and virtual table scans.
................................................................................
**
** This function does not take ORDER BY or DISTINCT into account.  Nor
** does it remember the virtual table query plan.  All it does is compute
** the cost while determining if an OR optimization is applicable.  The
** details will be reconsidered later if the optimization is found to be
** applicable.
*/
static void bestIndex(WhereBestIdx *p){







#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(p->pSrc->pTab) ){
    sqlite3_index_info *pIdxInfo = 0;
    p->ppIdxInfo = &pIdxInfo;
    bestVirtualIndex(p);
    if( pIdxInfo->needToFreeIdxStr ){
      sqlite3_free(pIdxInfo->idxStr);
    }
    sqlite3DbFree(p->pParse->db, pIdxInfo);
  }else
#endif
  {
    bestBtreeIndex(p);
  }
}

/*
** 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.
................................................................................
  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 */
  Bitmask notReady;          /* Cursors that are not yet positioned */
  WhereBestIdx sWBI;         /* Best index search context */
  WhereMaskSet *pMaskSet;    /* The expression mask set */


  WhereLevel *pLevel;        /* A single level in pWInfo->a[] */
  int iFrom;                 /* First unused FROM clause element */
  int andFlags;              /* AND-ed combination of all pWC->a[].wtFlags */
  int ii;                    /* Loop counter */
  sqlite3 *db;               /* Database connection */


  /* Variable initialization */
  memset(&sWBI, 0, sizeof(sWBI));
  sWBI.pParse = pParse;

  /* The number of tables in the FROM clause is limited by the number of
  ** bits in a Bitmask 
  */
  testcase( pTabList->nSrc==BMS );
  if( pTabList->nSrc>BMS ){
    sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
    return 0;
................................................................................
    pWInfo = 0;
    goto whereBeginError;
  }
  pWInfo->nLevel = nTabList;
  pWInfo->pParse = pParse;
  pWInfo->pTabList = pTabList;
  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
  pWInfo->pWC = sWBI.pWC = (WhereClause *)&((u8 *)pWInfo)[nByteWInfo];
  pWInfo->wctrlFlags = wctrlFlags;
  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
  pMaskSet = (WhereMaskSet*)&sWBI.pWC[1];
  sWBI.aLevel = pWInfo->a;

  /* 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(sWBI.pWC, pParse, pMaskSet, wctrlFlags);
  sqlite3ExprCodeConstants(pParse, pWhere);
  whereSplit(sWBI.pWC, pWhere, TK_AND);   /* IMP: R-15842-53296 */
    
  /* Special case: a WHERE clause that is constant.  Evaluate the
  ** expression and either jump over all of the code or fall thru.
  */
  if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
    sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL);
    pWhere = 0;
................................................................................
  ** with virtual tables.
  **
  ** Note that bitmasks are created for all pTabList->nSrc tables in
  ** pTabList, not just the first nTabList tables.  nTabList is normally
  ** equal to pTabList->nSrc but might be shortened to 1 if the
  ** WHERE_ONETABLE_ONLY flag is set.
  */
  assert( sWBI.pWC->vmask==0 && pMaskSet->n==0 );
  for(ii=0; ii<pTabList->nSrc; ii++){
    createMask(pMaskSet, pTabList->a[ii].iCursor);
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( ALWAYS(pTabList->a[ii].pTab) && IsVirtual(pTabList->a[ii].pTab) ){
      sWBI.pWC->vmask |= ((Bitmask)1 << ii);
    }
#endif
  }
#ifndef NDEBUG
  {
    Bitmask toTheLeft = 0;
    for(ii=0; ii<pTabList->nSrc; ii++){
      Bitmask m = getMask(pMaskSet, pTabList->a[ii].iCursor);
      assert( (m-1)==toTheLeft );
      toTheLeft |= m;
    }
  }
#endif

  /* Analyze all of the subexpressions.  Note that exprAnalyze() might
  ** add new virtual terms onto the end of the WHERE clause.  We do not
  ** 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, sWBI.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 && isDistinctRedundant(pParse, pTabList, sWBI.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[].iTabCur   The VDBE cursor for the database table
  **   pWInfo->a[].iIdxCur   The VDBE cursor for the index
  **   pWInfo->a[].pTerm     When wsFlags==WO_OR, the OR-clause term
  **
  ** This loop also figures out the nesting order of tables in the FROM
  ** clause.
  */
  sWBI.notValid = ~(Bitmask)0;
  sWBI.pOrderBy = pOrderBy;
  sWBI.n = nTabList;
  sWBI.pDistinct = pDistinct;
  andFlags = ~0;
  WHERETRACE(("*** Optimizer Start ***\n"));
  for(sWBI.i=iFrom=0, pLevel=pWInfo->a; sWBI.i<nTabList; sWBI.i++, pLevel++){
    WhereCost bestPlan;         /* Most efficient plan seen so far */
    Index *pIdx;                /* Index for FROM table at pTabItem */
    int j;                      /* For looping over FROM tables */
    int bestJ = -1;             /* The value of j */
    Bitmask m;                  /* Bitmask value for j or bestJ */
    int isOptimal;              /* Iterator for optimal/non-optimal search */
    int nUnconstrained;         /* Number tables without INDEXED BY */
    Bitmask notIndexed;         /* Mask of tables that cannot use an index */

    memset(&bestPlan, 0, sizeof(bestPlan));
    bestPlan.rCost = SQLITE_BIG_DBL;
    WHERETRACE(("*** Begin search for loop %d ***\n", sWBI.i));

    /* Loop through the remaining entries in the FROM clause to find the
    ** next nested loop. The loop tests all FROM clause entries
    ** either once or twice. 
    **
    ** The first test is always performed if there are two or more entries
    ** remaining and never performed if there is only one FROM clause entry
................................................................................
    ** this context an optimal scan is one that uses the same strategy
    ** for the given FROM clause entry as would be selected if the entry
    ** were used as the innermost nested loop.  In other words, a table
    ** is chosen such that the cost of running that table cannot be reduced
    ** by waiting for other tables to run first.  This "optimal" test works
    ** by first assuming that the FROM clause is on the inner loop and finding
    ** its query plan, then checking to see if that query plan uses any
    ** other FROM clause terms that are sWBI.notValid.  If no notValid terms
    ** are used then the "optimal" query plan works.
    **
    ** Note that the WhereCost.nRow parameter for an optimal scan might
    ** not be as small as it would be if the table really were the innermost
    ** join.  The nRow value can be reduced by WHERE clause constraints
    ** that do not use indices.  But this nRow reduction only happens if the
    ** table really is the innermost join.  
    **
................................................................................
    ** as the cost of a linear scan through table t1, a simple greedy 
    ** algorithm may choose to use t2 for the outer loop, which is a much
    ** costlier approach.
    */
    nUnconstrained = 0;
    notIndexed = 0;
    for(isOptimal=(iFrom<nTabList-1); isOptimal>=0 && bestJ<0; isOptimal--){

      for(j=iFrom, sWBI.pSrc=&pTabList->a[j]; j<nTabList; j++, sWBI.pSrc++){
        int doNotReorder;    /* True if this table should not be reordered */



  
        doNotReorder =  (sWBI.pSrc->jointype & (JT_LEFT|JT_CROSS))!=0;
        if( j!=iFrom && doNotReorder ) break;
        m = getMask(pMaskSet, sWBI.pSrc->iCursor);

        if( (m & sWBI.notValid)==0 ){
          if( j==iFrom ) iFrom++;
          continue;
        }
        sWBI.notReady = (isOptimal ? m : sWBI.notValid);


        if( sWBI.pSrc->pIndex==0 ) nUnconstrained++;
  
        WHERETRACE(("=== trying table %d with isOptimal=%d ===\n",
                    j, isOptimal));
        assert( sWBI.pSrc->pTab );
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(sWBI.pSrc->pTab) ){
          sWBI.ppIdxInfo = &pWInfo->a[j].pIdxInfo;
          bestVirtualIndex(&sWBI);

        }else 
#endif
        {
          bestBtreeIndex(&sWBI);

        }
        assert( isOptimal || (sWBI.cost.used&sWBI.notValid)==0 );

        /* If an INDEXED BY clause is present, then the plan must use that
        ** index if it uses any index at all */
        assert( sWBI.pSrc->pIndex==0 
                  || (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0
                  || sWBI.cost.plan.u.pIdx==sWBI.pSrc->pIndex );

        if( isOptimal && (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ){
          notIndexed |= m;
        }

        /* Conditions under which this table becomes the best so far:
        **
        **   (1) The table must not depend on other tables that have not
        **       yet run.  (In other words, it must not depend on tables
        **       in inner loops.)
        **
        **   (2) A full-table-scan plan cannot supercede indexed plan unless
        **       the full-table-scan is an "optimal" plan as defined above.
        **
        **   (3) All tables have an INDEXED BY clause or this table lacks an
        **       INDEXED BY clause or this table uses the specific
        **       index specified by its INDEXED BY clause.  This rule ensures
................................................................................
        **       will be detected and relayed back to the application later.
        **       The NEVER() comes about because rule (2) above prevents
        **       An indexable full-table-scan from reaching rule (3).
        **
        **   (4) The plan cost must be lower than prior plans or else the
        **       cost must be the same and the number of rows must be lower.
        */
        if( (sWBI.cost.used&sWBI.notValid)==0                    /* (1) */
            && (bestJ<0 || (notIndexed&m)!=0                     /* (2) */
                || (bestPlan.plan.wsFlags & WHERE_NOT_FULLSCAN)==0
                || (sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0)
            && (nUnconstrained==0 || sWBI.pSrc->pIndex==0        /* (3) */
                || NEVER((sWBI.cost.plan.wsFlags & WHERE_NOT_FULLSCAN)!=0))
            && (bestJ<0 || sWBI.cost.rCost<bestPlan.rCost        /* (4) */
                || (sWBI.cost.rCost<=bestPlan.rCost 
                 && sWBI.cost.plan.nRow<bestPlan.plan.nRow))
        ){
          WHERETRACE(("=== table %d is best so far"
                      " with cost=%.1f, nRow=%.1f, nOBSat=%d\n",
                      j, sWBI.cost.rCost, sWBI.cost.plan.nRow,
                      sWBI.cost.plan.nOBSat));
          bestPlan = sWBI.cost;
          bestJ = j;
        }
        if( doNotReorder ) break;
      }
    }
    assert( bestJ>=0 );
    assert( sWBI.notValid & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d with:\n"
                "    cost=%.1f, nRow=%.1f, nOBSat=%d wsFlags=0x%08x\n",
                bestJ, pLevel-pWInfo->a, bestPlan.rCost, bestPlan.plan.nRow,
                bestPlan.plan.nOBSat, bestPlan.plan.wsFlags));
    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
      pWInfo->nOBSat = pOrderBy->nExpr;
    }
    if( (bestPlan.plan.wsFlags & WHERE_DISTINCT)!=0 ){
      assert( pWInfo->eDistinct==0 );
      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
    }
................................................................................
        pLevel->iIdxCur = iIdxCur;
      }else{
        pLevel->iIdxCur = pParse->nTab++;
      }
    }else{
      pLevel->iIdxCur = -1;
    }
    sWBI.notValid &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor);
    pLevel->iFrom = (u8)bestJ;
    if( bestPlan.plan.nRow>=(double)1 ){
      pParse->nQueryLoop *= bestPlan.plan.nRow;
    }

    /* Check that if the table scanned by this loop iteration had an
    ** INDEXED BY clause attached to it, that the named index is being
................................................................................

  /* Open all tables in the pTabList and any indices selected for
  ** searching those tables.
  */
  sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
  notReady = ~(Bitmask)0;
  pWInfo->nRowOut = (double)1;
  for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
    Table *pTab;     /* Table to open */
    int iDb;         /* Index of database containing table/index */
    struct SrcList_item *pTabItem;

    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
    pLevel->iTabCur = pTabItem->iCursor;
    pWInfo->nRowOut *= pLevel->plan.nRow;
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
................................................................................
        assert( n<=pTab->nCol );
      }
    }else{
      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
    }
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->plan.wsFlags & WHERE_TEMP_INDEX)!=0 ){
      constructAutomaticIndex(pParse, sWBI.pWC, pTabItem, notReady, pLevel);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
      Index *pIx = pLevel->plan.u.pIdx;
      KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
      int iIndexCur = pLevel->iIdxCur;
      assert( pIx->pSchema==pTab->pSchema );
      assert( iIndexCur>=0 );
      sqlite3VdbeAddOp4(v, OP_OpenRead, iIndexCur, pIx->tnum, iDb,
                        (char*)pKey, P4_KEYINFO_HANDOFF);
      VdbeComment((v, "%s", pIx->zName));
    }
    sqlite3CodeVerifySchema(pParse, iDb);
    notReady &= ~getMask(sWBI.pWC->pMaskSet, pTabItem->iCursor);
  }
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* 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(ii=0; ii<nTabList; ii++){
    pLevel = &pWInfo->a[ii];
    explainOneScan(pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags);
    notReady = codeOneLoopStart(pWInfo, ii, wctrlFlags, notReady);
    pWInfo->iContinue = pLevel->addrCont;
  }

#ifdef SQLITE_TEST  /* For testing and debugging use only */
  /* Record in the query plan information about the current table
  ** and the index used to access it (if any).  If the table itself
  ** is not used, its name is just '{}'.  If no index is used
  ** the index is listed as "{}".  If the primary key is used the
  ** index name is '*'.
  */
  for(ii=0; ii<nTabList; ii++){
    char *z;
    int n;
    int w;
    struct SrcList_item *pTabItem;

    pLevel = &pWInfo->a[ii];
    w = pLevel->plan.wsFlags;
    pTabItem = &pTabList->a[pLevel->iFrom];
    z = pTabItem->zAlias;
    if( z==0 ) z = pTabItem->pTab->zName;
    n = sqlite3Strlen30(z);
    if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){
      if( (w & WHERE_IDX_ONLY)!=0 && (w & WHERE_COVER_SCAN)==0 ){

Changes to test/collate5.test.

217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
...
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
# These tests - collate5-3.* - focus on compound SELECT queries that 
# feature ORDER BY clauses.
#
do_test collate5-3.0 {
  execsql {
    SELECT a FROM collate5t1 UNION ALL SELECT a FROM collate5t2 ORDER BY 1;
  }
} {a A a A b B b B n N}
do_test collate5-3.1 {
  execsql {
    SELECT a FROM collate5t2 UNION ALL SELECT a FROM collate5t1 ORDER BY 1;
  }
} {A A B B N a a b b n}
do_test collate5-3.2 {
  execsql {
................................................................................
    SELECT a, count(*) FROM collate5t1 GROUP BY a;
  }]
} {a 2 b 2}
do_test collate5-4.2 {
  execsql {
    SELECT a, b, count(*) FROM collate5t1 GROUP BY a, b ORDER BY a, b;
  }
} {A 1.0 2 b 2 1 B 3 1}
do_test collate5-4.3 {
  execsql {
    DROP TABLE collate5t1;
  }
} {}

finish_test







|







 







|







217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
...
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
# These tests - collate5-3.* - focus on compound SELECT queries that 
# feature ORDER BY clauses.
#
do_test collate5-3.0 {
  execsql {
    SELECT a FROM collate5t1 UNION ALL SELECT a FROM collate5t2 ORDER BY 1;
  }
} {/[aA] [aA] [aA] [aA] [bB] [bB] [bB] [bB] [nN] [nN]/}
do_test collate5-3.1 {
  execsql {
    SELECT a FROM collate5t2 UNION ALL SELECT a FROM collate5t1 ORDER BY 1;
  }
} {A A B B N a a b b n}
do_test collate5-3.2 {
  execsql {
................................................................................
    SELECT a, count(*) FROM collate5t1 GROUP BY a;
  }]
} {a 2 b 2}
do_test collate5-4.2 {
  execsql {
    SELECT a, b, count(*) FROM collate5t1 GROUP BY a, b ORDER BY a, b;
  }
} {/[aA] 1(.0)? 2 [bB] 2 1 [bB] 3 1/}
do_test collate5-4.3 {
  execsql {
    DROP TABLE collate5t1;
  }
} {}

finish_test

Changes to test/e_select.test.

1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
....
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
....
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
....
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
#   These tests also show that the following is not untrue:
#
# EVIDENCE-OF: R-25883-55063 The expressions in the GROUP BY clause do
# not have to be expressions that appear in the result.
#
do_select_tests e_select-4.9 {
  1  "SELECT group_concat(one), two FROM b1 GROUP BY two" {
    4,5 f   1 o   7,6   s 3,2 t
  }
  2  "SELECT group_concat(one), sum(one) FROM b1 GROUP BY (one>4)" {
    1,2,3,4 10    5,6,7 18
  }
  3  "SELECT group_concat(one) FROM b1 GROUP BY (two>'o'), one%2" {
    4  1,5    2,6   3,7
  }
................................................................................
  }
}

# EVIDENCE-OF: R-14926-50129 For the purposes of grouping rows, NULL
# values are considered equal.
#
do_select_tests e_select-4.10 {
  1  "SELECT group_concat(y) FROM b2 GROUP BY x" {0,1   3   2,4}
  2  "SELECT count(*) FROM b2 GROUP BY CASE WHEN y<4 THEN NULL ELSE 0 END" {4 1}
} 

# EVIDENCE-OF: R-10470-30318 The usual rules for selecting a collation
# sequence with which to compare text values apply when evaluating
# expressions in a GROUP BY clause.
#
................................................................................
     1 2 3    1 2 -20    1 4  93    1 5 -1   
  }
  7  "SELECT * FROM d1 ORDER BY 1 DESC, 2, 3" {
     2 4 93   2 5 -1     1 2 -20    1 2 3    
     1 2 7    1 2 8      1 4  93    1 5 -1   
  }
  8  "SELECT z, x FROM d1 ORDER BY 2" {
     3 1     8 1    7 1   -20 1 
     93 1   -1 1   -1 2   93 2
  }
  9  "SELECT z, x FROM d1 ORDER BY 1" {
     -20 1  -1 2   -1 1   3 1     
     7 1     8 1   93 2   93 1   
  }
}

# EVIDENCE-OF: R-63286-51977 If the ORDER BY expression is an identifier
# that corresponds to the alias of one of the output columns, then the
# expression is considered an alias for that column.
#
................................................................................
  1   "SELECT z+1 AS abc FROM d1 ORDER BY abc" {
    -19 0 0 4 8 9 94 94
  }
  2   "SELECT z+1 AS abc FROM d1 ORDER BY abc DESC" {
    94 94 9 8 4 0 0 -19
  }
  3  "SELECT z AS x, x AS z FROM d1 ORDER BY z" {
    3 1    8 1    7 1    -20 1    93 1    -1 1    -1 2    93 2
  }
  4  "SELECT z AS x, x AS z FROM d1 ORDER BY x" {
    -20 1    -1 2    -1 1    3 1    7 1    8 1    93 2    93 1
  }
}

# EVIDENCE-OF: R-65068-27207 Otherwise, if the ORDER BY expression is
# any other expression, it is evaluated and the returned value used to
# order the output rows.
#







|







 







|







 







|
|


|
|







 







|


|







1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
....
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
....
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
....
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
#   These tests also show that the following is not untrue:
#
# EVIDENCE-OF: R-25883-55063 The expressions in the GROUP BY clause do
# not have to be expressions that appear in the result.
#
do_select_tests e_select-4.9 {
  1  "SELECT group_concat(one), two FROM b1 GROUP BY two" {
    /#,# f   1 o   #,#   s #,# t/
  }
  2  "SELECT group_concat(one), sum(one) FROM b1 GROUP BY (one>4)" {
    1,2,3,4 10    5,6,7 18
  }
  3  "SELECT group_concat(one) FROM b1 GROUP BY (two>'o'), one%2" {
    4  1,5    2,6   3,7
  }
................................................................................
  }
}

# EVIDENCE-OF: R-14926-50129 For the purposes of grouping rows, NULL
# values are considered equal.
#
do_select_tests e_select-4.10 {
  1  "SELECT group_concat(y) FROM b2 GROUP BY x" {/#,#   3   #,#/}
  2  "SELECT count(*) FROM b2 GROUP BY CASE WHEN y<4 THEN NULL ELSE 0 END" {4 1}
} 

# EVIDENCE-OF: R-10470-30318 The usual rules for selecting a collation
# sequence with which to compare text values apply when evaluating
# expressions in a GROUP BY clause.
#
................................................................................
     1 2 3    1 2 -20    1 4  93    1 5 -1   
  }
  7  "SELECT * FROM d1 ORDER BY 1 DESC, 2, 3" {
     2 4 93   2 5 -1     1 2 -20    1 2 3    
     1 2 7    1 2 8      1 4  93    1 5 -1   
  }
  8  "SELECT z, x FROM d1 ORDER BY 2" {
     /# 1    # 1    # 1   # 1 
      # 1    # 1    # 2   # 2/
  }
  9  "SELECT z, x FROM d1 ORDER BY 1" {
     /-20 1  -1 #   -1 #   3 1
     7 1     8 1   93 #   93 #/   
  }
}

# EVIDENCE-OF: R-63286-51977 If the ORDER BY expression is an identifier
# that corresponds to the alias of one of the output columns, then the
# expression is considered an alias for that column.
#
................................................................................
  1   "SELECT z+1 AS abc FROM d1 ORDER BY abc" {
    -19 0 0 4 8 9 94 94
  }
  2   "SELECT z+1 AS abc FROM d1 ORDER BY abc DESC" {
    94 94 9 8 4 0 0 -19
  }
  3  "SELECT z AS x, x AS z FROM d1 ORDER BY z" {
    /# 1    # 1    # 1    # 1    # 1    # 1    # 2    # 2/
  }
  4  "SELECT z AS x, x AS z FROM d1 ORDER BY x" {
    /-20 1    -1 #    -1 #    3 1    7 1    8 1    93 #    93 #/
  }
}

# EVIDENCE-OF: R-65068-27207 Otherwise, if the ORDER BY expression is
# any other expression, it is evaluated and the returned value used to
# order the output rows.
#

Added test/orderby1.test.





















































































































































































































































































































































































































































































































































































































































































































































































































































































>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
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
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
# 2012 Sept 27
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing that the optimizations that disable
# ORDER BY clauses when the natural order of a query is correct.
#


set testdir [file dirname $argv0]
source $testdir/tester.tcl
set ::testprefix orderby1

# Generate test data for a join.  Verify that the join gets the
# correct answer.
#
do_test 1.0 {
  db eval {
    BEGIN;
    CREATE TABLE album(
      aid INTEGER PRIMARY KEY,
      title TEXT UNIQUE NOT NULL
    );
    CREATE TABLE track(
      tid INTEGER PRIMARY KEY,
      aid INTEGER NOT NULL REFERENCES album,
      tn INTEGER NOT NULL,
      name TEXT,
      UNIQUE(aid, tn)
    );
    INSERT INTO album VALUES(1, '1-one'), (2, '2-two'), (3, '3-three');
    INSERT INTO track VALUES
        (NULL, 1, 1, 'one-a'),
        (NULL, 2, 2, 'two-b'),
        (NULL, 3, 3, 'three-c'),
        (NULL, 1, 3, 'one-c'),
        (NULL, 2, 1, 'two-a'),
        (NULL, 3, 1, 'three-a');
    COMMIT;
  }
} {}
do_test 1.1a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {one-a one-c two-a two-b three-a three-c}

# Verify that the ORDER BY clause is optimized out
#
do_test 1.1b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {~/ORDER BY/}  ;# ORDER BY optimized out

# The same query with ORDER BY clause optimization disabled via + operators
# should give exactly the same answer.
#
do_test 1.2a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn
  }
} {one-a one-c two-a two-b three-a three-c}

# The output is sorted manually in this case.
#
do_test 1.2b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn
  }
} {/ORDER BY/}   ;# separate sorting pass due to "+" on ORDER BY terms

# The same query with ORDER BY optimizations turned off via built-in test.
#
do_test 1.3a {
  optimization_control db order-by-idx-join 0
  db cache flush
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {one-a one-c two-a two-b three-a three-c}
do_test 1.3b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {/ORDER BY/}   ;# separate sorting pass due to disabled optimization
optimization_control db all 1
db cache flush

# Reverse order sorts
#
do_test 1.4a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {three-a three-c two-a two-b one-a one-c}
do_test 1.4b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn
  }
} {three-a three-c two-a two-b one-a one-c}  ;# verify same order after sorting
do_test 1.4c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {/ORDER BY/}  ;# separate sorting pass due to mixed DESC/ASC


do_test 1.5a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}
do_test 1.5b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}  ;# verify same order after sorting
do_test 1.5c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {/ORDER BY/}  ;# separate sorting pass due to mixed DESC/ASC

do_test 1.6a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}
do_test 1.6b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}  ;# verify same order after sorting
do_test 1.6c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {~/ORDER BY/}  ;# ORDER BY optimized-out


# Reconstruct the test data to use indices rather than integer primary keys.
#
do_test 2.0 {
  db eval {
    BEGIN;
    DROP TABLE album;
    DROP TABLE track;
    CREATE TABLE album(
      aid INT PRIMARY KEY,
      title TEXT NOT NULL
    );
    CREATE INDEX album_i1 ON album(title, aid);
    CREATE TABLE track(
      aid INTEGER NOT NULL REFERENCES album,
      tn INTEGER NOT NULL,
      name TEXT,
      UNIQUE(aid, tn)
    );
    INSERT INTO album VALUES(1, '1-one'), (2, '2-two'), (3, '3-three');
    INSERT INTO track VALUES
        (1, 1, 'one-a'),
        (2, 2, 'two-b'),
        (3, 3, 'three-c'),
        (1, 3, 'one-c'),
        (2, 1, 'two-a'),
        (3, 1, 'three-a');
    COMMIT;
  }
} {}
do_test 2.1a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {one-a one-c two-a two-b three-a three-c}

# Verify that the ORDER BY clause is optimized out
#
do_test 2.1b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {~/ORDER BY/}  ;# ORDER BY optimized out

# The same query with ORDER BY clause optimization disabled via + operators
# should give exactly the same answer.
#
do_test 2.2a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn
  }
} {one-a one-c two-a two-b three-a three-c}

# The output is sorted manually in this case.
#
do_test 2.2b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn
  }
} {/ORDER BY/}   ;# separate sorting pass due to "+" on ORDER BY terms

# The same query with ORDER BY optimizations turned off via built-in test.
#
do_test 2.3a {
  optimization_control db order-by-idx-join 0
  db cache flush
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {one-a one-c two-a two-b three-a three-c}
do_test 2.3b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {/ORDER BY/}   ;# separate sorting pass due to disabled optimization
optimization_control db all 1
db cache flush

# Reverse order sorts
#
do_test 2.4a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {three-a three-c two-a two-b one-a one-c}
do_test 2.4b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn
  }
} {three-a three-c two-a two-b one-a one-c}  ;# verify same order after sorting
do_test 2.4c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {/ORDER BY/}  ;# separate sorting pass due to mixed DESC/ASC


do_test 2.5a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}
do_test 2.5b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}  ;# verify same order after sorting
do_test 2.5c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {/ORDER BY/}  ;# separate sorting pass due to mixed ASC/DESC

do_test 2.6a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}
do_test 2.6b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}  ;# verify same order after sorting
do_test 2.6c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {~/ORDER BY/}  ;# ORDER BY optimized-out


# Generate another test dataset, but this time using mixed ASC/DESC indices.
#
do_test 3.0 {
  db eval {
    BEGIN;
    DROP TABLE album;
    DROP TABLE track;
    CREATE TABLE album(
      aid INTEGER PRIMARY KEY,
      title TEXT UNIQUE NOT NULL
    );
    CREATE TABLE track(
      tid INTEGER PRIMARY KEY,
      aid INTEGER NOT NULL REFERENCES album,
      tn INTEGER NOT NULL,
      name TEXT,
      UNIQUE(aid ASC, tn DESC)
    );
    INSERT INTO album VALUES(1, '1-one'), (2, '2-two'), (3, '3-three');
    INSERT INTO track VALUES
        (NULL, 1, 1, 'one-a'),
        (NULL, 2, 2, 'two-b'),
        (NULL, 3, 3, 'three-c'),
        (NULL, 1, 3, 'one-c'),
        (NULL, 2, 1, 'two-a'),
        (NULL, 3, 1, 'three-a');
    COMMIT;
  }
} {}
do_test 3.1a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}

# Verify that the ORDER BY clause is optimized out
#
do_test 3.1b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {~/ORDER BY/}  ;# ORDER BY optimized out

# The same query with ORDER BY clause optimization disabled via + operators
# should give exactly the same answer.
#
do_test 3.2a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}

# The output is sorted manually in this case.
#
do_test 3.2b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn DESC
  }
} {/ORDER BY/}   ;# separate sorting pass due to "+" on ORDER BY terms

# The same query with ORDER BY optimizations turned off via built-in test.
#
do_test 3.3a {
  optimization_control db order-by-idx-join 0
  db cache flush
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {one-c one-a two-b two-a three-c three-a}
do_test 3.3b {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn DESC
  }
} {/ORDER BY/}   ;# separate sorting pass due to disabled optimization
optimization_control db all 1
db cache flush

# Without the mixed ASC/DESC on ORDER BY
#
do_test 3.4a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {one-a one-c two-a two-b three-a three-c}
do_test 3.4b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title, +tn
  }
} {one-a one-c two-a two-b three-a three-c}  ;# verify same order after sorting
do_test 3.4c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title, tn
  }
} {/ORDER BY/}  ;# separate sorting pass due to mismatched DESC/ASC


do_test 3.5a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}
do_test 3.5b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn DESC
  }
} {three-c three-a two-b two-a one-c one-a}  ;# verify same order after sorting
do_test 3.5c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn DESC
  }
} {/ORDER BY/}  ;# separate sorting pass due to mismatched ASC/DESC


do_test 3.6a {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {three-a three-c two-a two-b one-a one-c}
do_test 3.6b {
  db eval {
    SELECT name FROM album JOIN track USING (aid) ORDER BY +title DESC, +tn
  }
} {three-a three-c two-a two-b one-a one-c}  ;# verify same order after sorting
do_test 3.6c {
  db eval {
    EXPLAIN QUERY PLAN
    SELECT name FROM album JOIN track USING (aid) ORDER BY title DESC, tn
  }
} {~/ORDER BY/}  ;# inverted ASC/DESC is optimized out


finish_test

Changes to test/tester.tcl.

534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
  if {![info exists ::G(match)] || [string match $::G(match) $name]} {
    if {[catch {uplevel #0 "$cmd;\n"} result]} {
      puts "\nError: $result"
      fail_test $name
    } else {
      if {[regexp {^~?/.*/$} $expected]} {
        if {[string index $expected 0]=="~"} {
          set re [string range $expected 2 end-1]
          set ok [expr {![regexp $re $result]}]
        } else {
          set re [string range $expected 1 end-1]
          set ok [regexp $re $result]
        }
      } else {
        set ok [expr {[string compare $result $expected]==0}]
      }
      if {!$ok} {
        # if {![info exists ::testprefix] || $::testprefix eq ""} {







|


|







534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
  if {![info exists ::G(match)] || [string match $::G(match) $name]} {
    if {[catch {uplevel #0 "$cmd;\n"} result]} {
      puts "\nError: $result"
      fail_test $name
    } else {
      if {[regexp {^~?/.*/$} $expected]} {
        if {[string index $expected 0]=="~"} {
          set re [string map {# {[-0-9.]+}} [string range $expected 2 end-1]]
          set ok [expr {![regexp $re $result]}]
        } else {
          set re [string map {# {[-0-9.]+}} [string range $expected 1 end-1]]
          set ok [regexp $re $result]
        }
      } else {
        set ok [expr {[string compare $result $expected]==0}]
      }
      if {!$ok} {
        # if {![info exists ::testprefix] || $::testprefix eq ""} {

Changes to test/tkt-cbd054fa6b.test.

46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
..
78
79
80
81
82
83
84
85
86
87
do_test tkt-cbd05-1.3 {
  execsql { 
    SELECT tbl,idx,group_concat(sample,' ') 
    FROM sqlite_stat3 
    WHERE idx = 't1_x' 
    GROUP BY tbl,idx
  }
} {t1 t1_x { A B C D E F G H I}}

do_test tkt-cbd05-2.1 {
  db eval {
    DROP TABLE t1;
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB UNIQUE NOT NULL);
    CREATE INDEX t1_x ON t1(b);
    INSERT INTO t1 VALUES(NULL, X'');
................................................................................
do_test tkt-cbd05-2.3 {
  execsql { 
    SELECT tbl,idx,group_concat(sample,' ') 
    FROM sqlite_stat3 
    WHERE idx = 't1_x' 
    GROUP BY tbl,idx
  }
} {t1 t1_x { A B C D E F G H I}}

finish_test







|







 







|


46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
..
78
79
80
81
82
83
84
85
86
87
do_test tkt-cbd05-1.3 {
  execsql { 
    SELECT tbl,idx,group_concat(sample,' ') 
    FROM sqlite_stat3 
    WHERE idx = 't1_x' 
    GROUP BY tbl,idx
  }
} {/t1 t1_x .[ ABCDEFGHI]{10}./}

do_test tkt-cbd05-2.1 {
  db eval {
    DROP TABLE t1;
    CREATE TABLE t1(a INTEGER PRIMARY KEY, b BLOB UNIQUE NOT NULL);
    CREATE INDEX t1_x ON t1(b);
    INSERT INTO t1 VALUES(NULL, X'');
................................................................................
do_test tkt-cbd05-2.3 {
  execsql { 
    SELECT tbl,idx,group_concat(sample,' ') 
    FROM sqlite_stat3 
    WHERE idx = 't1_x' 
    GROUP BY tbl,idx
  }
} {/t1 t1_x .[ ABCDEFGHI]{10}./}

finish_test

Changes to test/where.test.

1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
  } 
} {1/4 1/1 4/4 4/1 nosort}
do_test where-14.5 {
  # This test case changed from "nosort" to "sort". See ticket 2a5629202f.
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, x.a||x.b
  } 
} {4/4 4/1 1/4 1/1 sort}
do_test where-14.6 {
  # This test case changed from "nosort" to "sort". See ticket 2a5629202f.
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, x.a||x.b DESC
  } 
} {4/4 4/1 1/4 1/1 sort}
do_test where-14.7 {
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, y.a||y.b
  } 
} {4/1 4/4 1/1 1/4 sort}
do_test where-14.7.1 {
  cksort {







|





|







1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
  } 
} {1/4 1/1 4/4 4/1 nosort}
do_test where-14.5 {
  # This test case changed from "nosort" to "sort". See ticket 2a5629202f.
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, x.a||x.b
  } 
} {/4/[14] 4/[14] 1/[14] 1/[14] sort/}
do_test where-14.6 {
  # This test case changed from "nosort" to "sort". See ticket 2a5629202f.
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, x.a||x.b DESC
  } 
} {/4/[14] 4/[14] 1/[14] 1/[14] sort/}
do_test where-14.7 {
  cksort {
    SELECT x.a || '/' || y.a FROM t8 x, t8 y ORDER BY x.b, y.a||y.b
  } 
} {4/1 4/4 1/1 1/4 sort}
do_test where-14.7.1 {
  cksort {