SQLite

Check-in [8a42e23670]
Login

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

Overview
Comment:If the keyword "unordered" appears at the end of the SQLITE_STAT1.STAT column for an index, then use that index for equality lookups only, never for range queries or sorting. This feature is currently undocumented and my change or be removed in a future release.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 8a42e236701c8afd9ada7d4568712a21690ea087
User & Date: drh 2011-04-09 03:20:59.281
Context
2011-04-09
15:39
Add an OP_VerifyCookie instruction to "CREATE XXX IF NOT EXISTS" commands. This way, if the specified database object existed when the statement was compiled but removed from the database before sqlite3_step() was called, the statement still works as expected (and creates the object). (check-in: b9dbd99361 user: dan tags: trunk)
03:20
If the keyword "unordered" appears at the end of the SQLITE_STAT1.STAT column for an index, then use that index for equality lookups only, never for range queries or sorting. This feature is currently undocumented and my change or be removed in a future release. (check-in: 8a42e23670 user: drh tags: trunk)
03:04
Back out the SQLITE_OMIT_UNIQUE_ENFORCEMENT compile-option. It is an unneeded complication. (check-in: 927e955b93 user: drh tags: trunk)
2011-03-29
15:00
If the keyword "unordered" appears at the end of the SQLITE_STAT1.STAT column for an index, then use that index for equality lookups only, never for range queries or sorting. (Closed-Leaf check-in: 3b964155f6 user: drh tags: unordered-index-hack)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/analyze.c.
544
545
546
547
548
549
550




551
552
553
554
555
556
557
      v = v*10 + c - '0';
      z++;
    }
    if( i==0 ) pTable->nRowEst = v;
    if( pIndex==0 ) break;
    pIndex->aiRowEst[i] = v;
    if( *z==' ' ) z++;




  }
  return 0;
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.







>
>
>
>







544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
      v = v*10 + c - '0';
      z++;
    }
    if( i==0 ) pTable->nRowEst = v;
    if( pIndex==0 ) break;
    pIndex->aiRowEst[i] = v;
    if( *z==' ' ) z++;
    if( memcmp(z, "unordered", 10)==0 ){
      pIndex->bUnordered = 1;
      break;
    }
  }
  return 0;
}

/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.
Changes to src/sqliteInt.h.
1472
1473
1474
1475
1476
1477
1478

1479
1480
1481
1482
1483
1484
1485
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */

  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
};







>







1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
  int nColumn;     /* Number of columns in the table used by this index */
  int *aiColumn;   /* Which columns are used by this index.  1st is 0 */
  unsigned *aiRowEst; /* Result of ANALYZE: Est. rows selected by each column */
  Table *pTable;   /* The SQL table being indexed */
  int tnum;        /* Page containing root of this index in database file */
  u8 onError;      /* OE_Abort, OE_Ignore, OE_Replace, or OE_None */
  u8 autoIndex;    /* True if is automatically created (ex: by UNIQUE) */
  u8 bUnordered;   /* Use this index for == or IN queries only */
  char *zColAff;   /* String defining the affinity of each column */
  Index *pNext;    /* The next index associated with the same table */
  Schema *pSchema; /* Schema containing this index */
  u8 *aSortOrder;  /* Array of size Index.nColumn. True==DESC, False==ASC */
  char **azColl;   /* Array of collation sequence names for index */
  IndexSample *aSample;    /* Array of SQLITE_INDEX_SAMPLES samples */
};
Changes to src/where.c.
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
#ifdef SQLITE_ENABLE_STAT2
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }

    /* Determine the value of estBound. */
    if( nEq<pProbe->nColumn ){
      int j = 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, &estBound);
        if( pTop ){
          nBound = 1;







|







2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
#ifdef SQLITE_ENABLE_STAT2
      if( nEq==0 && pProbe->aSample ) pFirstTerm = pTerm;
#endif
      used |= pTerm->prereqRight;
    }

    /* Determine the value of estBound. */
    if( nEq<pProbe->nColumn && pProbe->bUnordered==0 ){
      int j = 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, &estBound);
        if( pTop ){
          nBound = 1;
2891
2892
2893
2894
2895
2896
2897

2898
2899
2900
2901
2902
2903
2904

    /* If there is an ORDER BY clause and the index being considered will
    ** naturally scan rows in the required order, set the appropriate flags
    ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
    ** will scan rows in a different order, set the bSort variable.  */
    if( pOrderBy ){
      if( (wsFlags & WHERE_COLUMN_IN)==0

        && isSortingIndex(pParse, pWC->pMaskSet, pProbe, iCur, pOrderBy,
                          nEq, wsFlags, &rev)
      ){
        wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
        wsFlags |= (rev ? WHERE_REVERSE : 0);
      }else{
        bSort = 1;







>







2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905

    /* If there is an ORDER BY clause and the index being considered will
    ** naturally scan rows in the required order, set the appropriate flags
    ** in wsFlags. Otherwise, if there is an ORDER BY clause but the index
    ** will scan rows in a different order, set the bSort variable.  */
    if( pOrderBy ){
      if( (wsFlags & WHERE_COLUMN_IN)==0
        && pProbe->bUnordered==0
        && isSortingIndex(pParse, pWC->pMaskSet, pProbe, iCur, pOrderBy,
                          nEq, wsFlags, &rev)
      ){
        wsFlags |= WHERE_ROWID_RANGE|WHERE_COLUMN_RANGE|WHERE_ORDERBY;
        wsFlags |= (rev ? WHERE_REVERSE : 0);
      }else{
        bSort = 1;