SQLite: Check-in [8a42e236]

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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 \| SQL archive
Timelines:	family \| ancestors \| descendants \| both \| trunk
Files:	files \| file ages \| folders
SHA1:	8a42e236701c8afd9ada7d4568712a21690ea087
User & Date:	drh 2011-04-09 03:20:59

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: b9dbd993 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: 8a42e236 user: drh tags: trunk)
03:04		Back out the SQLITE_OMIT_UNIQUE_ENFORCEMENT compile-option. It is an unneeded complication. (check-in: 927e955b 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: 3b964155 user: drh tags: unordered-index-hack)

Changes

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Changes to src/analyze.c.

      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.








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      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.

  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 */
};

  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.

#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;
................................................................................

    /* 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;

#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;
................................................................................

    /* 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;