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Overview
| Comment: | Do not try to use STAT2 to refine the row estimate of a query that uses a unique or nearly-unique index. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
efffc49baf38698ed3de05d16b4261bf |
| User & Date: | drh 2011-07-13 18:31:10 |
Context
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2011-07-15
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| 13:43 | In os_unix.c, check if the ESTALE macro is defined before using it. check-in: 87017410 user: dan tags: trunk | |
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2011-07-13
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| 18:31 | Do not try to use STAT2 to refine the row estimate of a query that uses a unique or nearly-unique index. check-in: efffc49b user: drh tags: trunk | |
| 16:03 | Added the SQLITE_FCNTL_WIN32_AV_RETRY file control for configuring the retry counts and delays in the windows VFS. check-in: 7aaf0a6a user: drh tags: trunk | |
Changes
Changes to src/where.c.
3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 |
nRow = (double)(aiRowEst[nEq] * nInMul);
if( bInEst && nRow*2>aiRowEst[0] ){
nRow = aiRowEst[0]/2;
nInMul = (int)(nRow / aiRowEst[nEq]);
}
#ifdef SQLITE_ENABLE_STAT2
/* If the constraint is of the form x=VALUE and histogram
** data is available for column x, then it might be possible
** to get a better estimate on the number of rows based on
** VALUE and how common that value is according to the histogram.
*/
if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 ){
if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){
testcase( pFirstTerm->eOperator==WO_EQ );
testcase( pFirstTerm->eOperator==WO_ISNULL );
whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow);
}else if( pFirstTerm->eOperator==WO_IN && bInEst==0 ){
whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow);
}
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| > | |
3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 |
nRow = (double)(aiRowEst[nEq] * nInMul);
if( bInEst && nRow*2>aiRowEst[0] ){
nRow = aiRowEst[0]/2;
nInMul = (int)(nRow / aiRowEst[nEq]);
}
#ifdef SQLITE_ENABLE_STAT2
/* If the constraint is of the form x=VALUE or x IN (E1,E2,...)
** and we do not think that values of x are unique and if histogram
** data is available for column x, then it might be possible
** to get a better estimate on the number of rows based on
** VALUE and how common that value is according to the histogram.
*/
if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 && aiRowEst[1]>1 ){
if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){
testcase( pFirstTerm->eOperator==WO_EQ );
testcase( pFirstTerm->eOperator==WO_ISNULL );
whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow);
}else if( pFirstTerm->eOperator==WO_IN && bInEst==0 ){
whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow);
}
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