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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 3107 nRow = (double)(aiRowEst[nEq] * nInMul); 3108 3108 if( bInEst && nRow*2>aiRowEst[0] ){ 3109 3109 nRow = aiRowEst[0]/2; 3110 3110 nInMul = (int)(nRow / aiRowEst[nEq]); 3111 3111 } 3112 3112 3113 3113 #ifdef SQLITE_ENABLE_STAT2 3114 - /* If the constraint is of the form x=VALUE and histogram 3114 + /* If the constraint is of the form x=VALUE or x IN (E1,E2,...) 3115 + ** and we do not think that values of x are unique and if histogram 3115 3116 ** data is available for column x, then it might be possible 3116 3117 ** to get a better estimate on the number of rows based on 3117 3118 ** VALUE and how common that value is according to the histogram. 3118 3119 */ 3119 - if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 ){ 3120 + if( nRow>(double)1 && nEq==1 && pFirstTerm!=0 && aiRowEst[1]>1 ){ 3120 3121 if( pFirstTerm->eOperator & (WO_EQ|WO_ISNULL) ){ 3121 3122 testcase( pFirstTerm->eOperator==WO_EQ ); 3122 3123 testcase( pFirstTerm->eOperator==WO_ISNULL ); 3123 3124 whereEqualScanEst(pParse, pProbe, pFirstTerm->pExpr->pRight, &nRow); 3124 3125 }else if( pFirstTerm->eOperator==WO_IN && bInEst==0 ){ 3125 3126 whereInScanEst(pParse, pProbe, pFirstTerm->pExpr->x.pList, &nRow); 3126 3127 }