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Overview
Comment: | Improved presentation on the new code that prevents unnecessary writes to expressions on indexes during an UPDATE when the expression does not reference any of the columns that are changing. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
c9f045295c4577752b0847ff2027b446 |
User & Date: | drh 2018-09-16 15:01:25.994 |
Context
2018-09-16
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16:18 | Add the new "explain" virtual table in ext/misc. Use this virtual table for additional test cases for the optimization that avoids updating indexes on expressions when none of the columns changed by the UPDATE are in the expression. (check-in: 2404304cc1 user: drh tags: trunk) | |
15:01 | Improved presentation on the new code that prevents unnecessary writes to expressions on indexes during an UPDATE when the expression does not reference any of the columns that are changing. (check-in: c9f045295c user: drh tags: trunk) | |
2018-09-15
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21:43 | Increase the version number to 3.26.0 as we start the next development cycle. (check-in: 885f0f8252 user: drh tags: trunk) | |
Changes
Changes to src/update.c.
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80 81 82 83 84 85 86 | } /* ** Check to see if column iCol of index pIdx references any of the ** columns defined by aXRef and chngRowid. Return true if it does ** and false if not. ** | < < | | | > > > > > > | 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 | } /* ** Check to see if column iCol of index pIdx references any of the ** columns defined by aXRef and chngRowid. Return true if it does ** and false if not. ** ** aXRef[j] will be non-negative if column j of the original table is ** being updated. chngRowid will be true if the rowid of the table is ** being updated. */ static int indexColumnIsBeingUpdated( Index *pIdx, /* The index to check */ int iCol, /* Which column of the index to check */ int *aXRef, /* aXRef[j]>=0 if column j is being updated */ int chngRowid /* true if the rowid is being updated */ ){ i16 iIdxCol = pIdx->aiColumn[iCol]; if( iIdxCol>=0 ){ return aXRef[iIdxCol]>=0; } if( iIdxCol==XN_ROWID ) return 1; assert( iIdxCol==XN_EXPR ); assert( pIdx->aColExpr!=0 ); assert( pIdx->aColExpr->a[iCol].pExpr!=0 ); return sqlite3ExprReferencesUpdatedColumn(pIdx->aColExpr->a[iCol].pExpr, aXRef,chngRowid); } /* |
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330 331 332 333 334 335 336 | int reg; if( chngKey || hasFK>1 || pIdx->pPartIdxWhere || pIdx==pPk ){ reg = ++pParse->nMem; pParse->nMem += pIdx->nColumn; }else{ reg = 0; for(i=0; i<pIdx->nKeyCol; i++){ | < < < < | < | 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 | int reg; if( chngKey || hasFK>1 || pIdx->pPartIdxWhere || pIdx==pPk ){ reg = ++pParse->nMem; pParse->nMem += pIdx->nColumn; }else{ reg = 0; for(i=0; i<pIdx->nKeyCol; i++){ if( indexColumnIsBeingUpdated(pIdx, i, aXRef, chngRowid) ){ reg = ++pParse->nMem; pParse->nMem += pIdx->nColumn; if( (onError==OE_Replace) || (onError==OE_Default && pIdx->onError==OE_Replace) ){ bReplace = 1; } |
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