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The optimization of check-in [9b2879629c34fc0a] is incorrectly reasoned.

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The WHERE clause of the partial index might not be true if the table of
the partial index is the right table of a left join.  So disable the
optimization in that case.  Ticket [623eff57e76d45f6]

FossilOrigin-Name: 3be19e1151af1850b65991edb82420f9412a7798dd756c86eaa9ffdde573263a
This commit is contained in:
drh
2019-11-03 00:07:41 +00:00
parent 0383661414
commit db535390db
4 changed files with 62 additions and 36 deletions
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64
src/wherecode.c
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@@ -1870,35 +1870,43 @@ Bitmask sqlite3WhereCodeOneLoopStart(
iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
}
/* If pIdx is an index on one or more expressions, then look through
** all the expressions in pWInfo and try to transform matching expressions
** into reference to index columns. Also attempt to translate references
** to virtual columns in the table into references to (stored) columns
** of the index.
**
** Do not do this for the RHS of a LEFT JOIN. This is because the
** expression may be evaluated after OP_NullRow has been executed on
** the cursor. In this case it is important to do the full evaluation,
** as the result of the expression may not be NULL, even if all table
** column values are. https://www.sqlite.org/src/info/7fa8049685b50b5a
**
** Also, do not do this when processing one index an a multi-index
** OR clause, since the transformation will become invalid once we
** move forward to the next index.
** https://sqlite.org/src/info/4e8e4857d32d401f
*/
if( pLevel->iLeftJoin==0 && (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0 ){
whereIndexExprTrans(pIdx, iCur, iIdxCur, pWInfo);
if( pLevel->iLeftJoin==0 ){
/* If pIdx is an index on one or more expressions, then look through
** all the expressions in pWInfo and try to transform matching expressions
** into reference to index columns. Also attempt to translate references
** to virtual columns in the table into references to (stored) columns
** of the index.
**
** Do not do this for the RHS of a LEFT JOIN. This is because the
** expression may be evaluated after OP_NullRow has been executed on
** the cursor. In this case it is important to do the full evaluation,
** as the result of the expression may not be NULL, even if all table
** column values are. https://www.sqlite.org/src/info/7fa8049685b50b5a
**
** Also, do not do this when processing one index an a multi-index
** OR clause, since the transformation will become invalid once we
** move forward to the next index.
** https://sqlite.org/src/info/4e8e4857d32d401f
*/
if( (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0 ){
whereIndexExprTrans(pIdx, iCur, iIdxCur, pWInfo);
}
/* If a partial index is driving the loop, try to eliminate WHERE clause
** terms from the query that must be true due to the WHERE clause of
** the partial index.
**
** 2019-11-02 ticket 623eff57e76d45f6: This optimization does not work
** for a LEFT JOIN.
*/
if( pIdx->pPartIdxWhere ){
whereApplyPartialIndexConstraints(pIdx->pPartIdxWhere, iCur, pWC);
}
}else{
testcase( (pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE)==0 );
testcase( pIdx->pPartIdxWhere );
}
/* If a partial index is driving the loop, try to eliminate WHERE clause
** terms from the query that must be true due to the WHERE clause of
** the partial index
*/
if( pIdx->pPartIdxWhere ){
whereApplyPartialIndexConstraints(pIdx->pPartIdxWhere, iCur, pWC);
}
/* Record the instruction used to terminate the loop. */
if( pLoop->wsFlags & WHERE_ONEROW ){
pLevel->op = OP_Noop;