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Fix the handling of sub-queries with LIMIT clauses by the optimization

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activated by compile-time symbol SQLITE_COUNTOFVIEW_OPTIMIZATION.

FossilOrigin-Name: 21235d9a41567897418aa12f7bd6dd8d6ee363147527e1d8fbca14fc83e0f2c9
This commit is contained in:
dan
2018-08-03 20:19:52 +00:00
parent e4fe6d4e62
commit a4b5fb55f3
4 changed files with 65 additions and 18 deletions
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22
src/select.c
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@@ -5495,6 +5495,7 @@ static struct SrcList_item *isSelfJoinView(
** The transformation only works if all of the following are true:
**
** * The subquery is a UNION ALL of two or more terms
** * The subquery does not have a LIMIT clause
** * There is no WHERE or GROUP BY or HAVING clauses on the subqueries
** * The outer query is a simple count(*)
**
@@ -5518,6 +5519,7 @@ static int countOfViewOptimization(Parse *pParse, Select *p){
do{
if( pSub->op!=TK_ALL && pSub->pPrior ) return 0; /* Must be UNION ALL */
if( pSub->pWhere ) return 0; /* No WHERE clause */
if( pSub->pLimit ) return 0; /* No LIMIT clause */
if( pSub->selFlags & SF_Aggregate ) return 0; /* Not an aggregate */
pSub = pSub->pPrior; /* Repeat over compound */
}while( pSub );
@@ -5779,6 +5781,16 @@ int sqlite3Select(
SELECTTRACE(0x100,pParse,p,("Constant propagation not helpful\n"));
}
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
if( OptimizationEnabled(db, SQLITE_QueryFlattener|SQLITE_CountOfView)
&& countOfViewOptimization(pParse, p)
){
if( db->mallocFailed ) goto select_end;
pEList = p->pEList;
pTabList = p->pSrc;
}
#endif
/* For each term in the FROM clause, do two things:
** (1) Authorized unreferenced tables
** (2) Generate code for all sub-queries
@@ -5957,16 +5969,6 @@ int sqlite3Select(
}
#endif
#ifdef SQLITE_COUNTOFVIEW_OPTIMIZATION
if( OptimizationEnabled(db, SQLITE_QueryFlattener|SQLITE_CountOfView)
&& countOfViewOptimization(pParse, p)
){
if( db->mallocFailed ) goto select_end;
pEList = p->pEList;
pTabList = p->pSrc;
}
#endif
/* If the query is DISTINCT with an ORDER BY but is not an aggregate, and
** if the select-list is the same as the ORDER BY list, then this query
** can be rewritten as a GROUP BY. In other words, this: