diff options
Diffstat (limited to 'src/select.c')
| -rw-r--r-- | src/select.c | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/src/select.c b/src/select.c index 3da69943f..a13abe375 100644 --- a/src/select.c +++ b/src/select.c @@ -4540,6 +4540,10 @@ static int propagateConstants( ** changes to the WHERE clause of the inner query could change the ** window over which window functions are calculated). ** +** (7) The inner query is a Common Table Expression (CTE) that should +** be materialized. (This restriction is implemented in the calling +** routine.) +** ** Return 0 if no changes are made and non-zero if one or more WHERE clause ** terms are duplicated into the subquery. */ @@ -4923,6 +4927,7 @@ static int resolveFromTermToCte( int bMayRecursive; /* True if compound joined by UNION [ALL] */ With *pSavedWith; /* Initial value of pParse->pWith */ int iRecTab = -1; /* Cursor for recursive table */ + CteUse *pCteUse; /* If pCte->zCteErr is non-NULL at this point, then this is an illegal ** recursive reference to CTE pCte. Leave an error in pParse and return @@ -4937,14 +4942,16 @@ static int resolveFromTermToCte( assert( pFrom->pTab==0 ); pTab = sqlite3DbMallocZero(db, sizeof(Table)); if( pTab==0 ) return 2; - if( pCte->pUse==0 ){ - pCte->pUse = sqlite3DbMallocZero(db, sizeof(pCte->pUse[0])); - if( pCte->pUse==0 - || sqlite3ParserAddCleanup(pParse,sqlite3DbFree,pCte->pUse)==0 + pCteUse = pCte->pUse; + if( pCteUse==0 ){ + pCte->pUse = pCteUse = sqlite3DbMallocZero(db, sizeof(pCteUse[0])); + if( pCteUse==0 + || sqlite3ParserAddCleanup(pParse,sqlite3DbFree,pCteUse)==0 ){ sqlite3DbFree(db, pTab); return 2; } + pCteUse->eM10d = pCte->eM10d; } pFrom->pTab = pTab; pTab->nTabRef = 1; @@ -4956,8 +4963,11 @@ static int resolveFromTermToCte( if( db->mallocFailed ) return 2; assert( pFrom->pSelect ); pFrom->fg.isCte = 1; - pFrom->u2.pCteUse = pCte->pUse; - pCte->pUse->nUse++; + pFrom->u2.pCteUse = pCteUse; + pCteUse->nUse++; + if( pCteUse->nUse>=2 && pCteUse->eM10d==M10d_Any ){ + pCteUse->eM10d = M10d_Yes; + } /* Check if this is a recursive CTE. */ pRecTerm = pSel = pFrom->pSelect; @@ -6226,7 +6236,7 @@ int sqlite3Select( ** inside the subquery. This can help the subquery to run more efficiently. */ if( OptimizationEnabled(db, SQLITE_PushDown) - && (pItem->fg.isCte==0 || pItem->u2.pCteUse->nUse<=1) + && (pItem->fg.isCte==0 || pItem->u2.pCteUse->eM10d==M10d_Yes) && pushDownWhereTerms(pParse, pSub, p->pWhere, pItem->iCursor, (pItem->fg.jointype & JT_OUTER)!=0) ){ @@ -6250,7 +6260,7 @@ int sqlite3Select( ** The subquery is implemented as a co-routine if: ** (1) the subquery is guaranteed to be the outer loop (so that ** it does not need to be computed more than once), and - ** (2) the subquery is not a CTE that is used more then once. + ** (2) the subquery is not a CTE that should be materialized ** ** TODO: Are there other reasons beside (1) and (2) to use a co-routine ** implementation? @@ -6258,7 +6268,7 @@ int sqlite3Select( if( i==0 && (pTabList->nSrc==1 || (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0) /* (1) */ - && (pItem->fg.isCte==0 || pItem->u2.pCteUse->nUse<2) /* (2) */ + && (pItem->fg.isCte==0 || pItem->u2.pCteUse->eM10d!=M10d_Yes) /* (2) */ ){ /* Implement a co-routine that will return a single row of the result ** set on each invocation. |