diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/select.c | 45 |
1 files changed, 25 insertions, 20 deletions
diff --git a/src/select.c b/src/select.c index 827bfb7cf..c097d23e4 100644 --- a/src/select.c +++ b/src/select.c @@ -6713,8 +6713,8 @@ static SrcItem *isSelfJoinView( assert( pThis->pSelect!=0 ); if( pThis->pSelect->selFlags & SF_PushDown ) return 0; while( iFirst<iEnd ){ - pItem = &pTabList->a[iFirst++]; Select *pS1; + pItem = &pTabList->a[iFirst++]; if( pItem->pSelect==0 ) continue; if( pItem->fg.viaCoroutine ) continue; if( pItem->zName==0 ) continue; @@ -6867,44 +6867,49 @@ static int sameSrcAlias(SrcItem *p0, SrcList *pSrc){ ** The subquery is implemented as a co-routine if all of the following are ** true: ** -** (1) Either of the following are true: -** (1a) The subquery must be the outer loop because it is either -** (i) the only term in the FROM clause, or because (ii) it -** is the left-most term and a CROSS JOIN or similar requires -** it to be the outer loop. subquery and there is nothing -** (1b) There is nothing that would prevent the subquery from -** being an outer loop and the SQLITE_PREPARE_SAFESQL flag -** is not set. -** (2) The subquery is not a CTE that should be materialized +** (1) The subquery will likely be implemented in the outer loop of +** the query. This will be the case if any one of the following +** conditions hold: +** (a) The subquery is the only term in the FROM clause +** (b) The subquery is the left-most term and a CROSS JOIN or similar +** requires it to be the outer loop +** (c) All of the following are true: +** (i) The subquery is the left-most subquery in the FROM clause +** (ii) There is nothing that would prevent the subquery from +** being used as the outer loop if the sqlite3WhereBegin() +** routine nominates it to that position. +** (iii) The SQLITE_PREPARE_SAFEOPT flag is not set +** (2) The subquery is not a CTE that should be materialized because of +** the AS MATERIALIZED keywords ** (3) The subquery is not part of a left operand for a RIGHT JOIN ** (4) The SQLITE_Coroutine optimization disable flag is not set ** (5) The subquery is not self-joined */ static int fromClauseTermCanBeCoroutine( - Parse *pParse, /* Parsing context */ - SrcList *pTabList, /* FROM clause */ - int i /* Which term of the FROM clause */ + Parse *pParse, /* Parsing context */ + SrcList *pTabList, /* FROM clause */ + int i /* Which term of the FROM clause holds the subquery */ ){ SrcItem *pItem = &pTabList->a[i]; if( pItem->fg.isCte && pItem->u2.pCteUse->eM10d==M10d_Yes ) return 0;/* (2) */ if( pTabList->a[0].fg.jointype & JT_LTORJ ) return 0; /* (3) */ if( OptimizationDisabled(pParse->db, SQLITE_Coroutines) ) return 0; /* (4) */ if( isSelfJoinView(pTabList, pItem, i+1, pTabList->nSrc)!=0 ){ - return 0; /* (5) */ + return 0; /* (5) */ } if( i==0 ){ - if( pTabList->nSrc==1 ) return 1; /* (1a-i) */ - if( pTabList->a[1].fg.jointype & JT_CROSS ) return 1; /* (1a-ii) */ - if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0; + if( pTabList->nSrc==1 ) return 1; /* (1a) */ + if( pTabList->a[1].fg.jointype & JT_CROSS ) return 1; /* (1b) */ + if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0; /* (1c-iii) */ return 1; } - if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0; + if( pParse->prepFlags & SQLITE_PREPARE_SAFEOPT ) return 0; /* (1c-iii) */ while( 1 /*exit-by-break*/ ){ - if( pItem->fg.jointype & (JT_OUTER|JT_CROSS) ) return 0; + if( pItem->fg.jointype & (JT_OUTER|JT_CROSS) ) return 0; /* (1c-ii) */ if( i==0 ) break; i--; pItem--; - if( pItem->pSelect!=0 ) return 0; + if( pItem->pSelect!=0 ) return 0; /* (1c-i) */ } return 1; } |