diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/select.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/src/select.c b/src/select.c index 3672a7c0f..80b488777 100644 --- a/src/select.c +++ b/src/select.c @@ -6727,18 +6727,19 @@ int sqlite3Select( /* Generate code to implement the subquery ** - ** The subquery is implemented as a co-routine if: + ** The subquery is implemented as a co-routine all of the following are + ** true: + ** ** (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 should be materialized - ** - ** TODO: Are there other reasons beside (1) and (2) to use a co-routine - ** implementation? + ** (3) the subquery is not part of a left operand for a RIGHT JOIN */ if( i==0 && (pTabList->nSrc==1 || (pTabList->a[1].fg.jointype&(JT_OUTER|JT_CROSS))!=0) /* (1) */ && (pItem->fg.isCte==0 || pItem->u2.pCteUse->eM10d!=M10d_Yes) /* (2) */ + && (pTabList->a[0].fg.jointype & JT_LTORJ)==0 /* (3) */ ){ /* Implement a co-routine that will return a single row of the result ** set on each invocation. @@ -6755,9 +6756,6 @@ int sqlite3Select( pItem->pTab->nRowLogEst = pSub->nSelectRow; pItem->fg.viaCoroutine = 1; pItem->regResult = dest.iSdst; - if( pItem->fg.jointype & JT_LTORJ ){ - sqlite3VdbeAddOp3(v, OP_Null, 0, dest.iSdst, dest.iSdst+dest.nSdst-1); - } sqlite3VdbeEndCoroutine(v, pItem->regReturn); sqlite3VdbeJumpHere(v, addrTop-1); sqlite3ClearTempRegCache(pParse); |