diff options
Diffstat (limited to 'src/backend/executor/nodeLimit.c')
| -rw-r--r-- | src/backend/executor/nodeLimit.c | 34 |
1 files changed, 23 insertions, 11 deletions
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c index 9d40952647d..76296cfd877 100644 --- a/src/backend/executor/nodeLimit.c +++ b/src/backend/executor/nodeLimit.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/nodeLimit.c,v 1.30 2007/05/04 01:13:43 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeLimit.c,v 1.31 2007/05/17 19:35:08 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -55,17 +55,22 @@ ExecLimit(LimitState *node) case LIMIT_INITIAL: /* - * If backwards scan, just return NULL without changing state. + * First call for this node, so compute limit/offset. (We can't do + * this any earlier, because parameters from upper nodes will not + * be set during ExecInitLimit.) This also sets position = 0 + * and changes the state to LIMIT_RESCAN. */ - if (!ScanDirectionIsForward(direction)) - return NULL; + recompute_limits(node); + + /* FALL THRU */ + + case LIMIT_RESCAN: /* - * First call for this scan, so compute limit/offset. (We can't do - * this any earlier, because parameters from upper nodes may not - * be set until now.) This also sets position = 0. + * If backwards scan, just return NULL without changing state. */ - recompute_limits(node); + if (!ScanDirectionIsForward(direction)) + return NULL; /* * Check for empty window; if so, treat like empty subplan. @@ -217,7 +222,7 @@ ExecLimit(LimitState *node) } /* - * Evaluate the limit/offset expressions --- done at start of each scan. + * Evaluate the limit/offset expressions --- done at startup or rescan. * * This is also a handy place to reset the current-position state info. */ @@ -281,6 +286,9 @@ recompute_limits(LimitState *node) node->position = 0; node->subSlot = NULL; + /* Set state-machine state */ + node->lstate = LIMIT_RESCAN; + /* * If we have a COUNT, and our input is a Sort node, notify it that it can * use bounded sort. @@ -403,8 +411,12 @@ ExecEndLimit(LimitState *node) void ExecReScanLimit(LimitState *node, ExprContext *exprCtxt) { - /* resetting lstate will force offset/limit recalculation */ - node->lstate = LIMIT_INITIAL; + /* + * Recompute limit/offset in case parameters changed, and reset the + * state machine. We must do this before rescanning our child node, + * in case it's a Sort that we are passing the parameters down to. + */ + recompute_limits(node); /* * if chgParam of subnode is not null then plan will be re-scanned by |