diff options
Diffstat (limited to 'src/backend/executor')
| -rw-r--r-- | src/backend/executor/nodeLimit.c | 33 | ||||
| -rw-r--r-- | src/backend/executor/nodeSort.c | 12 |
2 files changed, 42 insertions, 3 deletions
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c index d2ecb3722f7..9d40952647d 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 1.29 2007/01/05 22:19:28 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeLimit.c,v 1.30 2007/05/04 01:13:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -280,6 +280,37 @@ recompute_limits(LimitState *node) /* Reset position to start-of-scan */ node->position = 0; node->subSlot = NULL; + + /* + * If we have a COUNT, and our input is a Sort node, notify it that it can + * use bounded sort. + * + * This is a bit of a kluge, but we don't have any more-abstract way of + * communicating between the two nodes; and it doesn't seem worth trying + * to invent one without some more examples of special communication needs. + * + * Note: it is the responsibility of nodeSort.c to react properly to + * changes of these parameters. If we ever do redesign this, it'd be + * a good idea to integrate this signaling with the parameter-change + * mechanism. + */ + if (IsA(outerPlanState(node), SortState)) + { + SortState *sortState = (SortState *) outerPlanState(node); + int64 tuples_needed = node->count + node->offset; + + /* negative test checks for overflow */ + if (node->noCount || tuples_needed < 0) + { + /* make sure flag gets reset if needed upon rescan */ + sortState->bounded = false; + } + else + { + sortState->bounded = true; + sortState->bound = tuples_needed; + } + } } /* ---------------------------------------------------------------- diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c index 97b5c4ff150..5b18235258f 100644 --- a/src/backend/executor/nodeSort.c +++ b/src/backend/executor/nodeSort.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/nodeSort.c,v 1.60 2007/01/09 02:14:11 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/nodeSort.c,v 1.61 2007/05/04 01:13:44 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -89,6 +89,8 @@ ExecSort(SortState *node) plannode->nullsFirst, work_mem, node->randomAccess); + if (node->bounded) + tuplesort_set_bound(tuplesortstate, node->bound); node->tuplesortstate = (void *) tuplesortstate; /* @@ -119,6 +121,8 @@ ExecSort(SortState *node) * finally set the sorted flag to true */ node->sort_Done = true; + node->bounded_Done = node->bounded; + node->bound_Done = node->bound; SO1_printf("ExecSort: %s\n", "sorting done"); } @@ -167,6 +171,7 @@ ExecInitSort(Sort *node, EState *estate, int eflags) EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)) != 0; + sortstate->bounded = false; sortstate->sort_Done = false; sortstate->tuplesortstate = NULL; @@ -307,11 +312,14 @@ ExecReScanSort(SortState *node, ExprContext *exprCtxt) /* * If subnode is to be rescanned then we forget previous sort results; we - * have to re-read the subplan and re-sort. + * have to re-read the subplan and re-sort. Also must re-sort if the + * bounded-sort parameters changed or we didn't select randomAccess. * * Otherwise we can just rewind and rescan the sorted output. */ if (((PlanState *) node)->lefttree->chgParam != NULL || + node->bounded != node->bounded_Done || + node->bound != node->bound_Done || !node->randomAccess) { node->sort_Done = false; |