diff options
Diffstat (limited to 'src/backend/executor/nodeIncrementalSort.c')
| -rw-r--r-- | src/backend/executor/nodeIncrementalSort.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c index 39ba11cdf76..ae7ad5d7bde 100644 --- a/src/backend/executor/nodeIncrementalSort.c +++ b/src/backend/executor/nodeIncrementalSort.c @@ -986,12 +986,11 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags) SO_printf("ExecInitIncrementalSort: initializing sort node\n"); /* - * Incremental sort can't be used with either EXEC_FLAG_REWIND, - * EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK, because we only one of many sort - * batches in the current sort state. + * Incremental sort can't be used with EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK, + * because the current sort state contains only one sort batch rather than + * the full result set. */ - Assert((eflags & (EXEC_FLAG_BACKWARD | - EXEC_FLAG_MARK)) == 0); + Assert((eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)) == 0); /* Initialize state structure. */ incrsortstate = makeNode(IncrementalSortState); @@ -1041,11 +1040,11 @@ ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags) /* * Initialize child nodes. * - * We shield the child node from the need to support REWIND, BACKWARD, or - * MARK/RESTORE. + * Incremental sort does not support backwards scans and mark/restore, so + * we don't bother removing the flags from eflags here. We allow passing + * a REWIND flag, because although incremental sort can't use it, the child + * nodes may be able to do something more useful. */ - eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK); - outerPlanState(incrsortstate) = ExecInitNode(outerPlan(node), estate, eflags); /* @@ -1126,7 +1125,8 @@ ExecReScanIncrementalSort(IncrementalSortState *node) * store all tuples at once for the full sort. * * So even if EXEC_FLAG_REWIND is set we just reset all of our state and - * reexecute the sort along with the child node below us. + * re-execute the sort along with the child node. Incremental sort itself + * can't do anything smarter, but maybe the child nodes can. * * In theory if we've only filled the full sort with one batch (and haven't * reset it for a new batch yet) then we could efficiently rewind, but |