diff options
| -rw-r--r-- | src/backend/executor/nodeIncrementalSort.c | 45 | ||||
| -rw-r--r-- | src/test/regress/expected/incremental_sort.out | 15 | ||||
| -rw-r--r-- | src/test/regress/sql/incremental_sort.sql | 4 |
3 files changed, 30 insertions, 34 deletions
diff --git a/src/backend/executor/nodeIncrementalSort.c b/src/backend/executor/nodeIncrementalSort.c index 82fa800cb17..459c879f0bb 100644 --- a/src/backend/executor/nodeIncrementalSort.c +++ b/src/backend/executor/nodeIncrementalSort.c @@ -288,9 +288,7 @@ switchToPresortedPrefixMode(PlanState *pstate) { IncrementalSortState *node = castNode(IncrementalSortState, pstate); ScanDirection dir; - int64 nTuples = 0; - bool lastTuple = false; - bool firstTuple = true; + int64 nTuples; TupleDesc tupDesc; PlanState *outerNode; IncrementalSort *plannode = castNode(IncrementalSort, node->ss.ps.plan); @@ -343,20 +341,16 @@ switchToPresortedPrefixMode(PlanState *pstate) * Copy as many tuples as we can (i.e., in the same prefix key group) from * the full sort state to the prefix sort state. */ - for (;;) + for (nTuples = 0; nTuples < node->n_fullsort_remaining; nTuples++) { - lastTuple = node->n_fullsort_remaining - nTuples == 1; - /* * When we encounter multiple prefix key groups inside the full sort * tuplesort we have to carry over the last read tuple into the next * batch. */ - if (firstTuple && !TupIsNull(node->transfer_tuple)) + if (nTuples == 0 && !TupIsNull(node->transfer_tuple)) { tuplesort_puttupleslot(node->prefixsort_state, node->transfer_tuple); - nTuples++; - /* The carried over tuple is our new group pivot tuple. */ ExecCopySlot(node->group_pivot, node->transfer_tuple); } @@ -376,7 +370,6 @@ switchToPresortedPrefixMode(PlanState *pstate) if (isCurrentGroup(node, node->group_pivot, node->transfer_tuple)) { tuplesort_puttupleslot(node->prefixsort_state, node->transfer_tuple); - nTuples++; } else { @@ -395,27 +388,10 @@ switchToPresortedPrefixMode(PlanState *pstate) */ ExecClearTuple(node->group_pivot); - /* - * Also make sure we take the didn't-consume-all-the-tuples - * path below, even if this happened to be the last tuple of - * the batch. - */ - lastTuple = false; + /* Break out of for-loop early */ break; } } - - firstTuple = false; - - /* - * If we've copied all of the tuples from the full sort state into the - * prefix sort state, then we don't actually know that we've yet found - * the last tuple in that prefix key group until we check the next - * tuple from the outer plan node, so we retain the current group - * pivot tuple prefix key group comparison. - */ - if (lastTuple) - break; } /* @@ -428,14 +404,15 @@ switchToPresortedPrefixMode(PlanState *pstate) node->n_fullsort_remaining -= nTuples; SO1_printf("Setting n_fullsort_remaining to " INT64_FORMAT "\n", node->n_fullsort_remaining); - if (lastTuple) + if (node->n_fullsort_remaining == 0) { /* - * We've confirmed that all tuples remaining in the full sort batch is - * in the same prefix key group and moved all of those tuples into the - * presorted prefix tuplesort. Now we can save our pivot comparison - * tuple and continue fetching tuples from the outer execution node to - * load into the presorted prefix tuplesort. + * We've found that all tuples remaining in the full sort batch are in + * the same prefix key group and moved all of those tuples into the + * presorted prefix tuplesort. We don't know that we've yet found the + * last tuple in the current prefix key group, so save our pivot + * comparison tuple and continue fetching tuples from the outer + * execution node to load into the presorted prefix tuplesort. */ ExecCopySlot(node->group_pivot, node->transfer_tuple); SO_printf("Setting execution_status to INCSORT_LOADPREFIXSORT (switchToPresortedPrefixMode)\n"); diff --git a/src/test/regress/expected/incremental_sort.out b/src/test/regress/expected/incremental_sort.out index d5745838440..68ca321163b 100644 --- a/src/test/regress/expected/incremental_sort.out +++ b/src/test/regress/expected/incremental_sort.out @@ -676,6 +676,21 @@ select * from (select * from t order by a) s order by a, b limit 70; (70 rows) -- Checks case where we hit a group boundary at the last tuple of a batch. +-- Because the full sort state is bounded, we scan 64 tuples (the mode +-- transition point) but only retain 5. Thus when we transition modes, all +-- tuples in the full sort state have different prefix keys. +explain (costs off) select * from (select * from t order by a) s order by a, b limit 5; + QUERY PLAN +--------------------------------- + Limit + -> Incremental Sort + Sort Key: t.a, t.b + Presorted Key: t.a + -> Sort + Sort Key: t.a + -> Seq Scan on t +(7 rows) + select * from (select * from t order by a) s order by a, b limit 5; a | b ---+--- diff --git a/src/test/regress/sql/incremental_sort.sql b/src/test/regress/sql/incremental_sort.sql index 9965fcd7776..81429164d45 100644 --- a/src/test/regress/sql/incremental_sort.sql +++ b/src/test/regress/sql/incremental_sort.sql @@ -150,6 +150,10 @@ analyze t; explain (costs off) select * from (select * from t order by a) s order by a, b limit 70; select * from (select * from t order by a) s order by a, b limit 70; -- Checks case where we hit a group boundary at the last tuple of a batch. +-- Because the full sort state is bounded, we scan 64 tuples (the mode +-- transition point) but only retain 5. Thus when we transition modes, all +-- tuples in the full sort state have different prefix keys. +explain (costs off) select * from (select * from t order by a) s order by a, b limit 5; select * from (select * from t order by a) s order by a, b limit 5; -- Test rescan. |