diff options
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 20 | ||||
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 12 | ||||
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 2 | ||||
| -rw-r--r-- | src/test/regress/expected/union.out | 28 | ||||
| -rw-r--r-- | src/test/regress/sql/union.sql | 18 |
5 files changed, 71 insertions, 9 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 715f44675f8..59b72339163 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -635,10 +635,15 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, * accumulate_append_subpath * Add a subpath to the list being built for an Append or MergeAppend * - * It's possible that the child is itself an Append path, in which case - * we can "cut out the middleman" and just add its child paths to our - * own list. (We don't try to do this earlier because we need to - * apply both levels of transformation to the quals.) + * It's possible that the child is itself an Append or MergeAppend path, in + * which case we can "cut out the middleman" and just add its child paths to + * our own list. (We don't try to do this earlier because we need to apply + * both levels of transformation to the quals.) + * + * Note that if we omit a child MergeAppend in this way, we are effectively + * omitting a sort step, which seems fine: if the parent is to be an Append, + * its result would be unsorted anyway, while if the parent is to be a + * MergeAppend, there's no point in a separate sort on a child. */ static List * accumulate_append_subpath(List *subpaths, Path *path) @@ -650,6 +655,13 @@ accumulate_append_subpath(List *subpaths, Path *path) /* list_copy is important here to avoid sharing list substructure */ return list_concat(subpaths, list_copy(apath->subpaths)); } + else if (IsA(path, MergeAppendPath)) + { + MergeAppendPath *mpath = (MergeAppendPath *) path; + + /* list_copy is important here to avoid sharing list substructure */ + return list_concat(subpaths, list_copy(mpath->subpaths)); + } else return lappend(subpaths, path); } diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 2a3826cfa5e..d89feb34b32 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -1850,16 +1850,20 @@ add_child_rel_equivalences(PlannerInfo *root, if (cur_ec->ec_has_volatile) continue; - /* No point in searching if parent rel not mentioned in eclass */ - if (!bms_is_subset(parent_rel->relids, cur_ec->ec_relids)) + /* + * No point in searching if parent rel not mentioned in eclass; but + * we can't tell that for sure if parent rel is itself a child. + */ + if (parent_rel->reloptkind == RELOPT_BASEREL && + !bms_is_subset(parent_rel->relids, cur_ec->ec_relids)) continue; foreach(lc2, cur_ec->ec_members) { EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2); - if (cur_em->em_is_child) - continue; /* ignore children here */ + if (cur_em->em_is_const) + continue; /* ignore consts here */ /* Does it reference (only) parent_rel? */ if (bms_equal(cur_em->em_relids, parent_rel->relids)) diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index c246468c929..682217d1503 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -700,7 +700,7 @@ create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path) /* Compute sort column info, and adjust MergeAppend's tlist as needed */ (void) prepare_sort_from_pathkeys(root, plan, pathkeys, - NULL, + best_path->path.parent->relids, NULL, true, &node->numCols, diff --git a/src/test/regress/expected/union.out b/src/test/regress/expected/union.out index 2c30e485c82..9b6eb8a26ab 100644 --- a/src/test/regress/expected/union.out +++ b/src/test/regress/expected/union.out @@ -500,9 +500,37 @@ explain (costs off) Index Cond: (ab = 'ab'::text) (6 rows) +-- +-- Test that ORDER BY for UNION ALL can be pushed down to inheritance +-- children. +-- reset enable_seqscan; reset enable_indexscan; reset enable_bitmapscan; +create table events (event_id int primary key); +NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "events_pkey" for table "events" +create table other_events (event_id int primary key); +NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "other_events_pkey" for table "other_events" +create table events_child () inherits (events); +explain (costs off) +select event_id + from (select event_id from events + union all + select event_id from other_events) ss + order by event_id; + QUERY PLAN +---------------------------------------------------------------- + Result + -> Merge Append + Sort Key: public.events.event_id + -> Index Scan using events_pkey on events + -> Sort + Sort Key: public.events.event_id + -> Seq Scan on events_child events + -> Index Scan using other_events_pkey on other_events +(8 rows) + +drop table events_child, events, other_events; -- Test constraint exclusion of UNION ALL subqueries explain (costs off) SELECT * FROM diff --git a/src/test/regress/sql/union.sql b/src/test/regress/sql/union.sql index f3c9d113827..86207d25b09 100644 --- a/src/test/regress/sql/union.sql +++ b/src/test/regress/sql/union.sql @@ -196,10 +196,28 @@ explain (costs off) SELECT * FROM t2) t WHERE ab = 'ab'; +-- +-- Test that ORDER BY for UNION ALL can be pushed down to inheritance +-- children. +-- + reset enable_seqscan; reset enable_indexscan; reset enable_bitmapscan; +create table events (event_id int primary key); +create table other_events (event_id int primary key); +create table events_child () inherits (events); + +explain (costs off) +select event_id + from (select event_id from events + union all + select event_id from other_events) ss + order by event_id; + +drop table events_child, events, other_events; + -- Test constraint exclusion of UNION ALL subqueries explain (costs off) SELECT * FROM |