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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2022-07-30 13:05:15 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2022-07-30 13:05:15 -0400 |
| commit | a3699c599ced03ace09646b74b8299d8f570ca76 (patch) | |
| tree | 0215a2d31a3c430d51fb6e086f5999092bbcd601 | |
| parent | d92f2bc0dae35747387f006519a74d3058a6bcb8 (diff) | |
| download | postgresql-a3699c599ced03ace09646b74b8299d8f570ca76.tar.gz postgresql-a3699c599ced03ace09646b74b8299d8f570ca76.zip | |
Fix incorrect is-this-the-topmost-join tests in parallel planning.
Two callers of generate_useful_gather_paths were testing the wrong
thing when deciding whether to call that function: they checked for
being at the top of the current join subproblem, rather than being at
the actual top join. This'd result in failing to construct parallel
paths for a sub-join for which they might be useful.
While set_rel_pathlist() isn't actively broken, it seems best to
make its identical-in-intention test for this be like the other two.
This has been wrong all along, but given the lack of field complaints
I'm hesitant to back-patch into stable branches; we usually prefer
to avoid non-bug-fix changes in plan choices in minor releases.
It seems not too late for v15 though.
Richard Guo, reviewed by Antonin Houska and Tom Lane
Discussion: https://postgr.es/m/CAMbWs4-mH8Zf87-w+3P2J=nJB+5OyicO28ia9q_9o=Lamf_VHg@mail.gmail.com
| -rw-r--r-- | src/backend/optimizer/geqo/geqo_eval.c | 2 | ||||
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 9 |
2 files changed, 5 insertions, 6 deletions
diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c index de695c0a789..004481d6082 100644 --- a/src/backend/optimizer/geqo/geqo_eval.c +++ b/src/backend/optimizer/geqo/geqo_eval.c @@ -273,7 +273,7 @@ merge_clump(PlannerInfo *root, List *clumps, Clump *new_clump, int num_gene, * rel once we know the final targetlist (see * grouping_planner). */ - if (old_clump->size + new_clump->size < num_gene) + if (!bms_equal(joinrel->relids, root->all_baserels)) generate_useful_gather_paths(root, joinrel, false); /* Find and save the cheapest paths for this joinrel */ diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index e9342097e52..4cf0cdc4beb 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -553,12 +553,11 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, * its own pool of workers. Instead, we'll consider gathering partial * paths for the parent appendrel. * - * Also, if this is the topmost scan/join rel (that is, the only baserel), - * we postpone gathering until the final scan/join targetlist is available - * (see grouping_planner). + * Also, if this is the topmost scan/join rel, we postpone gathering until + * the final scan/join targetlist is available (see grouping_planner). */ if (rel->reloptkind == RELOPT_BASEREL && - bms_membership(root->all_baserels) != BMS_SINGLETON) + !bms_equal(rel->relids, root->all_baserels)) generate_useful_gather_paths(root, rel, false); /* Now find the cheapest of the paths for this rel */ @@ -3402,7 +3401,7 @@ standard_join_search(PlannerInfo *root, int levels_needed, List *initial_rels) * partial paths. We'll do the same for the topmost scan/join rel * once we know the final targetlist (see grouping_planner). */ - if (lev < levels_needed) + if (!bms_equal(rel->relids, root->all_baserels)) generate_useful_gather_paths(root, rel, false); /* Find and save the cheapest paths for this rel */ |