git.postgresql.org Git - postgresql.git/commitdiff

git projects / postgresql.git / commitdiff

Simplify create_merge_append_path for clarity

author Richard Guo <rguo@postgresql.org>

2024年7月29日 02:33:18 +0000 (11:33 +0900)

committer Richard Guo <rguo@postgresql.org>

2024年7月29日 02:33:18 +0000 (11:33 +0900)

We don't currently support parameterized MergeAppend paths: there's
little use for an ordered path on the inside of a nestloop. Given
this, we can simplify create_merge_append_path by directly setting
param_info to NULL instead of calling get_appendrel_parampathinfo. We
can also simplify the Assert for child paths a little bit.

This change won't make any measurable difference in performance; it's
just for clarity's sake.

Author: Richard Guo
Reviewed-by: Alena Rybakina, Paul A Jungwirth
Discussion: https://postgr.es/m/CAMbWs4_n1bgH2nACMuGsXZct3KH6PBFS0tPdQsXdstRfyxTunQ@mail.gmail.com

src/backend/optimizer/util/pathnode.c patch | blob | blame | history

diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c

index b8b1eae295ec843a3bfaf56c8d5cf804f9635b4f..54e042a8a59c99c4f36d24cc772a9ddc4afa0d6f 100644 (file)

--- a/src/backend/optimizer/util/pathnode.c

+++ b/src/backend/optimizer/util/pathnode.c

@@ -1423,11 +1423,16 @@ create_merge_append_path(PlannerInfo *root,

Cost input_total_cost;

ListCell *l;

+ /*

+ * We don't currently support parameterized MergeAppend paths, as

+ * explained in the comments for generate_orderedappend_paths.

+ */

+ Assert(bms_is_empty(rel->lateral_relids) && bms_is_empty(required_outer));

pathnode->path.pathtype = T_MergeAppend;

pathnode->path.parent = rel;

pathnode->path.pathtarget = rel->reltarget;

- pathnode->path.param_info = get_appendrel_parampathinfo(rel,

- required_outer);

+ pathnode->path.param_info = NULL;

pathnode->path.parallel_aware = false;

pathnode->path.parallel_safe = rel->consider_parallel;

pathnode->path.parallel_workers = 0;

@@ -1453,6 +1458,9 @@ create_merge_append_path(PlannerInfo *root,

{

Path *subpath = (Path *) lfirst(l);

+ /* All child paths should be unparameterized */

+ Assert(bms_is_empty(PATH_REQ_OUTER(subpath)));

pathnode->path.rows += subpath->rows;

pathnode->path.parallel_safe = pathnode->path.parallel_safe &&

subpath->parallel_safe;

@@ -1480,9 +1488,6 @@ create_merge_append_path(PlannerInfo *root,

input_startup_cost += sort_path.startup_cost;

input_total_cost += sort_path.total_cost;

}

- /* All child paths must have same parameterization */

- Assert(bms_equal(PATH_REQ_OUTER(subpath), required_outer));

}

This is the main PostgreSQL git repository.

RSS Atom