database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-09 06:21:09 +03:00
Code Activity

Consider cheap startup paths in add_paths_to_append_rel

Browse Source 
6b94e7a6d did this for ordered append paths to allow fast startup
MergeAppends, however, nothing was done for the Append case.

Here we adjust add_paths_to_append_rel() to have it build an AppendPath
containing the cheapest startup paths from each of the child relations
when the append rel has "consider_startup" set.

Author: Andy Fan, David Rowley
Discussion: https://www.postgresql.org/message-id/CAKU4AWrXSkUV=Pt-gRxQT7EbfUeNssprGyNsB=5mJibFZ6S3ww@mail.gmail.com
This commit is contained in:
David Rowley
2023-10-05 21:03:10 +13:00
parent 0b053e78b5
commit a8a968a821
3 changed files with 53 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
src/backend/optimizer/path/allpaths.c
View File

@@ -1307,6 +1307,8 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
{
List *subpaths = NIL;
bool subpaths_valid = true;
List *startup_subpaths = NIL;
bool startup_subpaths_valid = true;
List *partial_subpaths = NIL;
List *pa_partial_subpaths = NIL;
List *pa_nonpartial_subpaths = NIL;
@@ -1346,6 +1348,20 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
else
subpaths_valid = false;
/*
* When the planner is considering cheap startup plans, we'll also
* collect all the cheapest_startup_paths and build an AppendPath
* containing those as subpaths.
*/
if (rel->consider_startup && childrel->pathlist != NIL &&
childrel->cheapest_startup_path->param_info == NULL)
accumulate_append_subpath(childrel->cheapest_startup_path,
&startup_subpaths,
NULL);
else
startup_subpaths_valid = false;
/* Same idea, but for a partial plan. */
if (childrel->partial_pathlist != NIL)
{
@@ -1478,6 +1494,11 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel,
NIL, NULL, 0, false,
-1));
/* build an AppendPath for the cheap startup paths, if valid */
if (startup_subpaths_valid)
add_path(rel, (Path *) create_append_path(root, rel, startup_subpaths,
NIL, NIL, NULL, 0, false, -1));
/*
* Consider an append of unordered, unparameterized partial paths. Make
* it parallel-aware if possible.