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Make it cheap to check if a relation is modified by a query

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Save the range table indexes of result relations and row mark relations
in separate bitmapsets in the PlannedStmt. Precomputing them allows
cheap membership checks during execution. Together, these two groups
approximate all relations that will be modified by a query. This
includes relations targeted by INSERT, UPDATE, DELETE, and MERGE as well
as relations with any row mark (like SELECT FOR UPDATE).

Future work will use information on whether or not a relation is
modified by a query in a heuristic.

PlannedStmt->resultRelations is only used in a membership check, so it
will be removed in a separate commit.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/F5CDD1B5-628C-44A1-9F85-3958C626F6A9%40gmail.com
This commit is contained in:
Melanie Plageman 2026-03-30 09:38:03 -04:00
parent 1bd6f22f43
commit 0f4c170cf3
3 changed files with 27 additions and 1 deletions
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7
src/backend/executor/execParallel.c
View file

@ -212,6 +212,13 @@ ExecSerializePlan(Plan *plan, EState *estate)
pstmt->rewindPlanIDs = NULL;
pstmt->rowMarks = NIL;
/*
* Pass the row mark and result relation relids to parallel workers. They
* may need to check them to inform heuristics.
*/
pstmt->rowMarkRelids = estate->es_plannedstmt->rowMarkRelids;
pstmt->resultRelationRelids = estate->es_plannedstmt->resultRelationRelids;
pstmt->relationOids = NIL;
pstmt->invalItems = NIL; /* workers can't replan anyway... */
pstmt->paramExecTypes = estate->es_plannedstmt->paramExecTypes;

15
src/backend/optimizer/plan/planner.c
View file

@ -341,7 +341,8 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
Path *best_path;
Plan *top_plan;
ListCell *lp,
*lr;
*lr,
*lc;
/*
* Set up global state for this planner invocation. This data is needed
@ -661,6 +662,18 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
result->subplans = glob->subplans;
result->rewindPlanIDs = glob->rewindPlanIDs;
result->rowMarks = glob->finalrowmarks;
/*
* Compute resultRelationRelids and rowMarkRelids from resultRelations and
* rowMarks. These can be used for cheap membership checks.
*/
foreach(lc, glob->resultRelations)
result->resultRelationRelids = bms_add_member(result->resultRelationRelids,
lfirst_int(lc));
foreach(lc, glob->finalrowmarks)
result->rowMarkRelids = bms_add_member(result->rowMarkRelids,
((PlanRowMark *) lfirst(lc))->rti);
result->relationOids = glob->relationOids;
result->invalItems = glob->invalItems;
result->paramExecTypes = glob->paramExecTypes;

6
src/include/nodes/plannodes.h
View file

@ -121,6 +121,9 @@ typedef struct PlannedStmt
/* integer list of RT indexes, or NIL */
List *resultRelations;
/* RT indexes of relations targeted by INSERT/UPDATE/DELETE/MERGE */
Bitmapset *resultRelationRelids;
/* list of AppendRelInfo nodes */
List *appendRelations;
@ -138,6 +141,9 @@ typedef struct PlannedStmt
/* a list of PlanRowMark's */
List *rowMarks;
/* RT indexes of relations with row marks */
Bitmapset *rowMarkRelids;
/* OIDs of relations the plan depends on */
List *relationOids;