作者
digoal
日期
2021-03-11
标签
PostgreSQL , 分区表 , cache
背景
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=c3ffe34863688115dd7878f118f2a123bafd8a26
```
Avoid creating duplicate cached plans for inherited FK constraints.
author Tom Lane tgl@sss.pgh.pa.us
Wed, 10 Mar 2021 19:22:31 +0000 (14:22 -0500)
committer Tom Lane tgl@sss.pgh.pa.us
Wed, 10 Mar 2021 19:22:31 +0000 (14:22 -0500)
commit c3ffe34863688115dd7878f118f2a123bafd8a26
tree 7cf4577a73c9ae4c4e47f9bbeef25f4c188bb59c tree | snapshot
parent b12436340adf27aa3d334c92579e6662dd3090ce commit | diff
Avoid creating duplicate cached plans for inherited FK constraints.
When a foreign key constraint is applied to a partitioned table, each
leaf partition inherits a similar FK constraint. We were processing all
of those constraints independently, meaning that in large partitioning
trees we'd build up large collections of cached FK-checking query plans.
However, in all cases but one, the generated queries are actually
identical for all members of the inheritance tree (because, in most
cases, the query only mentions the topmost table of the other side of
the FK relationship). So we can share a single cached plan among all
the partitions, saving memory, not to mention time to build and maintain
the cached plans.
Keisuke Kuroda and Amit Langote
Discussion: https://postgr.es/m/cab4b85d-9292-967d-adf2-be0d803c3e23@nttcom.co.jp_1
```
+-- test that ri_Check_Pk_Match() scans the correct partition for a deferred
+-- ON DELETE/UPDATE NO ACTION constraint
+CREATE SCHEMA fkpart10
+ CREATE TABLE tbl1(f1 int PRIMARY KEY) PARTITION BY RANGE(f1)
+ CREATE TABLE tbl1_p1 PARTITION OF tbl1 FOR VALUES FROM (minvalue) TO (1)
+ CREATE TABLE tbl1_p2 PARTITION OF tbl1 FOR VALUES FROM (1) TO (maxvalue)
+ CREATE TABLE tbl2(f1 int REFERENCES tbl1 DEFERRABLE INITIALLY DEFERRED);
+INSERT INTO fkpart10.tbl1 VALUES (0), (1);
+INSERT INTO fkpart10.tbl2 VALUES (0), (1);
+BEGIN;
+DELETE FROM fkpart10.tbl1 WHERE f1 = 0;
+UPDATE fkpart10.tbl1 SET f1 = 2 WHERE f1 = 1;
+INSERT INTO fkpart10.tbl1 VALUES (0), (1);
+COMMIT;
+DROP SCHEMA fkpart10 CASCADE;
+NOTICE: drop cascades to 2 other objects
+DETAIL: drop cascades to table fkpart10.tbl1
+drop cascades to table fkpart10.tbl2
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