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There was no code to handle foreign key constraints on partitioned tables in the case of ALTER TABLE DETACH; and if you happened to ATTACH a partition that already had an equivalent constraint, that one was ignored and a new constraint was created. Adding this to the fact that foreign key cloning reuses the constraint name on the partition instead of generating a new name (as it probably should, to cater to SQL standard rules about constraint naming within schemas), the result was a pretty poor user experience -- the most visible failure was that just detaching a partition and re-attaching it failed with an error such as ERROR: duplicate key value violates unique constraint "pg_constraint_conrelid_contypid_conname_index" DETAIL: Key (conrelid, contypid, conname)=(26702, 0, test_result_asset_id_fkey) already exists. because it would try to create an identically-named constraint in the partition. To make matters worse, if you tried to drop the constraint in the now-independent partition, that would fail because the constraint was still seen as dependent on the constraint in its former parent partitioned table: ERROR: cannot drop inherited constraint "test_result_asset_id_fkey" of relation "test_result_cbsystem_0001_0050_monthly_2018_09" This fix attacks the problem from two angles: first, when the partition is detached, the constraint is also marked as independent, so the drop now works. Second, when the partition is re-attached, we scan existing constraints searching for one matching the FK in the parent, and if one exists, we link that one to the parent constraint. So we don't end up with a duplicate -- and better yet, we don't need to scan the referenced table to verify that the constraint holds. To implement this I made a small change to previously planner-only struct ForeignKeyCacheInfo to contain the constraint OID; also relcache now maintains the list of FKs for partitioned tables too. Backpatch to 11. Reported-by: Michael Vitale (bug #15425) Discussion: https://postgr.es/m/15425-2dbc9d2aa999f816@postgresql.org |
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| .. | ||
| .gitignore | ||
| aclchk.c | ||
| catalog.c | ||
| Catalog.pm | ||
| dependency.c | ||
| genbki.pl | ||
| heap.c | ||
| index.c | ||
| indexing.c | ||
| information_schema.sql | ||
| Makefile | ||
| namespace.c | ||
| objectaccess.c | ||
| objectaddress.c | ||
| partition.c | ||
| pg_aggregate.c | ||
| pg_collation.c | ||
| pg_constraint.c | ||
| pg_conversion.c | ||
| pg_db_role_setting.c | ||
| pg_depend.c | ||
| pg_enum.c | ||
| pg_inherits.c | ||
| pg_largeobject.c | ||
| pg_namespace.c | ||
| pg_operator.c | ||
| pg_proc.c | ||
| pg_publication.c | ||
| pg_range.c | ||
| pg_shdepend.c | ||
| pg_subscription.c | ||
| pg_type.c | ||
| sql_feature_packages.txt | ||
| sql_features.txt | ||
| storage.c | ||
| system_views.sql | ||
| toasting.c | ||