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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 |