When creating a foreign key in a partitioned table, if some partitions
already have equivalent constraints, we wastefully create duplicates of
the constraints instead of attaching to the existing ones. That's
inconsistent with the de-duplication that is applied when a table is
attached as a partition. To fix, reuse the FK-cloning code instead of
having a separate code path.
Backpatch to Postgres 11. This is a subtle behavior change, but surely
a welcome one since there's no use in having duplicate foreign keys.
Discovered by Álvaro Herrera while thinking about a different problem
reported by Jesper Pedersen (bug #15587).
Author: Álvaro Herrera
Discussion: https://postgr.es/m/
201901151935.zfadrzvyof4k@alvherre.pgsql
if (recurse && rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
{
PartitionDesc partdesc;
+ Relation pg_constraint;
+ List *cloned = NIL;
+ ListCell *cell;
+ pg_constraint = heap_open(ConstraintRelationId, RowExclusiveLock);
partdesc = RelationGetPartitionDesc(rel);
for (i = 0; i < partdesc->nparts; i++)
{
Oid partitionId = partdesc->oids[i];
Relation partition = heap_open(partitionId, lockmode);
- AlteredTableInfo *childtab;
- ObjectAddress childAddr;
CheckTableNotInUse(partition, "ALTER TABLE");
- /* Find or create work queue entry for this table */
+ CloneFkReferencing(pg_constraint, rel, partition,
+ list_make1_oid(constrOid),
+ &cloned);
+
+ heap_close(partition, NoLock);
+ }
+ heap_close(pg_constraint, RowExclusiveLock);
+
+ foreach(cell, cloned)
+ {
+ ClonedConstraint *cc = (ClonedConstraint *) lfirst(cell);
+ Relation partition = heap_open(cc->relid, lockmode);
+ AlteredTableInfo *childtab;
+ NewConstraint *newcon;
+
+ /* Find or create work queue entry for this partition */
childtab = ATGetQueueEntry(wqueue, partition);
- childAddr =
- ATAddForeignKeyConstraint(wqueue, childtab, partition,
- fkconstraint, constrOid,
- recurse, true, lockmode);
+ newcon = (NewConstraint *) palloc0(sizeof(NewConstraint));
+ newcon->name = cc->constraint->conname;
+ newcon->contype = CONSTR_FOREIGN;
+ newcon->refrelid = cc->refrelid;
+ newcon->refindid = cc->conindid;
+ newcon->conid = cc->conid;
+ newcon->qual = (Node *) fkconstraint;
- /* Record this constraint as dependent on the parent one */
- recordDependencyOn(&childAddr, &address, DEPENDENCY_INTERNAL_AUTO);
+ childtab->constraints = lappend(childtab->constraints, newcon);
- heap_close(partition, NoLock);
+ heap_close(partition, lockmode);
}
}
ALTER TABLE fk_partitioned_fk ATTACH PARTITION fk_partitioned_fk_2
FOR VALUES IN (1600);
-- leave these tables around intentionally
+-- Test creating a constraint at the parent that already exists in partitions.
+-- There should be no duplicated constraints, and attempts to drop the
+-- constraint in partitions should raise appropriate errors.
+create schema fkpart0
+ create table pkey (a int primary key)
+ create table fk_part (a int) partition by list (a)
+ create table fk_part_1 partition of fk_part
+ (foreign key (a) references fkpart0.pkey) for values in (1)
+ create table fk_part_23 partition of fk_part
+ (foreign key (a) references fkpart0.pkey) for values in (2, 3)
+ partition by list (a)
+ create table fk_part_23_2 partition of fk_part_23 for values in (2);
+alter table fkpart0.fk_part add foreign key (a) references fkpart0.pkey;
+\d fkpart0.fk_part_1 \\ -- should have only one FK
+ Table "fkpart0.fk_part_1"
+ Column | Type | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ a | integer | | |
+Partition of: fkpart0.fk_part FOR VALUES IN (1)
+Foreign-key constraints:
+ "fk_part_1_a_fkey" FOREIGN KEY (a) REFERENCES fkpart0.pkey(a)
+
+alter table fkpart0.fk_part_1 drop constraint fk_part_1_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_1_a_fkey" of relation "fk_part_1"
+\d fkpart0.fk_part_23 \\ -- should have only one FK
+ Partitioned table "fkpart0.fk_part_23"
+ Column | Type | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ a | integer | | |
+Partition of: fkpart0.fk_part FOR VALUES IN (2, 3)
+Partition key: LIST (a)
+Foreign-key constraints:
+ "fk_part_23_a_fkey" FOREIGN KEY (a) REFERENCES fkpart0.pkey(a)
+Number of partitions: 1 (Use \d+ to list them.)
+
+\d fkpart0.fk_part_23_2 \\ -- should have only one FK
+ Table "fkpart0.fk_part_23_2"
+ Column | Type | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ a | integer | | |
+Partition of: fkpart0.fk_part_23 FOR VALUES IN (2)
+Foreign-key constraints:
+ "fk_part_23_a_fkey" FOREIGN KEY (a) REFERENCES fkpart0.pkey(a)
+
+alter table fkpart0.fk_part_23 drop constraint fk_part_23_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_23_a_fkey" of relation "fk_part_23"
+alter table fkpart0.fk_part_23_2 drop constraint fk_part_23_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_23_a_fkey" of relation "fk_part_23_2"
+create table fkpart0.fk_part_4 partition of fkpart0.fk_part for values in (4);
+\d fkpart0.fk_part_4
+ Table "fkpart0.fk_part_4"
+ Column | Type | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ a | integer | | |
+Partition of: fkpart0.fk_part FOR VALUES IN (4)
+Foreign-key constraints:
+ "fk_part_a_fkey" FOREIGN KEY (a) REFERENCES fkpart0.pkey(a)
+
+alter table fkpart0.fk_part_4 drop constraint fk_part_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_a_fkey" of relation "fk_part_4"
+create table fkpart0.fk_part_56 partition of fkpart0.fk_part
+ for values in (5,6) partition by list (a);
+create table fkpart0.fk_part_56_5 partition of fkpart0.fk_part_56
+ for values in (5);
+\d fkpart0.fk_part_56
+ Partitioned table "fkpart0.fk_part_56"
+ Column | Type | Collation | Nullable | Default
+--------+---------+-----------+----------+---------
+ a | integer | | |
+Partition of: fkpart0.fk_part FOR VALUES IN (5, 6)
+Partition key: LIST (a)
+Foreign-key constraints:
+ "fk_part_a_fkey" FOREIGN KEY (a) REFERENCES fkpart0.pkey(a)
+Number of partitions: 1 (Use \d+ to list them.)
+
+alter table fkpart0.fk_part_56 drop constraint fk_part_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_a_fkey" of relation "fk_part_56"
+alter table fkpart0.fk_part_56_5 drop constraint fk_part_a_fkey;
+ERROR: cannot drop inherited constraint "fk_part_a_fkey" of relation "fk_part_56_5"
+\set VERBOSITY terse \\ -- suppress cascade details
+drop schema fkpart0 cascade;
+NOTICE: drop cascades to 2 other objects
+\set VERBOSITY default
FOR VALUES IN (1600);
-- leave these tables around intentionally
+
+-- Test creating a constraint at the parent that already exists in partitions.
+-- There should be no duplicated constraints, and attempts to drop the
+-- constraint in partitions should raise appropriate errors.
+create schema fkpart0
+ create table pkey (a int primary key)
+ create table fk_part (a int) partition by list (a)
+ create table fk_part_1 partition of fk_part
+ (foreign key (a) references fkpart0.pkey) for values in (1)
+ create table fk_part_23 partition of fk_part
+ (foreign key (a) references fkpart0.pkey) for values in (2, 3)
+ partition by list (a)
+ create table fk_part_23_2 partition of fk_part_23 for values in (2);
+
+alter table fkpart0.fk_part add foreign key (a) references fkpart0.pkey;
+\d fkpart0.fk_part_1 \\ -- should have only one FK
+alter table fkpart0.fk_part_1 drop constraint fk_part_1_a_fkey;
+
+\d fkpart0.fk_part_23 \\ -- should have only one FK
+\d fkpart0.fk_part_23_2 \\ -- should have only one FK
+alter table fkpart0.fk_part_23 drop constraint fk_part_23_a_fkey;
+alter table fkpart0.fk_part_23_2 drop constraint fk_part_23_a_fkey;
+
+create table fkpart0.fk_part_4 partition of fkpart0.fk_part for values in (4);
+\d fkpart0.fk_part_4
+alter table fkpart0.fk_part_4 drop constraint fk_part_a_fkey;
+
+create table fkpart0.fk_part_56 partition of fkpart0.fk_part
+ for values in (5,6) partition by list (a);
+create table fkpart0.fk_part_56_5 partition of fkpart0.fk_part_56
+ for values in (5);
+\d fkpart0.fk_part_56
+alter table fkpart0.fk_part_56 drop constraint fk_part_a_fkey;
+alter table fkpart0.fk_part_56_5 drop constraint fk_part_a_fkey;
+
+\set VERBOSITY terse \\ -- suppress cascade details
+drop schema fkpart0 cascade;
+\set VERBOSITY default
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