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Fix creation of duplicate foreign keys on partitions

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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
This commit is contained in:
Alvaro Herrera 2019-01-18 14:49:40 -03:00
parent fca6cabed1
commit 4dff8935fb
3 changed files with 152 additions and 12 deletions
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43
src/backend/commands/tablecmds.c
View File

@ -7751,31 +7751,50 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
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 */
childtab = ATGetQueueEntry(wqueue, partition);
childAddr =
ATAddForeignKeyConstraint(wqueue, childtab, partition,
fkconstraint, constrOid,
recurse, true, lockmode);
/* Record this constraint as dependent on the parent one */
recordDependencyOn(&childAddr, &address, DEPENDENCY_INTERNAL_AUTO);
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);
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;
childtab->constraints = lappend(childtab->constraints, newcon);
heap_close(partition, lockmode);
}
}
/*

83
src/test/regress/expected/foreign_key.out
View File

@ -1781,3 +1781,86 @@ INSERT INTO fk_notpartitioned_pk VALUES (1600, 601), (1600, 1601);
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
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
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

38
src/test/regress/sql/foreign_key.sql
View File

@ -1289,3 +1289,41 @@ 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
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