Hi,
While studying and hacking on the parenting constraint issue, I found an
incoherent piece of code leading to badly chosen fk name. If a constraint
name collision is detected, while choosing a new name for the constraint,
the code uses fkconstraint->fk_attrs which is not yet populated:
/* No dice. Set up to create our own constraint */
fkconstraint = makeNode(Constraint);
if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
RelationGetRelid(partRel),
NameStr(constrForm->conname)))
fkconstraint->conname =
ChooseConstraintName(RelationGetRelationName(partRel),
ChooseForeignKeyConstraintNameAddition(
fkconstraint->fk_attrs), // <= WOO000OPS
"fkey",
RelationGetNamespace(partRel), NIL);
else
fkconstraint->conname = pstrdup(NameStr(constrForm->conname));
fkconstraint->fk_upd_action = constrForm->confupdtype;
fkconstraint->fk_del_action = constrForm->confdeltype;
fkconstraint->deferrable = constrForm->condeferrable;
fkconstraint->initdeferred = constrForm->condeferred;
fkconstraint->fk_matchtype = constrForm->confmatchtype;
for (int i = 0; i < numfks; i++)
{
Form_pg_attribute att;
att = TupleDescAttr(RelationGetDescr(partRel),
mapped_conkey[i] - 1);
fkconstraint->fk_attrs = lappend(fkconstraint->fk_attrs, // <= POPULATING
makeString(NameStr(att->attname)));
}
The following SQL script showcase the bad constraint name:
DROP TABLE IF EXISTS parent, child1;
CREATE TABLE parent (
id bigint NOT NULL default 1,
no_part smallint NOT NULL,
id_abc bigint,
CONSTRAINT dummy_constr FOREIGN KEY (id_abc, no_part)
REFERENCES parent(id, no_part) ON UPDATE RESTRICT ON DELETE RESTRICT,
PRIMARY KEY (id, no_part)
)
PARTITION BY LIST (no_part);
CREATE TABLE child1 (
id bigint NOT NULL default 1,
no_part smallint NOT NULL,
id_abc bigint,
PRIMARY KEY (id, no_part),
CONSTRAINT dummy_constr CHECK ((no_part = 1))
);
ALTER TABLE parent ATTACH PARTITION child1 FOR VALUES IN ('1');
SELECT conname
FROM pg_constraint
WHERE conrelid = 'child1'::regclass
AND contype = 'f';
DROP TABLE
CREATE TABLE
CREATE TABLE
ALTER TABLE
conname
--------------
child1__fkey
(1 row)
The resulting constraint name "child1__fkey" is missing the attributes name the
original code wanted to add. The expected name is "child1_id_abc_no_part_fkey".
Find in attachment a simple fix, moving the name assignation after the
FK attributes are populated.
Regards,
>From f1eeacb1eb3face38d76325666aff57019ef84c9 Mon Sep 17 00:00:00 2001
From: Jehan-Guillaume de Rorthais <[email protected]>
Date: Thu, 1 Sep 2022 17:41:55 +0200
Subject: [PATCH] Fix FK name when colliding during partition attachment
During ATLER TABLE ATTACH PARTITION, if the name of a parent's
foreign key constraint is already used on the partition, the code
try to choose another one before the FK attributes list has been
populated. The resulting constraint name was a strange
"<relname>__fkey" instead of "<relname>_<attrs>_fkey".
---
src/backend/commands/tablecmds.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index dacc989d85..53b0f3a9c1 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -10304,16 +10304,6 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
/* No dice. Set up to create our own constraint */
fkconstraint = makeNode(Constraint);
- if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
- RelationGetRelid(partRel),
- NameStr(constrForm->conname)))
- fkconstraint->conname =
- ChooseConstraintName(RelationGetRelationName(partRel),
- ChooseForeignKeyConstraintNameAddition(fkconstraint->fk_attrs),
- "fkey",
- RelationGetNamespace(partRel), NIL);
- else
- fkconstraint->conname = pstrdup(NameStr(constrForm->conname));
fkconstraint->fk_upd_action = constrForm->confupdtype;
fkconstraint->fk_del_action = constrForm->confdeltype;
fkconstraint->deferrable = constrForm->condeferrable;
@@ -10328,6 +10318,16 @@ CloneFkReferencing(List **wqueue, Relation parentRel, Relation partRel)
fkconstraint->fk_attrs = lappend(fkconstraint->fk_attrs,
makeString(NameStr(att->attname)));
}
+ if (ConstraintNameIsUsed(CONSTRAINT_RELATION,
+ RelationGetRelid(partRel),
+ NameStr(constrForm->conname)))
+ fkconstraint->conname =
+ ChooseConstraintName(RelationGetRelationName(partRel),
+ ChooseForeignKeyConstraintNameAddition(fkconstraint->fk_attrs),
+ "fkey",
+ RelationGetNamespace(partRel), NIL);
+ else
+ fkconstraint->conname = pstrdup(NameStr(constrForm->conname));
indexOid = constrForm->conindid;
constrOid =
--
2.37.2
