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Prevent setting a column as identity if its not-null constraint is invalid

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We don't allow null values to appear in identity-generated columns in
other ways, so we shouldn't let unvalidated not-null constraints do it
either.  Oversight in commit a379061a22.

Author: jian he <jian.universality@gmail.com>
Backpatch-through: 18
Discussion: https://postgr.es/m/CACJufxGQM_+vZoYJMaRoZfNyV=L2jxosjv_0TLAScbuLJXWRfQ@mail.gmail.com
This commit is contained in:
Álvaro Herrera
2025-11-03 15:58:19 +01:00
parent f242dbcede
commit cf8be02253
3 changed files with 32 additions and 0 deletions
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25
src/backend/commands/tablecmds.c
View File

@@ -8281,6 +8281,31 @@ ATExecAddIdentity(Relation rel, const char *colName,
errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
colName, RelationGetRelationName(rel))));
/*
* On the other hand, if a not-null constraint exists, then verify that
* it's compatible.
*/
if (attTup->attnotnull)
{
HeapTuple contup;
Form_pg_constraint conForm;
contup = findNotNullConstraintAttnum(RelationGetRelid(rel),
attnum);
if (!HeapTupleIsValid(contup))
elog(ERROR, "cache lookup failed for not-null constraint on column \"%s\" of relation \"%s\"",
colName, RelationGetRelationName(rel));
conForm = (Form_pg_constraint) GETSTRUCT(contup);
if (!conForm->convalidated)
ereport(ERROR,
errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("incompatible NOT VALID constraint \"%s\" on relation \"%s\"",
NameStr(conForm->conname), RelationGetRelationName(rel)),
errhint("You might need to validate it using %s.",
"ALTER TABLE ... VALIDATE CONSTRAINT"));
}
if (attTup->attidentity)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

4
src/test/regress/expected/constraints.out
View File

@@ -1404,6 +1404,10 @@ ALTER TABLE notnull_tbl1 ADD PRIMARY KEY (a);
ERROR: cannot create primary key on column "a"
DETAIL: The constraint "nn" on column "a" of table "notnull_tbl1", marked NOT VALID, is incompatible with a primary key.
HINT: You might need to validate it using ALTER TABLE ... VALIDATE CONSTRAINT.
-- cannot set column as generated-as-identity if it has an invalid not-null
ALTER TABLE notnull_tbl1 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
ERROR: incompatible NOT VALID constraint "nn" on relation "notnull_tbl1"
HINT: You might need to validate it using ALTER TABLE ... VALIDATE CONSTRAINT.
-- ALTER column SET NOT NULL validates an invalid constraint (but this fails
-- because of rows with null values)
ALTER TABLE notnull_tbl1 ALTER a SET NOT NULL;

3
src/test/regress/sql/constraints.sql
View File

@@ -832,6 +832,9 @@ ALTER TABLE notnull_tbl1 ADD CONSTRAINT nn NOT NULL a;
-- cannot add primary key on a column with an invalid not-null
ALTER TABLE notnull_tbl1 ADD PRIMARY KEY (a);
-- cannot set column as generated-as-identity if it has an invalid not-null
ALTER TABLE notnull_tbl1 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
-- ALTER column SET NOT NULL validates an invalid constraint (but this fails
-- because of rows with null values)
ALTER TABLE notnull_tbl1 ALTER a SET NOT NULL;