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Obtain required table lock during cross-table constraint updates.

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Sometimes a table's constraint may depend on a column of another
table, so that we have to update the constraint when changing the
referenced column's type.  We need to have lock on the constraint's
table to do that.  ATPostAlterTypeCleanup believed that this case
was only possible for FOREIGN KEY constraints, but it's wrong at
least for CHECK and EXCLUDE constraints; and in general, we'd
probably need exclusive lock to alter any sort of constraint.
So just remove the contype check and acquire lock for any other
table.  This prevents a "you don't have lock" assertion failure,
though no ill effect is observed in production builds.

We'll error out later anyway because we don't presently support
physically altering column types within stored composite columns.
But the catalog-munging is basically all there, so we may as well
make that part work.

Bug: #18970
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Diagnosed-by: jian he <jian.universality@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/18970-a7d1cfe1f8d5d8d9@postgresql.org
Backpatch-through: 13
This commit is contained in:
Tom Lane
2025-06-29 13:56:03 -04:00
parent 6d12d5a433
commit 8319e5cb54
3 changed files with 27 additions and 10 deletions
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7
src/test/regress/expected/alter_table.out
View File

@@ -4745,6 +4745,13 @@ alter table attbl alter column p1 set data type bigint;
alter table atref alter column c1 set data type bigint;
drop table attbl, atref;
/* End test case for bug #17409 */
/* Test case for bug #18970 */
create table attbl(a int);
create table atref(b attbl check ((b).a is not null));
alter table attbl alter column a type numeric; -- someday this should work
ERROR: cannot alter table "attbl" because column "atref.b" uses its row type
drop table attbl, atref;
/* End test case for bug #18970 */
-- Test that ALTER TABLE rewrite preserves a clustered index
-- for normal indexes and indexes on constraints.
create table alttype_cluster (a int);

9
src/test/regress/sql/alter_table.sql
View File

@@ -3069,6 +3069,15 @@ drop table attbl, atref;
/* End test case for bug #17409 */
/* Test case for bug #18970 */
create table attbl(a int);
create table atref(b attbl check ((b).a is not null));
alter table attbl alter column a type numeric; -- someday this should work
drop table attbl, atref;
/* End test case for bug #18970 */
-- Test that ALTER TABLE rewrite preserves a clustered index
-- for normal indexes and indexes on constraints.
create table alttype_cluster (a int);