From: Tom Lane Date: Thu, 3 Jul 2025 17:46:07 +0000 (-0400) Subject: Obtain required table lock during cross-table updates, redux. X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6d4395b4021d5f2640f2aadece1dad650b1e7037;p=thirdparty%2Fpostgresql.git Obtain required table lock during cross-table updates, redux. Commits 8319e5cb5 et al missed the fact that ATPostAlterTypeCleanup contains three calls to ATPostAlterTypeParse, and the other two also need protection against passing a relid that we don't yet have lock on. Add similar logic to those code paths, and add some test cases demonstrating the need for it. In v18 and master, the test cases demonstrate that there's a behavioral discrepancy between stored generated columns and virtual generated columns: we disallow changing the expression of a stored column if it's used in any composite-type columns, but not that of a virtual column. Since the expression isn't actually relevant to either sort of composite-type usage, this prohibition seems unnecessary; but changing it is a matter for separate discussion. For now we are just documenting the existing behavior. Reported-by: jian he Author: jian he Reviewed-by: Tom Lane Discussion: CACJufxGKJtGNRRSXfwMW9SqVOPEMdP17BJ7DsBf=tNsv9pWU9g@mail.gmail.com Backpatch-through: 13 --- diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 81ab12df60c..fb64730a7e1 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -13926,6 +13926,14 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode) Oid relid; relid = IndexGetRelation(oldId, false); + + /* + * As above, make sure we have lock on the index's table if it's not + * the same table. + */ + if (relid != tab->relid) + LockRelationOid(relid, AccessExclusiveLock); + ATPostAlterTypeParse(oldId, relid, InvalidOid, (char *) lfirst(def_item), wqueue, lockmode, tab->rewrite); @@ -13942,6 +13950,20 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode) Oid relid; relid = StatisticsGetRelation(oldId, false); + + /* + * As above, make sure we have lock on the statistics object's table + * if it's not the same table. However, we take + * ShareUpdateExclusiveLock here, aligning with the lock level used in + * CreateStatistics and RemoveStatisticsById. + * + * CAUTION: this should be done after all cases that grab + * AccessExclusiveLock, else we risk causing deadlock due to needing + * to promote our table lock. + */ + if (relid != tab->relid) + LockRelationOid(relid, ShareUpdateExclusiveLock); + ATPostAlterTypeParse(oldId, relid, InvalidOid, (char *) lfirst(def_item), wqueue, lockmode, tab->rewrite); diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 9d90d5505a8..7cebd50a673 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -4620,6 +4620,14 @@ 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 +alter table atref drop constraint atref_b_check; +create statistics atref_stat on ((b).a is not null) from atref; +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 statistics atref_stat; +create index atref_idx on atref (((b).a)); +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 diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated.out index a1f67abb688..f7c867e054c 100644 --- a/src/test/regress/expected/generated.out +++ b/src/test/regress/expected/generated.out @@ -1190,6 +1190,30 @@ Inherits: gtest30 ALTER TABLE gtest30_1 ALTER COLUMN b DROP EXPRESSION; -- error ERROR: cannot drop generation expression from inherited column +-- composite type dependencies +CREATE TABLE gtest31_1 (a int, b text GENERATED ALWAYS AS ('hello') STORED, c text); +CREATE TABLE gtest31_2 (x int, y gtest31_1); +ALTER TABLE gtest31_1 ALTER COLUMN b TYPE varchar; -- fails +ERROR: cannot alter table "gtest31_1" because column "gtest31_2.y" uses its row type +-- bug #18970: these cases are unsupported, but make sure they fail cleanly +ALTER TABLE gtest31_2 ADD CONSTRAINT cc CHECK ((y).b IS NOT NULL); +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello1'); +ERROR: cannot alter table "gtest31_1" because column "gtest31_2.y" uses its row type +ALTER TABLE gtest31_2 DROP CONSTRAINT cc; +CREATE STATISTICS gtest31_2_stat ON ((y).b is not null) FROM gtest31_2; +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello2'); +ERROR: cannot alter table "gtest31_1" because column "gtest31_2.y" uses its row type +DROP STATISTICS gtest31_2_stat; +CREATE INDEX gtest31_2_y_idx ON gtest31_2(((y).b)); +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello3'); +ERROR: cannot alter table "gtest31_1" because column "gtest31_2.y" uses its row type +DROP TABLE gtest31_1, gtest31_2; +-- Check it for a partitioned table, too +CREATE TABLE gtest31_1 (a int, b text GENERATED ALWAYS AS ('hello') STORED, c text) PARTITION BY LIST (a); +CREATE TABLE gtest31_2 (x int, y gtest31_1); +ALTER TABLE gtest31_1 ALTER COLUMN b TYPE varchar; -- fails +ERROR: cannot alter table "gtest31_1" because column "gtest31_2.y" uses its row type +DROP TABLE gtest31_1, gtest31_2; -- triggers CREATE TABLE gtest26 ( a int PRIMARY KEY, diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql index df08e93b70f..16ed0782fa1 100644 --- a/src/test/regress/sql/alter_table.sql +++ b/src/test/regress/sql/alter_table.sql @@ -3032,6 +3032,14 @@ drop table attbl, atref; 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 +alter table atref drop constraint atref_b_check; + +create statistics atref_stat on ((b).a is not null) from atref; +alter table attbl alter column a type numeric; -- someday this should work +drop statistics atref_stat; + +create index atref_idx on atref (((b).a)); +alter table attbl alter column a type numeric; -- someday this should work drop table attbl, atref; /* End test case for bug #18970 */ diff --git a/src/test/regress/sql/generated.sql b/src/test/regress/sql/generated.sql index ba59325da87..2816ac4a74a 100644 --- a/src/test/regress/sql/generated.sql +++ b/src/test/regress/sql/generated.sql @@ -550,6 +550,31 @@ ALTER TABLE ONLY gtest30 ALTER COLUMN b DROP EXPRESSION; -- error \d gtest30_1 ALTER TABLE gtest30_1 ALTER COLUMN b DROP EXPRESSION; -- error +-- composite type dependencies +CREATE TABLE gtest31_1 (a int, b text GENERATED ALWAYS AS ('hello') STORED, c text); +CREATE TABLE gtest31_2 (x int, y gtest31_1); +ALTER TABLE gtest31_1 ALTER COLUMN b TYPE varchar; -- fails + +-- bug #18970: these cases are unsupported, but make sure they fail cleanly +ALTER TABLE gtest31_2 ADD CONSTRAINT cc CHECK ((y).b IS NOT NULL); +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello1'); +ALTER TABLE gtest31_2 DROP CONSTRAINT cc; + +CREATE STATISTICS gtest31_2_stat ON ((y).b is not null) FROM gtest31_2; +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello2'); +DROP STATISTICS gtest31_2_stat; + +CREATE INDEX gtest31_2_y_idx ON gtest31_2(((y).b)); +ALTER TABLE gtest31_1 ALTER COLUMN b SET EXPRESSION AS ('hello3'); + +DROP TABLE gtest31_1, gtest31_2; + +-- Check it for a partitioned table, too +CREATE TABLE gtest31_1 (a int, b text GENERATED ALWAYS AS ('hello') STORED, c text) PARTITION BY LIST (a); +CREATE TABLE gtest31_2 (x int, y gtest31_1); +ALTER TABLE gtest31_1 ALTER COLUMN b TYPE varchar; -- fails +DROP TABLE gtest31_1, gtest31_2; + -- triggers CREATE TABLE gtest26 ( a int PRIMARY KEY,