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Ensure correct lock level is used in ALTER ... RENAME

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Commit 1b5d797cd4 intended to relax the lock level used to rename
indexes, but inadvertently allowed *any* relation to be renamed with a
lowered lock level, as long as the command is spelled ALTER INDEX.
That's undesirable for other relation types, so retry the operation with
the higher lock if the relation turns out not to be an index.

After this fix, ALTER INDEX <sometable> RENAME will require access
exclusive lock, which it didn't before.

Author: Nathan Bossart <bossartn@amazon.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reported-by: Onder Kalaci <onderk@microsoft.com>
Discussion: https://postgr.es/m/PH0PR21MB1328189E2821CDEC646F8178D8AE9@PH0PR21MB1328.namprd21.prod.outlook.com
This commit is contained in:
Alvaro Herrera 2021-10-19 19:08:45 -03:00
parent 4438eb4a49
commit c2c618ff11
No known key found for this signature in database
GPG Key ID: 1C20ACB9D5C564AE
3 changed files with 127 additions and 14 deletions
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62
src/backend/commands/tablecmds.c
View File

@ -3735,7 +3735,7 @@ RenameConstraint(RenameStmt *stmt)
ObjectAddress
RenameRelation(RenameStmt *stmt)
{
bool is_index = stmt->renameType == OBJECT_INDEX;
bool is_index_stmt = stmt->renameType == OBJECT_INDEX;
Oid relid;
ObjectAddress address;
@ -3745,24 +3745,48 @@ RenameRelation(RenameStmt *stmt)
* end of transaction.
*
* Lock level used here should match RenameRelationInternal, to avoid lock
* escalation.
* escalation. However, because ALTER INDEX can be used with any relation
* type, we mustn't believe without verification.
*/
relid = RangeVarGetRelidExtended(stmt->relation,
is_index ? ShareUpdateExclusiveLock : AccessExclusiveLock,
stmt->missing_ok ? RVR_MISSING_OK : 0,
RangeVarCallbackForAlterRelation,
(void *) stmt);
if (!OidIsValid(relid))
for (;;)
{
ereport(NOTICE,
(errmsg("relation \"%s\" does not exist, skipping",
stmt->relation->relname)));
return InvalidObjectAddress;
LOCKMODE lockmode;
char relkind;
bool obj_is_index;
lockmode = is_index_stmt ? ShareUpdateExclusiveLock : AccessExclusiveLock;
relid = RangeVarGetRelidExtended(stmt->relation, lockmode,
stmt->missing_ok ? RVR_MISSING_OK : 0,
RangeVarCallbackForAlterRelation,
(void *) stmt);
if (!OidIsValid(relid))
{
ereport(NOTICE,
(errmsg("relation \"%s\" does not exist, skipping",
stmt->relation->relname)));
return InvalidObjectAddress;
}
/*
* We allow mismatched statement and object types (e.g., ALTER INDEX
* to rename a table), but we might've used the wrong lock level. If
* that happens, retry with the correct lock level. We don't bother
* if we already acquired AccessExclusiveLock with an index, however.
*/
relkind = get_rel_relkind(relid);
obj_is_index = (relkind == RELKIND_INDEX ||
relkind == RELKIND_PARTITIONED_INDEX);
if (obj_is_index || is_index_stmt == obj_is_index)
break;
UnlockRelationOid(relid, lockmode);
is_index_stmt = obj_is_index;
}
/* Do the work */
RenameRelationInternal(relid, stmt->newname, false, is_index);
RenameRelationInternal(relid, stmt->newname, false, is_index_stmt);
ObjectAddressSet(address, RelationRelationId, relid);
@ -3810,6 +3834,16 @@ RenameRelationInternal(Oid myrelid, const char *newrelname, bool is_internal, bo
errmsg("relation \"%s\" already exists",
newrelname)));
/*
* RenameRelation is careful not to believe the caller's idea of the
* relation kind being handled. We don't have to worry about this, but
* let's not be totally oblivious to it. We can process an index as
* not-an-index, but not the other way around.
*/
Assert(!is_index ||
is_index == (targetrelation->rd_rel->relkind == RELKIND_INDEX ||
targetrelation->rd_rel->relkind == RELKIND_PARTITIONED_INDEX));
/*
* Update pg_class tuple with new relname. (Scribbling on reltup is OK
* because it's a copy...)

48
src/test/regress/expected/alter_table.out
View File

@ -232,6 +232,54 @@ SET ROLE regress_alter_table_user1;
ALTER INDEX onek_unique1 RENAME TO fail; -- permission denied
ERROR: must be owner of index onek_unique1
RESET ROLE;
-- rename statements with mismatching statement and object types
CREATE TABLE alter_idx_rename_test (a INT);
CREATE INDEX alter_idx_rename_test_idx ON alter_idx_rename_test (a);
CREATE TABLE alter_idx_rename_test_parted (a INT) PARTITION BY LIST (a);
CREATE INDEX alter_idx_rename_test_parted_idx ON alter_idx_rename_test_parted (a);
BEGIN;
ALTER INDEX alter_idx_rename_test RENAME TO alter_idx_rename_test_2;
ALTER INDEX alter_idx_rename_test_parted RENAME TO alter_idx_rename_test_parted_2;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
relation | mode
--------------------------------+---------------------
alter_idx_rename_test_2 | AccessExclusiveLock
alter_idx_rename_test_parted_2 | AccessExclusiveLock
(2 rows)
COMMIT;
BEGIN;
ALTER INDEX alter_idx_rename_test_idx RENAME TO alter_idx_rename_test_idx_2;
ALTER INDEX alter_idx_rename_test_parted_idx RENAME TO alter_idx_rename_test_parted_idx_2;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
relation | mode
------------------------------------+--------------------------
alter_idx_rename_test_idx_2 | ShareUpdateExclusiveLock
alter_idx_rename_test_parted_idx_2 | ShareUpdateExclusiveLock
(2 rows)
COMMIT;
BEGIN;
ALTER TABLE alter_idx_rename_test_idx_2 RENAME TO alter_idx_rename_test_idx_3;
ALTER TABLE alter_idx_rename_test_parted_idx_2 RENAME TO alter_idx_rename_test_parted_idx_3;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
relation | mode
------------------------------------+---------------------
alter_idx_rename_test_idx_3 | AccessExclusiveLock
alter_idx_rename_test_parted_idx_3 | AccessExclusiveLock
(2 rows)
COMMIT;
DROP TABLE alter_idx_rename_test_2;
-- renaming views
CREATE VIEW attmp_view (unique1) AS SELECT unique1 FROM tenk1;
ALTER TABLE attmp_view RENAME TO attmp_view_new;

31
src/test/regress/sql/alter_table.sql
View File

@ -227,6 +227,37 @@ SET ROLE regress_alter_table_user1;
ALTER INDEX onek_unique1 RENAME TO fail; -- permission denied
RESET ROLE;
-- rename statements with mismatching statement and object types
CREATE TABLE alter_idx_rename_test (a INT);
CREATE INDEX alter_idx_rename_test_idx ON alter_idx_rename_test (a);
CREATE TABLE alter_idx_rename_test_parted (a INT) PARTITION BY LIST (a);
CREATE INDEX alter_idx_rename_test_parted_idx ON alter_idx_rename_test_parted (a);
BEGIN;
ALTER INDEX alter_idx_rename_test RENAME TO alter_idx_rename_test_2;
ALTER INDEX alter_idx_rename_test_parted RENAME TO alter_idx_rename_test_parted_2;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
COMMIT;
BEGIN;
ALTER INDEX alter_idx_rename_test_idx RENAME TO alter_idx_rename_test_idx_2;
ALTER INDEX alter_idx_rename_test_parted_idx RENAME TO alter_idx_rename_test_parted_idx_2;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
COMMIT;
BEGIN;
ALTER TABLE alter_idx_rename_test_idx_2 RENAME TO alter_idx_rename_test_idx_3;
ALTER TABLE alter_idx_rename_test_parted_idx_2 RENAME TO alter_idx_rename_test_parted_idx_3;
SELECT relation::regclass, mode FROM pg_locks
WHERE pid = pg_backend_pid() AND locktype = 'relation'
AND relation::regclass::text LIKE 'alter\_idx%'
ORDER BY relation::regclass::text;
COMMIT;
DROP TABLE alter_idx_rename_test_2;
-- renaming views
CREATE VIEW attmp_view (unique1) AS SELECT unique1 FROM tenk1;
ALTER TABLE attmp_view RENAME TO attmp_view_new;