diff options
| author | Peter Eisentraut <peter@eisentraut.org> | 2025-08-27 16:46:51 +0200 |
|---|---|---|
| committer | Peter Eisentraut <peter@eisentraut.org> | 2025-08-27 17:46:26 +0200 |
| commit | e36fa9319b1366ee0194e130a9a77c4af7ee1853 (patch) | |
| tree | 26fdda6425911f0f5573bb47fb500a287f49035e /src | |
| parent | 990c8db1827c0c96fb20cb4fbfcc9690e9b45e15 (diff) | |
Improve objectNamesToOids() comment
Commit d31bbfb6590 removed the comment at objectNamesToOids() that
there is no locking, because that commit added locking. But to fix
all the problems, we'd still need a stronger lock. So put the comment
back with more a detailed explanation.
Co-authored-by: Noah Misch <noah@leadboat.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://www.postgresql.org/message-id/flat/bf72b82c-124d-4efa-a484-bb928e9494e4@eisentraut.org
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/catalog/aclchk.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c index 9ca8a88dc91..24948c1f05e 100644 --- a/src/backend/catalog/aclchk.c +++ b/src/backend/catalog/aclchk.c @@ -659,6 +659,20 @@ ExecGrantStmt_oids(InternalGrant *istmt) * objectNamesToOids * * Turn a list of object names of a given type into an Oid list. + * + * XXX This function intentionally takes only an AccessShareLock. In the face + * of concurrent DDL, we might easily latch onto an old version of an object, + * causing the GRANT or REVOKE statement to fail. But it does prevent the + * object from disappearing altogether. To do better, we would need to use a + * self-exclusive lock, perhaps ShareUpdateExclusiveLock, here and before + * *every* CatalogTupleUpdate() of a row that GRANT/REVOKE can affect. + * Besides that additional work, this could have operational costs. For + * example, it would make GRANT ALL TABLES IN SCHEMA terminate every + * autovacuum running in the schema and consume a shared lock table entry per + * table in the schema. The user-visible benefit of that additional work is + * just changing "ERROR: tuple concurrently updated" to blocking. That's not + * nothing, but it might not outweigh autovacuum termination and lock table + * consumption spikes. */ static List * objectNamesToOids(ObjectType objtype, List *objnames, bool is_grant) |