autovacuum and locks

Hi all,

recently our application was locked, and postgres shows several
processes in "LOCK TABLE waiting" state. Even the autovacuum process is
stalled.

The pg_locks table shows the following:

> SELECT pg_class.relname AS table, transaction, pid, mode, granted FROM
pg_locks, pg_class, pg_database WHERE pg_locks.relation = pg_class.oid
AND pg_locks.database = pg_database.oid;

pg_class 3389057 | 26130 | AccessShareLock
| t
pg_class_oid_index 3389057 | 26130 | AccessShareLock
| t
pg_locks 3389057 | 26130 | AccessShareLock
| t

cgreylist 3368984 | 10979 |
ShareUpdateExclusiveLock | t
cgreylist_pkey 3368984 | 10979 |
ShareUpdateExclusiveLock | t
cgreylist_extime_index 3368984 | 10979 |
ShareUpdateExclusiveLock | t
cgreylist_instance_sender_index 3368984 | 10979 |
ShareUpdateExclusiveLock | t
cgreylist_mtime_index 3368984 | 10979 |
ShareUpdateExclusiveLock | t

cgreylist 3368998 | 10980 | ExclusiveLock
| f

cgreylist 3369000 | 10984 | AccessShareLock
| t
cgreylist 3369000 | 10984 | RowExclusiveLock
| f # WHY?
cgreylist_extime_index 3369000 | 10984 | AccessShareLock
| t

cgreylist 3388458 | 10023 | ExclusiveLock
| f ?
cgreylist 3388420 | 10021 | ExclusiveLock
| f ?

Why cant postgres get the RowExclusiveLock in transaction 3369000?

I do not see any confliction lock types here - or do i miss something?

(we use postgresql-8.1 (8.1.8-1) on debian 4.0)

- Dietmar