blocking automatic vacuum

Hi,

last ween i've seen a blocking "automatic vacuum".
as i understood, this is not supposed to happen. in the past i saw vacuum processes disappear, in case of the need of a lock.


this is the relvant extract from the log and the database:
2010-06-18 18:33:36.011 CEST    172.19.5.34(57414)      gc:29274        143897560       LOG:  process 29274 still waiting for RowExclusiveLock on relation 42964239 of database 19759903 after 1002.601 ms
...
2010-06-18 19:23:43.898 CEST            :20892  0       LOG:  automatic vacuum of table "gd.pg_toast.pg_toast_42964236": index scans: 1
        pages: 1469113 removed, 288899 remain
        tuples: 369645 removed, 396719 remain
        system usage: CPU 5.46s/0.85u sec elapsed 13785.76 sec
2010-06-18 19:23:43.899 CEST    172.19.5.22(45561)      gc:315  143897590       LOG:  process 315 acquired RowExclusiveLock on relation 42964239 of database 19759903 after 3007903.169 ms
2010-06-18 19:23:43.920 CEST    172.19.5.22(45561)      gc:315  143897590       LOG:  duration: 3007924.883 ms  execute <unnamed>: insert into SHARED_GAMESET .....

gd=# select oid,* from pg_class where reltoastrelid=42964239;
    relname     | relnamespace | reltype  | relowner | relam | relfilenode | reltablespace | relpages |  reltuples  | reltoastrelid | reltoastidxid | relhasindex | relisshared | relistemp | relkind | relnatts | relchecks | rel
hasoids | relhaspkey | relhasrules | relhastriggers | relhassubclass | relfrozenxid |                 relacl                 | reloptions
----------------+--------------+----------+----------+-------+-------------+---------------+----------+-------------+---------------+---------------+-------------+-------------+-----------+---------+----------+-----------+----
--------+------------+-------------+----------------+----------------+--------------+----------------------------------------+------------
 shared_gameset |     19760303 | 42964238 |    16443 |     0 |    42964236 |             0 |   143715 | 1.96642e+06 |      42964239 |             0 | t           | f           | f         | r       |        4 |         0 | f 
        | t          | f           | f              | f              |    101290258 | {gdadm=arwdDxt/gdadm,gc=arwdDxt/gdadm} |
(1 row)



So what's this?
from my point of view the vacuum blocked inserts on this table for about 50 minutes.
Is this a bug?
Or do yuo see here a configuration issue?

best regards,
Uwe

Uwe Bartels
Systemarchitect - Freelancer
mailto: uwe.bartels at gmail.com