Emre,
> > LOG: process 4793 acquired ExclusiveLock on extension of relation
> > 305605 of database 16396 after 2348.675 ms
The reason you're seeing that message is that you have log_lock_waits turned on.
That message says that some process waited for 2.3 seconds to get a lock for expanding the size of relation
16396/305605,which is most likely an index. This is most likely due to changes in your application, or an increase in
concurrentwrite activity.
--Josh