Обсуждение: Re: PostgreSQL 9.2.3 performance problem caused Exclusive locks

2013-03-08 13:27:16 +0200 Emre Hasegeli <emre.hasegeli@tart.com.tr>:

> PostgreSQL writes several following logs during the problem which I never
> saw before 9.2.3:
>
> LOG:  process 4793 acquired ExclusiveLock on extension of relation
> 305605 of database 16396 after 2348.675 ms

I tried

* to downgrade to 9.2.2
* to disable autovacuum
* to disable synchronous commit
* to write less on the big tables
* to increase checkpoint segments
* to increase max connections
* to move pg_xlog to sepe

None of them helps to avoid downtimes. I could not find anything related
to it? Do you have any idea? Have you ever experience something like this?

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