Re: transaction delays to apply

Tom Lane wrote:
> Nickolay <nitro(at)zhukcity(dot)ru> writes:
>
>> BUT it seems that rarely this transaction is being delayed to apply and
>> log entry is being inserted in wrong order:
>> ID timestamp
>> 1 2009-08-08 00:00:00.111
>> 2 2009-08-08 00:00:30.311
>> 3 2009-08-08 00:00:00.211
>> Yep, that's right - sometimes for 30 seconds or even more.
>>
>
> You haven't provided enough information to let anyone guess at the
> problem. Have you checked to see if one of the processes is blocking
> on a lock, or perhaps there's a sudden spike in system load, or what?
> Watching pg_stat_activity, pg_locks, and/or "vmstat 1" output during
> one of these events might help narrow down what's happening.
>
> regards, tom lane
>
>

The problem is that such thing happens very rare, and NOT at full load.
I can't monitor the system all the time. Is there any way to investigate
the situation by any of pgsql logs or enable something like full debug?
I do have a row-level lock (SELECT...FOR UPDATE) on another table during
this transaction, but one row are handled by not more than 2 processes
at once and it should be very quick (SELECT, parse data and UPDATE).
Thank you very much for you help!

Best regards, Nick.