Re: strange pauses

Richard Huxton <dev@archonet.com> writes:
> Adrian Moisey wrote:
>> If I tail the logs, I see a steady stream of functions that took longer
>> then 5 seconds.  But every now and then I see nothing for 3 minutes and
>> after that a whole bunch (about 20 - 30) queries all finishing at the
>> same second.

> Search this list for references to "checkpoints". If you run
> vmstat/iostat for a bit you should see bursts of disk activity at those
> times.

A different line of thought is that something is taking out an exclusive
lock on a table that all these queries need.  If vmstat doesn't show any
burst of activity during these pauses, look into pg_locks.

            regards, tom lane