Scott Rankin <srankin@xxxxxxxxx> writes: > Iâ??m trying to track down why some queries on my database system are intermittently much slower than usual. I have some queries that run, on average, 2-3ms, and they run at a rate of about 10-20 queries/second. However, every 3-5 seconds, one of the queries will be 500-100ms. This is making the average query time turn out to be closer to 20ms, with a very large standard deviation. > This happens to a number of otherwise very fast queries, and Iâ??m trying to trace the reason. Iâ??ve turned on lock logging and checkpoint logging, and this behavior happens whether or not a checkpoint is occurring. There are no lock waits happening in the system either. I doubt you've proved that --- log_lock_waits will only report on waits longer than deadlock_timeout, which you don't appear to have changed from its default of 1 sec. If you're trying to capture events that last a few hundred msec, you're going to need to reduce deadlock_timeout to maybe 100ms. It would help to know more about what the queries are, too. The cause might be something like GIN index pending-list cleanup but we can't tell on the basis of this much info. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
