Re: Occasional timeouts on TRUNCATE and simple INSERTs

On Tue, Dec 11, 2012 at 1:19 PM, Osborn, Jeff <jeosborn(at)akamai(dot)com> wrote:
> I am seeing some strange performance on a new pg9.1 instance. We are seeing occasional statement timeouts on some TRUNCATEs and INSERTs. In both cases, the statements are quite simple:
> - TRUNCATE schema.table;
> - INSERT INTO schema.table VALUES ($1,2,$2,'');
>
> Sometimes these will succeed. Occasionally I see timeouts. The statement_timeout is set to 60 seconds. These tables are not particularly large; in the case of the insert, the table only has three rows.

A most common case is when backup (pg_dump*) is running TRUNCATE has
to wait for it because it acquires an access exclusive lock on a table
and all other queries including INSERT have to wait for the TRUNCATE.
Check the backup case first.

> Our previous Postgresql 8.2 instance did not have this problem.

This is strange for me.

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