Re: WIP - Add ability to constrain backend temporary file space

Mark,

> I got to wonder how hard this would be to do in Postgres, and attached
> is my (WIP) attempt. It provides a guc (max_temp_files_size) to limit
> the size of all temp files for a backend and amends fd.c cancel
> execution if the total size of temporary files exceeds this.

First, are we just talking about pgsql_tmp here, or the pg_temp
tablespace? That is, just sort/hash files, or temporary tables as well?

Second, the main issue with these sorts of macro-counters has generally
been their locking effect on concurrent activity. Have you been able to
run any tests which try to run lots of small externally-sorted queries
at once on a multi-core machine, and checked the effect on throughput?

--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com