On 06/04/2013 05:27 AM, Peter Geoghegan wrote: > On Mon, Jun 3, 2013 at 5:03 AM, Craig Ringer <cr...@2ndquadrant.com> wrote: >> I've seen cases on Stack Overflow and elsewhere in which disk merge >> sorts perform vastly better than in-memory quicksort, so the user >> benefited from greatly *lowering* work_mem. > I've heard of that happening on Oracle, when the external sort is > capable of taking advantage of I/O parallelism, but I have a pretty > hard time believing that it could happen with Postgres under any > circumstances. IIRC it's usually occurred with very expensive comparison operations.
I'll see if I can find one of the SO cases. -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
