On Wed, Aug 6, 2014 at 10:36 PM, Peter Geoghegan <pg@heroku.com> wrote:
> This *almost* applies to patched Postgres if you pick a benchmark that
> is very sympathetic to my patch. To my surprise, work_mem = '10MB'
> (which results in an external tape sort) is sometimes snapping at the
> heels of a work_mem = '5GB' setting (which results in an in-memory
> quicksort).
Note that this was with a default temp_tablespaces setting that wrote
temp files on my home partition/SSD. With a /dev/shm/ temp tablespace,
tape sort edges ahead, and has a couple of hundred milliseconds on
quicksort for this test case. It's actually faster.
--
Peter Geoghegan