On Thu, Aug 28, 2014 at 11:50 AM, gmb <gmbou...@gmail.com> wrote: > Can somebody please confirm whether aggregate functions such as GROUP BY > should use indexes ?
Yes, if the planner deems it faster than other approaches. It can make wrong choices for many reasons, but usually when your planner tunables like random_page_cost, effective_cache_size aren't set appropriately. There's some advice here: https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server Just for the purpose of testing, you could try "set enable_sort=false" in your session and see if that makes it faster. On Thu, Aug 28, 2014 at 12:08 PM, gmb <gmbou...@gmail.com> wrote: > Sort Key: co_id, client_id, doc_no, Something went missing from this line... > Sort Method: external merge Disk: 80304kB Depends on your hardware and workloads, but more work_mem may also improve queries to avoid sorts and hashes needing to use disk. But beware, setting it too high may result in your server running out of memory. Regards, Marti -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
