Jon Nelson <jnelson+pgsql@xxxxxxxxxxx> writes: > This is on PG 8.4.8 on Linux, 16GB of "real" RAM. > Most recently, I enabled trace_sort, disabled hash aggregation[1], and > set a large work_mem (normally very small, in this case I tried > anything from 8MB to 256MB. I even tried 1GB and 2GB). FWIW, I think hash aggregation is your best shot at getting reasonable performance. Sorting 175GB of data is going to hurt no matter what. If the grouped table amounts to 5GB, I wouldn't have expected the hash table to be more than maybe 2-3X that size (although this does depend on what aggregates you're running...). Letting the hash aggregation have all your RAM might be the best answer. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
