Answered my own question. Cranking work_mem up to 350MB revealed that the in-memory sort requires more memory than the disk sort. On Wed, Aug 18, 2010 at 10:23 PM, Samuel Gendler <sgendler@xxxxxxxxxxxxxxxx> wrote: > I've got this explain: http://explain.depesz.com/s/Xh9 > > And these settings: > default_statistics_target = 50 # pgtune wizard 2010-08-17 > maintenance_work_mem = 1GB # pgtune wizard 2010-08-17 > constraint_exclusion = on # pgtune wizard 2010-08-17 > checkpoint_completion_target = 0.9 # pgtune wizard 2010-08-17 > effective_cache_size = 36GB # sam > work_mem = 288MB # pgtune wizard 2010-08-17 > wal_buffers = 8MB # pgtune wizard 2010-08-17 > #checkpoint_segments = 16 # pgtune wizard 2010-08-17 > checkpoint_segments = 30 # sam > shared_buffers = 11GB # pgtune wizard 2010-08-17 > max_connections = 80 # pgtune wizard 2010-08-17 > cpu_tuple_cost = 0.0030 # sam > cpu_index_tuple_cost = 0.0010 # sam > cpu_operator_cost = 0.0005 # sam > #random_page_cost = 2.0 # sam > > I'm not understanding why it is sorting on disk if it would fit within > a work_mem segment - by a fairly wide margin. Is there something else > I can do to get that sort to happen in memory? > -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
