2014-10-05 21:57 GMT+03:00 Andrey Lizenko <lizenk...@gmail.com>: > Increasing of 'effective_cache_size' leads to similar thing with > mergejoin, > other options (work_mem, shared_buffers. etc) do not change anything. >
I think increasing `work_mem` should have effects, as plan with `Nested Loop` is using disk-based sort. Increase it till you'll stop seeing `external sort` in the EXPLAIN output. Something like '10MB' should do. Also, it'd be handy if you could provide `EXPLAIN (analyze, buffers)` output along with the results of these queries: SELECT name,setting,source FROM pg_settings WHERE name ~ 'cost' AND NOT name ~ 'vacuum'; SELECT name,setting,source FROM pg_settings WHERE NOT source IN ('default','override'); And describe your setup: what OS? how much RAM? what kind of disks? RAID? -- Victor Y. Yegorov