On Wed, Jan 29, 2014 at 3:38 PM, Дмитрий Шалашов <skau...@gmail.com> wrote:
> "feed_user_id_added_idx2" btree (user_id, added DESC) WHERE active_id = > user_id AND type = 1 > ... > SELECT * FROM feed WHERE user_id = ? AND type = 1 AND active_id = user_id > ORDER BY added DESC LIMIT 31; > > But it doesn't use the last index. EXPLAIN shows this: > > Limit (cost=0.00..463.18 rows=31 width=50) > -> Index Scan Backward using feed_user_id_active_id_added_idx on > user_feed (cost=0.00..851.66 rows=57 width=50) > Index Cond: ((user_id = 7) AND (active_id = 7)) > Filter: (type = 1) > > So as we can see optimiser changes "active_id = user_id" to "active_id = > <whatever value user_id takes>". And it brokes my nice fast partial index :( > Can I do something here so optimiser would use the feed_user_id_added_idx2 > index? It's around ten times smaller than the 'generic' > feed_user_id_active_id_added_idx index. > How about "where user_id+0=?" Cheers, Jeff
