> > =# explain SELECT * FROM n_traf ORDER BY date_time DESC LIMIT 1; > > QUERY PLAN > --------------------------------------------------------------------------------------------------------- > > Limit (cost=824637.69..824637.69 rows=1 width=32) > > -> Sort (cost=824637.69..838746.44 rows=5643499 width=32) > > Sort Key: public.n_traf.date_time > > -> Result (cost=0.00..100877.99 rows=5643499 width=32) > > -> Append (cost= 0.00..100877.99 rows=5643499 width=32) > > -> Seq Scan on n_traf (cost=0.00..22.30 > > rows=1230 width=32) > > -> Seq Scan on n_traf_y2007m01 n_traf > > (cost=0.00..22.30 rows=1230 width=32) ... > > -> Seq Scan on n_traf_y2007m12 n_traf > > (cost=0.00..22.30 rows=1230 width=32) > > (18 rows) > > > > Why it no uses indexes at all? > > ------------------------------------------- > I'm no expert but I'd guess that the the planner doesn't know which > partition holds the latest time so it has to read them all. Agree. But why it not uses indexes when it reading them? -- engineer ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
