On Wed, May 19, 2010 at 10:53 AM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Matthew Wakeling <matthew@xxxxxxxxxxx> writes: >> On Tue, 18 May 2010, Scott Marlowe wrote: >>> Aggregate (cost=902.41..902.42 rows=1 width=4) >>> -> Merge Join (cost=869.97..902.40 rows=1 width=4) >>> Merge Cond: (f.eid = ev.eid) >>> -> Index Scan using files_eid_idx on files f >>> (cost=0.00..157830.39 rows=3769434 width=8) > >> Okay, that's weird. How is the cost of the merge join only 902, when the >> cost of one of the branches 157830, when there is no LIMIT? > > It's apparently estimating (wrongly) that the merge join won't have to > scan very much of "files" before it can stop because it finds an eid > value larger than any eid in the other table. So the issue here is an > inexact stats value for the max eid. I changed stats target to 1000 for that field and still get the bad plan. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
