On Wed, May 19, 2010 at 2:27 PM, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: > 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. And of course ran analyze across the table... -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
