Re: performance penalty between Postgresql 8.3.8 and 8.4.1 - Mailing list pgsql-performance

From Andres Freund
Subject Re: performance penalty between Postgresql 8.3.8 and 8.4.1
Date
Msg-id 200912081128.56076.andres@anarazel.de
Whole thread Raw
In response to Re: performance penalty between Postgresql 8.3.8 and 8.4.1  ("Schmitz, David" <david.schmitz@harman.com>)
List pgsql-performance
Hi David,

On Tuesday 08 December 2009 10:59:51 Schmitz, David wrote:
> >> With our data it is a performance difference from 1h16min
> >> (8.3.8) to 2h43min (8.4.1)
> On Postgresql 8.4.1
> Total runtime: 101.446 ms
> and on Postgresql  8.3.8:
> Total runtime: 29.366 ms
Hm. There obviously is more going on than these queries?

> Hash Join  (cost=2603.57..124518.03 rows=60772 width=61) (actual
time=62.359..97.268 rows=1444 loops=1)
> Nested Loop  (cost=21.00..3790.18 rows=81 width=61) (actual
time=0.210..26.098 rows=1444 loops=1)
Both misestimate the resultset quite a bit. It looks like happenstance that
the one on 8.3 turns out to be better...

Andres

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