Re: Queries taking ages in PG 8.1, have been much faster in PG<=8.0 - Mailing list pgsql-performance

From Tom Lane
Subject Re: Queries taking ages in PG 8.1, have been much faster in PG<=8.0
Date
Msg-id 11568.1133454364@sss.pgh.pa.us
Whole thread Raw
In response to Queries taking ages in PG 8.1, have been much faster in PG<=8.0  ("Markus Wollny" <Markus.Wollny@computec.de>)
List pgsql-performance
"Markus Wollny" <Markus.Wollny@computec.de> writes:
> My current problem is that rewriting hundreds of queries, some of them
> quite a bit more complex than this one, but all of them using the same
> general scheme, would take quite a lot of time - and I'm expected to
> hand over the survey results ASAP. So I will obviously have to do a
> rewrite if there's just no other way, but I wondered if there might be
> some other option that would allow me to point the planner in the right
> direction so it would behave the same as in the previous versions,
> namely 8.0?

It looks like "set enable_nestloop = 0" might be a workable hack for
the immediate need.  Once you're not under deadline, I'd like to
investigate more closely to find out why 8.1 does worse than 8.0 here.

            regards, tom lane

pgsql-performance by date:

Previous
From: Michael Riess
Date:
Subject: Re: 15,000 tables
Next
From: "Markus Wollny"
Date:
Subject: Re: Queries taking ages in PG 8.1, have been much faster in PG<=8.0