Re: Almost infinite query -> Different Query Plan when changing where clause value

From: Kevin Grittner
Subject: Re: Almost infinite query -> Different Query Plan when changing where clause value
Date: ,
Msg-id: 4B7519C5020000250002F242@gw.wicourts.gov
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In response to: Almost infinite query -> Different Query Plan when changing where clause value  (lionel duboeuf)
Responses: Re: Almost infinite query -> Different Query Plan when changing where clause value  (lionel duboeuf)
List: pgsql-performance


lionel duboeuf <> wrote:

> Some informations:
> The following problem has been detected on
>    Postgresql 8.3 and 8.4. on System linux or windows
>    Default AutoVacuum daemon working
>    One pg_dump every day
> This happens sometimes and i don't see what can be the cause.
> A manual Vacuum Analyse repair that problem.

It's good to know that the issue has been observed in more than one
release or on more than one platform, but it's also useful to get a
bit more information about one particular occurrence.  Please read
this:

http://wiki.postgresql.org/wiki/SlowQueryQuestions

In particular, knowing such things as your postgresql.conf settings,
the disk configuration, how much RAM the machine has, etc. can allow
us to provide more useful advice.

Please run these as EXPLAIN ANALYZE (or at least whatever you can
get to finish that way) instead of just EXPLAIN.  If you can let the
slow one run through EXPLAIN ANALYZE overnight or on a test machine
so that it can complete, it will give us a lot more with which to
work.  Please attach wide output (like that from EXPLAIN) as a text
attachment, to prevent wrapping which makes it hard to read.

-Kevin


pgsql-performance by date:

From: "Kevin Grittner"
Date:
Subject: Re: Almost infinite query -> Different Query Plan when changing where clause value
From: Greg Smith
Date:
Subject: Re: moving pg_xlog -- yeah, it's worth it!