On Mon, 05 Dec 2005 10:11:41 -0500, Tom Lane <[EMAIL PROTECTED]>
wrote:
>> Correlation -0.0736492
>> Correlation -0.237136
>That has considerable impact on the
>estimated cost of an indexscan
The cost estimator uses correlationsquared. So all correlations
between -0.3 and +0.3
> -Ursprüngliche Nachricht-
> Von: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Im Auftrag
> von Markus Wollny
> Gesendet: Montag, 5. Dezember 2005 16:41
> An: Tom Lane
> Cc: pgsql-performance@postgresql.org
> Betreff: Re: [PERFORM] Queries taking ages in P
> -Ursprüngliche Nachricht-
> Von: Tom Lane [mailto:[EMAIL PROTECTED]
> Gesendet: Montag, 5. Dezember 2005 16:12
> An: Markus Wollny
> Cc: pgsql-performance@postgresql.org
> Betreff: Re: AW: AW: [PERFORM] Queries taking ages in PG 8.1,
> have been much faster in
"Markus Wollny" <[EMAIL PROTECTED]> writes:
>> Could we see the pg_stats row for answer.session_id in both
>> 8.0 and 8.1?
> Here you are:
> 8.1:
> Correlation -0.0736492
> 8.0.3:
> Correlation -0.237136
Interesting --- if the 8.1 database is a dump and restore of the 8.0,
> -Ursprüngliche Nachricht-
> Von: Tom Lane [mailto:[EMAIL PROTECTED]
> Gesendet: Montag, 5. Dezember 2005 15:33
> An: Markus Wollny
> Cc: pgsql-performance@postgresql.org
> Betreff: Re: AW: [PERFORM] Queries taking ages in PG 8.1,
> have been much faster in PG&l
"Markus Wollny" <[EMAIL PROTECTED]> writes:
>> ... What I find interesting though is
>> that the plain index scan in 8.0 is so enormously cheaper
>> than it's estimated to be. Perhaps the answer table in your
>> 8.0 installation is almost perfectly ordered by session_id?
> Not quite - there ma
Hi!
> -Ursprüngliche Nachricht-
> Von: Tom Lane [mailto:[EMAIL PROTECTED]
> Gesendet: Sonntag, 4. Dezember 2005 19:32
> An: Markus Wollny
> Cc: pgsql-performance@postgresql.org
> Betreff: Re: [PERFORM] Queries taking ages in PG 8.1, have
> been much faster in PG
"Markus Wollny" <[EMAIL PROTECTED]> writes:
>> 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.
> Does this tell you anything useful? It's not on the same machine, mind
> you, but configuration for PostgreSQL is absolutely ide
Title: RE: [PERFORM] Queries taking ages in PG 8.1, have been much faster in PG<=8.0
Hi!
> -Ursprüngliche Nachricht-
> Von: Tom Lane [mailto:[EMAIL PROTECTED]]
> Gesendet: Donnerstag, 1. Dezember 2005 17:26
> An: Markus Wollny
> Cc: pgsql-performance@postgresql
"Markus Wollny" <[EMAIL PROTECTED]> writes:
>> 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.
> Please tell me what I can do to help in clearing up this issue, I'd be
> very happy to help!
The first thing to do is get 8.0
> -Ursprüngliche Nachricht-
> Von: Tom Lane [mailto:[EMAIL PROTECTED]
> Gesendet: Donnerstag, 1. Dezember 2005 17:26
> An: Markus Wollny
> Cc: pgsql-performance@postgresql.org
> Betreff: Re: [PERFORM] Queries taking ages in PG 8.1, have
> been much faster in PG<
"Markus Wollny" <[EMAIL PROTECTED]> 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. S
Hi!
I've got an urgent problem with an application which is evaluating a
monthly survey; it's running quite a lot of queries like this:
select SOURCE.NAME as TYPE,
count(PARTICIPANT.SESSION_ID) as TOTAL
from (
select PARTICIPANT.SESSION_ID
from survey.PARTICIPANT,
survey.ANSWE
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