From: ktm@rice.edu <ktm@rice.edu>
To: Böckler Andreas <andy@boeckler.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query-Planer from 6seconds TO DAYS
Date: Fri, 26 Oct 2012 10:30:49 -0500
Message-ID: <20121026153049.GC2872@aart.rice.edu> (raw)
In-Reply-To: <4818E807-E940-44F2-B10E-75038A82945C@boeckler.org>
References: <20121025182226.306900@gmx.com>
<A5F9B84E-0EEB-4D8F-A107-C4D5AB36A4EA@boeckler.org>
<20121026145513.GB2872@aart.rice.edu>
<4818E807-E940-44F2-B10E-75038A82945C@boeckler.org>
On Fri, Oct 26, 2012 at 05:15:05PM +0200, Böckler Andreas wrote:
> Hi Ken,
>
> Am 26.10.2012 um 16:55 schrieb ktm@rice.edu:
>
> > Hi Andy,
> >
> > You have the sequential_page_cost = 1 which is better than or equal to
> > the random_page_cost in all of your examples.
> > It sounds like you need
> > a sequential_page_cost of 5, 10, 20 or more.
>
> You're right it was sequential_page_cost = 1 because it's really irrelevant what I do here:
> set random_page_cost=2;
> set seq_page_cost=5;
> '2012-05-01' AND '2012-08-30' -> NESTEDLOOP
> '2012-04-01' AND '2012-08-30' -> SEQSCAN
>
> a) there will be a point, where things will go bad
> this is like patching up a roof 'till you find the next hole instead of making it right at the beginning of construction process
> b) they high seq costs might be true for that table (partition at 40gb), but not for the rest of the database
> Seqscan-Costs per table would be great.
>
> Regards,
>
> Andy
>
Hi Andy,
You can set them per tablespace. Maybe you could put the appropriate tables
that need the higher costing on the same one.
Regards,
Ken
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To: pgsql-performance@postgresql.org
Cc: ktm@rice.edu, andy@boeckler.org
Subject: Re: Query-Planer from 6seconds TO DAYS
In-Reply-To: <20121026153049.GC2872@aart.rice.edu>
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