From: Richard Huxton <dev@archonet.com>
To: Andreas Haumer <andreas@xss.co.at>
Cc: Guillaume Cottenceau <gc@mnc.ch>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query performance problems with partitioned tables
Date: Mon, 30 Apr 2007 14:45:05 +0100
Message-ID: <4635F2E1.3090602@archonet.com> (raw)
In-Reply-To: <4635EF3A.1070204@xss.co.at>
References: <4635D678.3050205@xss.co.at>
<87ps5mgghp.fsf@meuh.mnc.lan>
<4635EF3A.1070204@xss.co.at>
Andreas Haumer wrote:
>
> I think the planner could do the following:
>
> a) It could make a better decision in which direction to scan
> the partitions (depending on sort order involved in the query)
>
> b) It could stop scanning as soon as there can not be any further
> resulting row according to the CHECK constraints given on the tables.
[snip]
> Perhaps the logic to implement this is complex, but IMHO
> it _should_ be doable (and proofable), shouldn't it?
Ah, it might be do-able for some subset of cases, but is it
cost-effective to check for in *all* cases? Don't forget the constraints
and where clauses can be arbitrarily complex.
--
Richard Huxton
Archonet Ltd
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: dev@archonet.com, andreas@xss.co.at, gc@mnc.ch
Subject: Re: Query performance problems with partitioned tables
In-Reply-To: <4635F2E1.3090602@archonet.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox