From: Luke Lonergan <llonergan@greenplum.com>
To: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Simon Riggs <simon@2ndquadrant.com>
To: Kurt Harriman <kharriman@greenplum.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Sort performance on large tables
Date: Tue, 08 Nov 2005 11:09:07 -0800
Message-ID: <BF9637D3.1338F%llonergan@greenplum.com> (raw)
In-Reply-To: <20051108093500.N31541@megazone.bigpanda.com>
Stephan,
On 11/8/05 9:38 AM, "Stephan Szabo" <sszabo@megazone.bigpanda.com> wrote:
>> >
>> > Just as we find with a similar comparison (with a "popular commercial,
>> > proprietary database" :-) Though some might suggest you increase
>> > work_mem or other tuning suggestions to speed sorting, none work. In
>> > fact, we find that increasing work_mem actually slows sorting slightly.
>
> I wish you'd qualify your statements, because I can demonstrably show that
> I can make sorts go faster on my machine at least by increasing work_mem
> under some conditions.
>
Cool can you provide your test case please? I¹ll ask our folks to do the
same, but as I recall we did some pretty thorough testing and found that it
doesn¹t help. Moreover, the conclusion was that the current algorithm isn¹t
designed to use memory effectively.
Recognize also that we¹re looking for a factor of 10 or more improvement
here this is not a small increase that¹s needed.
- Luke
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, sszabo@megazone.bigpanda.com, simon@2ndquadrant.com, kharriman@greenplum.com
Subject: Re: Sort performance on large tables
In-Reply-To: <BF9637D3.1338F%llonergan@greenplum.com>
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