From: Alvaro Herrera <alvherre@commandprompt.com>
To: Lefteris <lsidir@gmail.com>
Cc: Jochen Erwied <jochen@pgsql-performance.erwied.eu>
Cc: pgsql-performance@postgresql.org
Subject: Re: Air-traffic benchmark
Date: Thu, 7 Jan 2010 11:14:23 -0300
Message-ID: <20100107141423.GC4315@alvh.no-ip.org> (raw)
In-Reply-To: <852badbc1001070610p698dc3cfr4628b1e7768990e6@mail.gmail.com>
References: <852badbc1001070438j36eb10d3qa22398ffcbef405f@mail.gmail.com>
<4B45E36E.4040706@tweakers.net>
<852badbc1001070547p48b47175vf87efc473e3bd41b@mail.gmail.com>
<26014999.20100107150535@erwied.eu>
<852badbc1001070610p698dc3cfr4628b1e7768990e6@mail.gmail.com>
Lefteris escribió:
> Yes, I am reading the plan wrong! I thought that each row from the
> plan reported the total time for the operation but it actually reports
> the starting and ending point.
>
> So we all agree that the problem is on the scans:)
>
> So the next question is why changing shared memory buffers will fix
> that? i only have one session with one connection, do I have like many
> reader workers or something?
No amount of tinkering is going to change the fact that a seqscan is the
fastest way to execute these queries. Even if you got it to be all in
memory, it would still be much slower than the other systems which, I
gather, are using columnar storage and thus are perfectly suited to this
problem (unlike Postgres). The talk about "compression ratios" caught
me by surprise until I realized it was columnar stuff. There's no way
you can get such high ratios on a regular, row-oriented storage.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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To: pgsql-performance@postgresql.org
Cc: alvherre@commandprompt.com, lsidir@gmail.com, jochen@pgsql-performance.erwied.eu
Subject: Re: Air-traffic benchmark
In-Reply-To: <20100107141423.GC4315@alvh.no-ip.org>
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