From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
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To: | Greg Stark <gsstark(at)mit(dot)edu> |
Cc: | Gokulakannan Somasundaram <gokul007(at)gmail(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers list <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: A thought on Index Organized Tables |
Date: | 2010-02-22 14:38:34 |
Message-ID: | 20100222143834.GB4629@alvh.no-ip.org |
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Lists: | pgsql-hackers |
Greg Stark escribió:
> On Mon, Feb 22, 2010 at 8:18 AM, Gokulakannan Somasundaram
> <gokul007(at)gmail(dot)com> wrote:
> > a) IOT has both table and index in one structure. So no duplication of data
> > b) With visibility maps, we have three structures a) Table b) Index c)
> > Visibility map. So the disk footprint of the same data will be higher in
> > postgres ( 2x + size of the visibility map).
>
> These sound like the same point to me. I don't think we're concerned
> with footprint -- only with how much of that footprint actually needs
> to be scanned. So if we have a solution allowing the scan to only need
> to look at the index then the extra footprint of the table doesn't
> cost anything at run-time. And the visibility map is very small.
Moreover, the visibility map is already there.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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