| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Greg Stark <gsstark(at)mit(dot)edu>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: We need index-only scans |
| Date: | 2010-11-12 14:54:18 |
| Message-ID: | 1289573523-sup-7227@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-hackers |
Excerpts from Heikki Linnakangas's message of vie nov 12 11:01:39 -0300 2010:
> It took me a while to understand what Greg meant as well. You can't scan
> a B-tree index in *physical order*, You have to first descend to the
> leftmost leaf, and follow the right pointers from there until you reach
> the rightmost leaf. That is a lot slower than seqscanning a file in
> physical order.
Oh, that makes more sense. I'm not sure that can be supported sanely
(i.e. not locking the whole index)
--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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