Re: Preventing index scans for non-recoverable index AMs

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>
Cc: Jeff Davis <pgsql(at)j-davis(dot)com>, Kenneth Marshall <ktm(at)rice(dot)edu>, Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Preventing index scans for non-recoverable index AMs
Date: 2008-12-18 12:51:42
Message-ID: 494A475E.7010208@enterprisedb.com
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Pavan Deolasee wrote:
> BTW, if there is no proven case where hash index works significantly
> better than btree (that's what the doc says), why not just completely
> abandon it ?

That has been considered many times, see archives. I believe the changes
done in 8.4 actually made it faster for some cases. And as Kenneth
pointed out hash indexes can handle keys larger than 1/3 of page size,
that b-tree can't.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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