Re: How are foreign key constraints built? - Mailing list pgsql-general

From Jim C. Nasby
Subject Re: How are foreign key constraints built?
Date
Msg-id 20050125023058.GS67721@decibel.org
Whole thread Raw
In response to Re: How are foreign key constraints built?  (Greg Stark <gsstark@mit.edu>)
List pgsql-general
On Mon, Jan 24, 2005 at 09:24:49AM -0500, Greg Stark wrote:
> "Jim C. Nasby" <decibel@decibel.org> writes:
>
> > Well, every other database I've used can do index covering, which means
> > index scans *are* faster.
>
> Still not necessarily true. In a case like this it would still be random
> access which would be slower than sequential access.
Actually, even with random access, a covering index can still be faster.
Imagine a single-field index on a table with 40 fields.
--
Jim C. Nasby, Database Consultant               decibel@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828

Windows: "Where do you want to go today?"
Linux: "Where do you want to go tomorrow?"
FreeBSD: "Are you guys coming, or what?"

pgsql-general by date:

Previous
From: "Jim C. Nasby"
Date:
Subject: Re: Recursive queries
Next
From: "Florian G. Pflug"
Date:
Subject: Re: on update / on delete performance of foreign keys