Re: The job of a relational DBMS

From: Thomas Kellerer <OTPXDAJCSJVU_at_spammotel.com>
Date: Wed, 02 Dec 2009 09:55:55 +0100
Message-ID: <7nmociF3mpslkU1_at_mid.individual.net>

Gene Wirchenko, 02.12.2009 04:10:
>
> Granted that that would be implementation-dependent, but it would
> be convenient for it to do it that way while grouping. (How else
> would it?)

At least Oracle and Postgres do some kind of hashing most of the time, which does not sort the results at all.

> It would be silly for the DBMS to sort internally and
> then the converter do it again.

Agreed. But I think any modern optimizer will combine these steps if that would be quicker

Regards
Thomas Received on Wed Dec 02 2009 - 02:55:55 CST