Re: Bags versus sets; are they needed?

From: <paul.vernon_at_ukk.ibmm.comm>
Date: Tue, 2 Apr 2002 15:30:43 +0100
Message-ID: <a8cg4b$17mc$1@sp15at20.hursley.ibm.com>

> I believe that the original motivation for returning bags ("sets" with
> duplicate values retained) was one of performance: to eliminate the
> extra step, that would be required if duplicates were to be removed.
> My question is simple: Do you personally have code, where the
> retaining of duplicate tuples is essential/convenient/whatever? If so
> - could you provide me with an insight in to what problem is solved.

Have a look at C J Date on this subject.

Double Trouble, DOuble Trouble Part1
http://www.dbdebunk.com/cjddtdt.htm

For what it is worth. I agree with him: There are no problems that need to use "bags" to be solved.

Also, I'm no mathematician but his suggestion that "bags" can't exist even in principle is persuasive to me.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Tue Apr 02 2002 - 08:30:43 CST