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Re: [PATCHES] WITH RECURSIVE updated to CVS TIP

From: David Fetter <david(at)fetter(dot)org>
To: Tatsuo Ishii <ishii(at)postgresql(dot)org>
Cc: y-asaba(at)sraoss(dot)co(dot)jp, postgres(at)cybertec(dot)at,pgsql-patches(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCHES] WITH RECURSIVE updated to CVS TIP
Date: 2008-07-16 05:22:57
Message-ID: 20080716052256.GQ5623@fetter.org (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
On Wed, Jul 16, 2008 at 01:57:04PM +0900, Tatsuo Ishii wrote:
> > > No idea.  What do you think if we allow only one query name at the
> > > moment.
> > 
> > I'm not sure I understand what that has to do with sorting.
> > 
> > Please find attached a place where I've found some problems sorting by
> > tree by array as Asaba-san suggested.
> 
> Humm. your problem seems to do nothing with the problem I refer to.

Sorry about that.  Is my problem reproducible?  Is there maybe some
way to include regression tests around it?

> What I have in my mind is something like:
> 
> WITH RECURSIVE foo(a, b) AS
> (SELECT ... UNION SELECT...),
> 
> bar(c, d) AS
> (SELECT ... FROM foo WHERE ...UNION...)
> )
> SELECT * FROM foo;
> 
> In this there are two query names (foo, bar) and we need to detect the
> dependency that bar relies on foo before processing the query.

I think mutually recursive queries may have been dropped from
SQL:2008.

> However, as I said earlier, this kind of use case would be rare in
> the real world, and I'd like to limit ourselves to having only one
> query name at the moment.
> 
> Also I suggest to concentrate on reviewing the WITH RECURSIVE
> implementation itself now, rather than discussing how to use git
> repository or how to write an interesting WITH RECURSIVE
> applications.
> 
> Don't get me wrong. I believe git is a great tool. But we have
> limited time and need to think about the priority.

Fair enough :)

Cheers,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david(dot)fetter(at)gmail(dot)com

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