Message-Id: <9304020916.AA25336@postgres.Berkeley.EDU>
From: aoki@postgres.berkeley.edu (Paul M. Aoki)
Subject: Re: big dumps from rewrites
To: postgres@postgres.berkeley.edu
Sender: pg_adm@postgres.berkeley.edu
In-Reply-To: Your message of Fri, 2 Apr 93 00:26:22 -0800 
	     <9304020826.AA25108@postgres.Berkeley.EDU> 
Date: Fri, 02 Apr 93 01:16:58 -0800
Sender: aoki@postgres.Berkeley.EDU

mcquaig!postgres@uunet.UU.NET (Postgres System User) writes:
> I certainly don't know if the problem I found is common.  However, I
> have discovered at least one way to cause the 70meg dumps discussed
> recently.  If rewrite rules fall into a circular logic, postgres will
> happily keep applying the same rules to themselves until it dies.

I have stack traces that go >300 calls deep before the process implodes.

The guy (male ;-) who wrote the code says it's documented somewhere 
that you aren't supposed to use circular rules (like the example
Carole provided to us, or your examples).  Which is probably as 
official an answer as you'll hear until someone decides to start 
throwing programmers at it ...

> It is actually quite spectacular to watch it get pregnant an explode.

This is a really, really disturbing analogy.  You would probably fit 
in well in our research group :-)

> Talk about robust. I had to watch, my poor 486 stopped everything else
> while was happening.  A little short on cpu cycles perhaps ;-}

That's ok.  It brings a DECstation5000 to its knees, too.  Not to 
mention a SparcStation2.  Soon, maybe a DECstation3000. ;-)

The spectre of infinite looping at 200MHz is truly frightening :-)

> If there is a more appropriate place to discuss this kind of techo-babble,
> please advise.  I don't wish to annoy the uninterested or look really 
> dumb when I'm wrong!

I don't think you've been wrong yet.  bug-postgres@postgres just goes
to a few postgres hackers, though.  post_questions@postgres has a slightly
wider distribution, but neither goes outside of UCB.

> Are the bug fixes at postgres.berkeley.edu ever
> made available anymore on an as found basis?

You'll have to ask the new management.
--
  Paul M. Aoki  |  CS Div., Dept. of EECS, UCB  |  aoki@postgres.Berkeley.EDU
                |  Berkeley, CA 94720           |  ...!uunet!ucbvax!aoki