Horton

Re: How to share the result data of separated plan

Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi>

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From: Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Hitoshi Harada <umi.tanuki@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2010-11-08T22:38:15Z
Lists: pgsql-hackers 
On 2010-11-08 8:30 PM +0200, Tom Lane wrote:
> Marko Tiikkaja<marko.tiikkaja@cs.helsinki.fi>  writes:
>> On 2010-11-08 7:26 PM +0200, Tom Lane wrote:
>>> The alternative is to artificially serialize the DML CTEs, which
>>> while it does have some advantages doesn't seem like a win overall.
>
>> We've discussed this before and the consensus was that as long as we
>> don't change the results, we can optimize the materialization away.
>
> No, because the problem is mainly about what might happen if
> user-defined functions choose to look at the target tables.  We can't
> really tell what triggers are going to do, to take one item that the
> planner has no access to.

The relevant thread seems to be this one:

http://archives.postgresql.org/pgsql-hackers/2009-11/msg00003.php

and I do agree with what you said there.


Regards,
Marko Tiikkaja