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