Re: Writeable CTEs and empty relations

Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi> writes:
> On 2010-02-10 02:19 +0200, Tom Lane wrote:
>> You still haven't explained why it's a good idea to change the snapshot
>> after the executor has started.  Right at the moment I'm prepared to
>> reject the patch on that ground alone.

> The patch only touches the snapshot's curcid.  That's needed to allow
> the queries see the tuples of the DML WITHs ran before that particular
> query.

... and they will also see, for example, tuples inserted by triggers
fired by those queries.  I thought the plan for this feature was to
store and re-read the RETURNING data, not to go back and re-read the
underlying tables.
        regards, tom lane