Marko Tiikkaja <marko.tiikkaja@cs.helsinki.fi> writes:
> On 2011-02-25 1:36 AM, Tom Lane wrote:
>> Why is it necessary to hack the portal logic at all? The patch seems to
>> work for me without that. (I've fixed quite a few bugs though, so maybe
>> what this is really doing is masking a problem elsewhere.)
> Without hacking it broke when PQdescribePrepared was called on a
> prepared query like:
> WITH t AS (DELETE FROM foo)
> SELECT 1;
> Not sure if that's an actual problem, but it seemed like something worht
> fixing.
I can't replicate such a problem here --- do you have a concrete test
case? ISTM the issue would only have been a problem back when you
were trying to generate multiple PlannedStmts from a query like the
above. The current implementation with everything in one plantree
really ought to look just like a SELECT so far as the portal code
is concerned.
>> Also, why are we forbidding wCTEs in cursors? Given the current
>> definitions, that case seems to work fine too: the wCTEs will be
>> executed as soon as you fetch something from the cursor. Are you
>> just worried about not allowing a case that might be hard to support
>> later?
> Honestly, I have no idea. It might be a leftover from the previous
> design. If it looks like it's easy to support, then go for it.
Right now I'm thinking that it is best to continue to forbid it.
If we go over to the less-sequential implementation that I'm advocating
in another thread, the timing of the updates would become a lot less
predictable than I say above. If we refuse it for now, we can always
remove the restriction later, but the other way is more painful.
regards, tom lane