Robert Haas wrote:
This has one MAJOR disadvantage: all the tuples from the CTE queries have to be buffered someplace, rather than streamed from the subquery up to the main query. For what may turn out to be pretty common uses cases like WITH tuples AS (DELETE FROM big_table_1 RETURNING ...) INSERT INTO big_table_2 ... this is going to suck pretty bad. I wonder if it isn't better to just use the same command-ID throughout and live with the weirdness of #2.
I haven't looked at the CTE code in much detail but I was under the impression that it had to store the results somewhere in any case. You're right, though, it sucks for this use case. Weirdness of #2 is probably a lot easier to live with.
I think you should definitely get some input from Tom Lane on this before you go too much further, but if he doesn't respond to this thread, I suggest trying again after CommitFest.
Agreed.
Does this have any impact on the pending DML-node patch?
Not really. This could be done without the patch, but we can use far more of the existing CTE code with the patch. Regards, Marko Tiikkaja -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
