(2014/08/12 18:34), Shigeru Hanada wrote:
Issues addressed by Eitoku-san were fixed properly, but he found a bug and a possible enhancement in the v2 patch.
Thank you for the review, Hanada-san and Eitoku-san!
* push-down check misses delete triggers update_is_pushdown_safe() seems to have a bug that it misses the existence of row-level delete trigger. DELETE statement executed against a foreign table which has row-level delete trigger is pushed down to remote, and consequently no row-level delete trigger is fired.
Ah, I noticed that the current code for that is not correct. Will fix.
* further optimization Is there any chance to consider further optimization by passing the operation type (UPDATE|DELETE) of undergoing statement to update_is_pushdown_safe()? It seems safe to push down UPDATE statement when the target foreign table has no update trigger even it has a delete trigger (of course the opposite combination would be also fine).
Good idea! Will improve that too.
* Documentation The requirement of pushing down UPDATE/DELETE statements would not be easy to understand for non-expert users, so it seems that there is a room to enhance documentation. An idea is to define which expression is safe to send to remote first (it might need to mention the difference of semantics), and refer the definition from the place describing the requirement of pushing-down for SELECT, UPDATE and DELETE.
Yeah, I also think that it would not necessarily easy for the users to understand which expression is safe to send. So I agree with that enhancement, but ISTM that it would be better to do that as a separate patch.
Thanks, Best regards, Etsuro Fujita -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
