On 2015/10/17 9:58, Robert Haas wrote:
But with Etsuro Fujita's patch, and I think what you have proposed has been similar, how are you going to do it? The proposal is to call the recheck method and hope for the best, but what is the recheck method going to do? Where is it going to get the previously-returned tuple?
As I explained in a previous email, just returning the previously-returned tuple is not good enough.
How will it know if it has already returned it during the lifetime of this EPQ check? Offhand, it looks to me like, at least in some circumstances, you're probably going to return whatever tuple you returned most recently (which has a good chance of being the right one, but not necessarily) over and over again. That's not going to fly.
No. Since the local join execution plan is created so that the scan slot for each foreign table involved in the pushed-down join looks at its EPQ slot, I think the plan can return at most one tuple.
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
