Douglas Doole <dougdo...@gmail.com> writes: > Would we be better off moving those cases into the while loop I added to > avoid the recursion?
No. You can't easily avoid recursion for the merge-append case, since that has to descend to multiple children. TBH I dislike the fact that you did the subquery case randomly differently from the existing cases; it should just have been added as an additional recursive case. Since this is done only once at query startup, worrying about hypothetical micro-performance issues seems rather misguided. Perhaps, since this function is recursive, it ought to have a check_stack_depth call, just to be safe. I'm dubious though that it could ever eat more stack than the preceding node-initialization calls, so maybe we needn't bother. In the long run I wonder whether we should convert "push down bound" into a generic node operation like the others managed by execAmi.c. It seems like you could push a limit through any node type that's guaranteed not to reduce the number of rows returned, and so we're missing cases. Maybe they're not ones that are important in practice, but I'm unsure. > The two casts I added (to SubqueryScanState and Node) should probably be > changed to castNode() calls. The SubqueryScanState cast seems fine given that it immediately follows an IsA() check. You can't use castNode() for a cast to Node, because that's a generic not a specific node type. regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers