>>>>> "Tom" == Tom Lane <t...@sss.pgh.pa.us> writes:
Tom> Hm. That's a hangover from when query_planner also gave back a Tom> Plan (singular) rather than a set of Paths. I don't see any Tom> fundamental reason why we couldn't generalize it to be a list of Tom> potentially useful output orderings rather than just one. But I'm Tom> a bit concerned about the ensuing growth in planning time; is it Tom> really all that useful? The planning time growth is a possible concern, yes. The potential gain is eliminating one sort step, in the case when the input has a usable sorted path but grouping_planner happens not to ask for it (when there's more than just a single rollup, the code currently asks for one of the sort orders pretty much arbitrarily since it has no real way to know otherwise). Whether that would justify it... I don't know. Maybe that's one to save for later to see if there's any feedback from actual use. -- Andrew (irc:RhodiumToad) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
