Re: upper planner path-ification

>>>>> "Tom" == Tom Lane <tgl@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)