Hitoshi Harada <umi.tan...@gmail.com> writes: > 2010/1/19 Tom Lane <t...@sss.pgh.pa.us>: >> AFAICS that doesn't mean it can't be the >> canonicalized form of the sort key. If a column is dropped out of the >> canonical sort key then it's simply redundant, and hence not relevant to >> determining the range.
> Yeah, that's my point, too. The planner has to distinguish "four" from > sort pathkeys and to teach the executor the simple information which > column should be used to determine frame. I was bit wrong because some > of current executor code isn't like it, like using ordNumCols == 0 to > know whether partition equals to frame, though.... BTW, watch out for the possibility that the canonicalized key is empty. This isn't an error case --- what it means is that the planner has proven that all the rows have equal sort key values, so there's no need to compare anything. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers