On Tue, Feb 11, 2003 at 10:41:53 -0500, Tom Lane <[EMAIL PROTECTED]> wrote: > Greg Stark <[EMAIL PROTECTED]> writes: > > So one of the items on the TODO list is "Add hash for evaluating GROUP BY > > aggregates (Tom)" > > It's done in CVS tip ... give it a try. > > > The neat thing is that hash aggregates would allow grouping on data types that > > have = operators but no useful < operator. > > Hm. Right now I think that would barf on you, because the parser wants > to find the '<' operator to label the grouping column with, even if the > planner later decides not to use it. It'd take some redesign of the > query data structure (specifically SortClause/GroupClause) to avoid that.
I think another issue is that for some = operators you still might not be able to use a hash. I would expect the discussion for hash joins in http://developer.postgresql.org/docs/postgres/xoper-optimization.html would to hash aggregates as well. ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
