>>>>> "Tom" == Tom Lane <t...@sss.pgh.pa.us> writes:
Tom> I've committed this after significant editorialization --- most Tom> notably, I pushed control of the sort step into the aggregate Tom> support functions. Initial tests suggest that your version is ~40% slower than ours on some workloads. On my system, this query takes ~950ms using our dev branch of the code, and ~1050ms on git master (using \timing in psql for timings, and taking the best of many consecutive runs): select count(*) from (select percentile_disc(0.5) within group (order by i) from generate_series(1,3) i, generate_series(1,100000) j group by j) s; About ~700ms of that is overhead, as tested by running this query with enable_hashagg=false: select count(*) from (select j from generate_series(1,3) i, generate_series(1,100000) j group by j) s; So your version is taking 350ms for the percentile calculations compared to 250ms for ours. -- 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