On Fri, 2008-12-26 at 14:17 -0500, Tom Lane wrote: > Greg Stark <greg.st...@enterprisedb.com> writes: > > Yeah, it seems like adding a flag like iswindowable to aggregate > > functions is the safest option. >
> So the alternatives I see are: > > 1. Go back to Hitoshi's plan of passing WindowAggState to the > aggregates. This will require changing every one of the ten aggregates > in the core distro, as well as every third-party aggregate that has > a similar optimization; and we just have to keep our fingers crossed > that anyone who's taking a short-cut will fix their code before it > fails in the field. > > 2. Use an intermediate dummy AggState as I have in my version, but > document some convention for telling this from a "real" AggState > when needed. (Not hard, we just pick some field that would never be > zero in a real AggState and document testing that.) This is certainly > on the ugly side, but it would very substantially cut the number of > places that need changes. Only aggregates that are doing something > irreversible in their final-functions would need to be touched. > > If we were working in a green field then #1 would clearly be the > preferable choice, but worrying about compatibility with existing > third-party aggregates is making me lean to #2. Comments? > > regards, tom lane > I believe the goal should be correctness but why not both? Fix what we can and put in place a "work around" that would be removed in 8.5? Joshua D. Drake -- PostgreSQL Consulting, Development, Support, Training 503-667-4564 - http://www.commandprompt.com/ The PostgreSQL Company, serving since 1997 -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
