Christopher Kings-Lynne wrote:
> > Log message:
> > Finish implementation of hashed aggregation. Add enable_hashagg GUC
> > parameter to allow it to be forced off for comparison purposes.
> > Add ORDER BY clauses to a bunch of regression test queries that will
> > otherwise produce randomly-ordered output in the new regime.
>
> Out of interest (since I was away while this was proposed I assume),
> what's the idea with hashed aggergation? I assume each group is now in a
> hash bucket? How did it work before?
It sequential scanned the group of possible matches. How it hashes the
value and looks for matches that way --- much faster and the way most
db's do it.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
