Tom Lane <[EMAIL PROTECTED]> writes:
> Greg Stark <[EMAIL PROTECTED]> writes:
> > Last I heard the reason count(*) was so expensive was because its state
> > variable was a bigint. That means it doesn't fit in a Datum and has to be
> > alloced and stored as a pointer. And because of the Aggregate API that means
> > it has to be allocated and freed for every tuple processed.
>
> There's a hack in 8.1 to avoid the palloc overhead (courtesy of Neil
> Conway IIRC).
ah, cool, missed that.
--
greg
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
