Re: 8.3RC2 vs 8.2.6 testing results

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Vlad <marchenko(at)gmail(dot)com> writes:
> 2. We ran several tests and found 8.3 generally 10% slower than 8.2.6.

The particular case you are showing here seems to be all about the speed
of hash aggregation --- at least the time differential is mostly in the
HashAggregate step.  What is the data type of a_id?  I speculate that
you're noticing the slightly slower/more complicated hash function that
8.3 uses for integers.  On a case where the data was well distributed
you'd not see any countervailing efficiency gain from those extra
cycles.

			regards, tom lane