Re: Performance problems testing with Spamassassin 3.1.0

Josh Berkus wrote:
> Matt,
>

> Well, it might be because we don't have a built-in GREATEST or LEAST prior to
> 8.1.   However, it's pretty darned easy to construct one.

I was more talking about min() and max() but yea, I think you knew where
I was going with it...

>
> Well, there's the general performance tuning stuff of course (postgresql.conf)
> which if you've not done any of it will pretty dramatically affect your
> througput rates.   And vacuum, analyze, indexes, etc.

I have gone though all that.

> You should also look at ways to make the SP simpler.  For example, you have a
> cycle that looks like:
>
> SELECT
>     IF NOT FOUND
>         INSERT
>     ELSE
>         UPDATE
>
> Which could be made shorter as:
>
> UPDATE
>     IF NOT FOUND
>         INSERT
>
> ... saving you one index scan.
>
> Also, I don't quite follow it, but the procedure seems to be doing at least
> two steps that the MySQL version isn't doing at all.  If the PG version is
> doing more things, of course it's going to take longer.
>
> Finally, when you have a proc you're happy with, I suggest having an expert
> re-write it in C, which should double the procedure performance.
>

Sounds like I need to completely understand what the proc is doing and
work on a rewrite.  I'll look into writing it in C, I need to do some
reading about how that works and exactly what it buys you.

Thanks for the helpful comments.

schu