Re: Reducing stats collection overhead

On 31-7-2007 5:07 Alvaro Herrera wrote:
> Arjen van der Meijden wrote:
>> Afaik Tom hadn't finished his patch when I was testing things, so I don't
>> know. But we're in the process of benchmarking a new system (dual quad-core
>> Xeon) and we'll have a look at how it performs in the postgres 8.2dev we
>> used before, the stable 8.2.4 and a fresh HEAD-checkout (which we'll call
>> 8.3dev). I'll let you guys (or at least Tom) know how they compare in our
>> benchmark.
>
> So, ahem, did it work? :-)

The machine turned out to have a faulty mainboard, so we had to
concentrate on first figuring out why it was unstable and then whether
the replacement mainboard did make it stable in a long durability
test.... Of course that behaviour only appeared with mysql and not with
postgresql, so we had to run our mysql-version of the benchmark a few
hundred times, rather than testing various versions, untill the machine
had to go in production.

So we haven't tested postgresql 8.3dev on that machine, sorry.

Best regards,

Arjen

>
>
>> On 18-5-2007 15:12 Alvaro Herrera wrote:
>>> Tom Lane wrote:
>>>> Arjen van der Meijden told me that according to the tweakers.net
>>>> benchmark, HEAD is noticeably slower than 8.2.4, and I soon confirmed
>>>> here that for small SELECT queries issued as separate transactions,
>>>> there's a significant difference. I think much of the difference stems
>>>> from the fact that we now have stats_row_level ON by default, and so
>>>> every transaction sends a stats message that wasn't there by default
>>>> in 8.2. When you're doing a few thousand transactions per second
>>>> (not hard for small read-only queries) that adds up.
>>> So, did this patch make the performance problem go away?
>
>