Re: PostgreSQL scalability on Sun UltraSparc T1

On 29-7-2006 19:01, Joshua D. Drake wrote:
> Well I would be curious about the postgresql.conf and how much ram
> etc... it had.

It was the 8core version with 16GB memory... but actually that's just
overkill, the active portions of the database easily fits in 8GB and a
test on another machine with just 2GB didn't even show that much
improvements when going to 7GB (6x1G, 2x 512M), it was mostly in the
range of 10% improvement or less.

Anyway, the differences to the default postgresql.conf:
shared_buffers = 30000
Tests with 40k, 50k en 60k didn't really show improvements.

work_mem = 2048
This probably could've been set higher with the sheer amount of
not-really-used memory.

maintenance_work_mem = 65535
Not really important of course

max_fsm_pages = 50000
Somehow it needed to be set quite high, probably because we only cleaned
up after doing over 200k requests.

effective_cache_size = 350000
As said, the database fitted in 8GB of memory, so I didn't see a need to
set this higher than for the 8GB machines (x4200 and another T2000 we had).

default_statistics_target = 200
For a few columns on the largest tables I manually raised it to 1000

log_min_duration_statement = 1000
I'm not sure if this has much overhead? Stats logging was turned/left on
as well.
Turning that off improved it a few percent.

> I understand, I just have a feeling that we could do even better :) I do
> appreciate all your efforts.

Well, I'll keep that in mind :)
What it makes even worse for MySQL is that it had (on another machine)
about 8M hits on the query cache for 4M inserts, i.e. half of the
queries weren't even executed on it.

Best regards,

Arjen