Re: [GENERAL] Need for help!

Thank you for your answer!
"You did not give CPU and disk info. But still 57 seems a small number.
What I guess is you're running pgbench with scale factor 1 (since you
haven't mentioned scale factor) and that causes extreme contention for
smaller tables with large number of clients."

My CPU is 2CPU: Intel(R) Xeon(TM) CPU 3.20GHz. Disk: disk system is RAID-5; OS CentOS. the number of scale in pgbench initialization is 100. It will be generate 10 000 000 rows in the accounts table. Fill factor is default.
In the other way, I heard that: PostgreSQL working with RAID-10 better than RAID-5 is it right?

       "Regarding maximum number of clients, check your "max_connections" setting."

I set max_connections is 200.

57 seems a small number, according to you, how much tps is normal or fast? and what is the different of "shared_buffers" and "effective_cache_size".

Thank you once more!
Regards,
Semi Noob

2008/5/15 Pavan Deolasee <pavan.deolasee@gmail.com>:

On Tue, May 13, 2008 at 2:43 PM, Semi Noob <seminoob@gmail.com> wrote:
>  But after upgrade the max clients is
> also 64 (?!?) Is this the maximum clients support by program pgbench (my
> server on Linux ver8.2.5, pgbench on Windows - version postgresql is 8.3.1)?
> And the number 57 tps is fast?
>

You did not give CPU and disk info. But still 57 seems a small number.
What I guess is you're running pgbench with scale factor 1 (since you
haven't mentioned scale factor) and that causes extreme contention for
smaller tables with large number of clients.

Regarding maximum number of clients, check your "max_connections" setting.

> Another questions, i heard that PostgreSQL does not support HT Technology,
> is it right?
>

I'm not sure what do you mean by HT, but if it's hyper threading, then
IMO that statement is not completely true. Postgres is not
multi-threaded, so a single process (or connection) may not be able to
use all the CPUs, but as long as there are multiple connections (each
connection corresponds to one backend process), as many CPUs will be
used.

> Last question, i don't understand so much the shmmax, shared_buffers, after
> upgrading my server from 4 GB RAM to 8 GB RAM, first i configure shmmax to
> 2GB, share_buffers to 1GB and start server, it runs, after that i set shmmax
> to 4GB and restart, it fails (?!?). The error logs said that not enough
> share memory!  and final i set shmmax to 3GB and share buffer to 2GB, it
> runs. Don't know why, can you explain?

That doesn't make sense. I am guessing that you are running a 32 bit
OS. 4GB of shmmax won't work on a 32 bit OS.

Thanks,
Pavan

Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com