Re: Need for help!

Justin <justin@xxxxxxxxxxxxxxx> · Thu, 15 May 2008 10:45:36 -0400

Pavan Deolasee wrote:

  On Thu, May 15, 2008 at 3:48 PM, Semi Noob <seminoob@xxxxxxxxx> wrote:

    I set max_connections is 200.

What error message you get when you try with more than 64 clients ?

I have the max connection  set 50.  You want to be careful with this
setting if  theres allot of active users and the processes/users get
hung open this will be eating up memory on the server This number needs
to be set to the maximum number of users  you ever want on the server
at any one time.  If you get to many hung open presses performance gets
hurt. 

    57 seems a small number, according to you, how much tps is normal or fast?

Its difficult to say how much is good. On my laptop for s = 10, c =
40, t = 1000, I get 51 tps. But on a larger 2 CPU, 2 GB, 3 RAID 0
disks for data and a separate disk for xlog, I get  232 tps.

As Pevan has started TPS number is directly related to how fast your
hardware is.   51 tps is not very good given the hardware specs you
have stated. 

Now the server i have gets 1500 to 2000 tps depending on the the test
.  We had a pretty detail discussion about performance numbers back in
March 

http://archives.postgresql.org/pgsql-performance/2008-03/thrd3.php#00370

the thread is called Benchmark: Dell/Perc 6, 8 disk RAID 10. 

RIAD 5 is a terrible setup for performance RAID 10 seems to be what
everybody goes with unless you get in SANs storage or other more
complicated setups

    and what is the different of "shared_buffers" and "effective_cache_size".

"shared_buffers" is the size of the buffer pool which Postgres uses to
cache the data blocks.
"effective_cache_size" is usually size of the shared buffer plus
estimate of whatever data OS can cache. Planner uses this
approximation to choose right plan for execution.

http://www.postgresql.org/docs/8.3/interactive/runtime-config-query.html

Thanks,
Pavan