On Wed, 16 Jun 2010, Balkrishna Sharma wrote:
Hello,I will have a web application having postgres 8.4+ as backend. At
any given time, there will be max of 1000 parallel web-users interacting
with the database (read/write)I wish to do performance testing of 1000
simultaneous read/write to the database.
When you set up a server that has high throughput requirements, the last
thing you want to do is use it in a manner that cripples its throughput.
Don't try and have 1000 parallel Postgres backends - it will process those
queries slower than the optimal setup. You should aim to have
approximately ((2 * cpu core count) + effective spindle count) number of
backends, as that is the point at which throughput is the greatest. You
can use pgbouncer to achieve this.
I can do a simple unix script on the postgres server and have parallel
updates fired for example with an ampersand at the end. Example:
echo '\timing \\update "DAPP".emp_data set f1 = 123where emp_id =0;' |
"psql" test1 postgres|grep "Time:"|cut -d' ' -f2- >>
"/home/user/Documents/temp/logs/$NUM.txt" &pid1=$! echo '\timing
\\update "DAPP".emp_data set f1 = 123 where emp_id =2;' | "psql" test1
postgres|grep "Time:"|cut -d' ' -f2- >>
"/home/user/Documents/temp/logs/$NUM.txt" &pid2=$! echo '\timing
\\update "DAPP".emp_data set f1 = 123 where emp_id =4;' | "psql" test1
postgres|grep "Time:"|cut -d' ' -f2- >>
"/home/user/Documents/temp/logs/$NUM.txt" &pid3=$! .............
Don't do that. The overhead of starting up an echo, a psql, and a grep
will limit the rate at which these queries can be fired at Postgres, and
consume quite a lot of CPU. Use a proper benchmarking tool, possibly on a
different server.
Also, you should be using a different username to "postgres" - that one is
kind of reserved for superuser operations.
Matthew
--
People who love sausages, respect the law, and work with IT standards
shouldn't watch any of them being made. -- Peter Gutmann
--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
