On Fri, Jun 17, 2011 at 7:48 AM, Kabu Taah <kabuutah@xxxxxx> wrote: > Load testing of postgresql 8.4 for OLTP application suitability showed that > throughput of the database significantly degraded over time from thousands > of write transactions per second to almost zero. Write transactions are in > given case insert/update/delete database transactions. The load driver used > for testing the database executed SQL queries in parallel threads and used > prepared statement and connection pooling. Postgres performance degraded in > a couple of minutes after the first run of the test, and the problem was > reproducible with only 2 parallel client threads. Subsequent test executions > showed degraded throughput since the beginning. The degradation has been > detected only in case of write transactions - select transactions were not > affected. After some time or after server restart the problem is > reproducible - test achieves high throughput and then degrades again. Linux > top does not show any postgres processes performing any significant work, > CPU usage during the test after degradation is <1%, io waits are also > normal. There are a ton of potential causes of this. The problem could be in your code, the database driver, etc. The first step is to try and isolate a query that is not running properly and to benchmark it with explain analyze. Being able to reproduce the problem in pgbench would explain a lot as well. merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
