Hi,
Right now when you run pgbench, the results vary considerably from run to run even if you completely rebuild the database every time. I've found that a lot of that variation comes from two things:
The main purpose of pgbench runs is an "apples to apples" comparison of 2 source bases. One pristine Postgresql source base and another base being the same source patched with supposed enhancements. As long as we use the same postgresql.conf, same hardware environment and exactly same parameter pgbench runs, the difference in the TPS values observed between the 2 sources should be a good enough indicator as to the viability of the new code, dont you think? E.g. autovacuum will trigger on certain tables only if the threshold is over the limit. So that gets tied in to the update rate. The "shared_buffers" will become a bottleneck only if the code and the run is I/O intensive enough etc. IMHO, as long as the same environment holds true for both the source base runs, we should not see unexplained variations as per the reasons you have mentioned in the observed TPS values. Regards, Nikhils -- EnterpriseDB http://www.enterprisedb.com
