Re: What constitutes "reproducible" numbers from pgbench?

On Tuesday, April 21, 2015 7:43 PM, Andy Colson wrote:
> On 4/21/2015 9:21 AM, Holger(dot)Friedrich-Fa-Trivadis(at)it(dot)nrw(dot)de wrote:
>> Exactly what constitutes "reproducible" values from pgbench? I keep
>> getting a range between 340 tps and 440 tps or something like that
> I think its common to get different timings. I think its ok because things are changing (files, caches, indexes, etc).

As I found out, our test server is a virtual machine, so while I should be "alone" on that virtual machine, of course I have no idea what else might be going on on the physical server the virtual machine is running on. That would explain the somewhat wide variations.

Qingqing Zhou wrote that the range between 340 tps and 440 tps I keep getting is not ok and numbers should be the same within several per cent. Of course, if other things are going on on the physical server, I can't always expect a close match.

Since someone asked, the point of the exercise is to see if and how various configurations in postgresql.conf are affecting performance.

Cheers,
Holger Friedrich