Hello Greg,
If you add this to
https://commitfest.postgresql.org/action/commitfest_view?id=18 I'll review it
next month.
Ok. Thanks. I just did that.
I have a lot of use cases for a pgbench that doesn't just run at 100%
all the time. I had tried to simulate something with simple sleep
calls, but I realized it was going to take a stronger math basis to do
the job well.
The situations where I expect this to be useful all require collecting
latency data and then both plotting it and doing some statistical analysis.
pgbench-tools computes worst-case and 90th percentile latency for example,
along with the graph over time. There's a useful concept that some of the
official TPC tests have: how high can you get the throughput while still
keeping the latency within certain parameters. Right now we have no way to
simulate that. What we see with write-heavy pgbench is that latency goes
crazy (>60 second commits sometimes) if all you do is hit the server with
maximum throughput. That's interesting, but it's not necessarily relevant in
many cases.
Indeed. It is a good thing that my proposed feature can help in more
situations than my particular need.
--
Fabien.
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