Note that while the average hits/s between 100 and 500 is over 600 tps
for
Postgres there is a consistent smattering of plot points spread all the
way
down to 200 tps, well below the 400-500 tps that MySQL is getting.
Yes, these are due to checkpointing, mostly.
Also, note that a real forum would not insert 100 posts/s, so it would
not feel this effect. But in order to finish the benchmark in a correct
amount of time, we have to push on the inserts.
Some of those are undoubtedly caused by things like checkpoints and
vacuum
runs. Hopefully the improvements that are already in the pipeline will
reduce
them.
I am re-running it with other tuning, notably cost-based vacuum delay and
less frequent checkpoints, and it is a *lot* smoother.
These take a full night to run, so I'll post more results when I have
usefull stuff to show.
This has proven to be a very interesting trip to benchmarkland...
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TIP 6: explain analyze is your friend
