Re: Subtransactions + a long-running transaction leading to performance degradation on standbys

> 20 авг. 2021 г., в 09:45, Nikolay Samokhvalov <nik(at)postgres(dot)ai> написал(а):
>
> The patches changing the SLRU algorithm and adding GUCs to control the buffer sizes look really promising. Optimization in this area would really help those who use SAVEPOINTs. I suspect, we have a lot of such users – ORMs like Rails and Hibernate tend to use them for fancy nesting transaction processing.

Awesome analysis, Nik, thanks!
Yes, I think there are many workloads that would benefit a lot from bigger SLRU caches.

I just want to note, that on your screenshot unpatched version runs 400K tps, while patched runs 280K tps. I see the dates are different and this effect is not observed in [0]. Probably, you run tests on different machines.

While your experiments clearly shows that patch can save DB from degradation under pathological workload it would be great to ensure patch does not incur penalty on normal workload.

Thank you!

Best regards, Andrey Borodin.

[0] https://gitlab.com/postgres-ai/postgresql-consulting/tests-and-benchmarks/-/issues/20