I've come up with a patch designed to improve performance for the case
where Postgres has one or more overflowed subtransactions, i.e. at
least one open transaction has >64 subtransactions.
So far, performance results are very promising, which shows a loss of
performance of x8-9 unpatched and almost fully restored performance in
the patched version, for a test case of overflowed subxacts with data
contention, in the presence of a long running transaction.
[Image attached]
To be accepted into PG16, we think it's a good idea to gather wide
performance results.
If you use subtransactions in your application, could you help
characterize the performance of this patch? Sorry, no binaries
available, just the patch.
https://www.postgresql.org/message-id/attachment/140021/002_minimize_calls_to_SubTransSetParent.v12.patch
Any test case is OK, as long as you publish the code to run it and
publish the measurements with/without the patch.
Thanks very much.
--
Simon Riggs http://www.EnterpriseDB.com/
