On Fri, Jan 14, 2022 at 1:17 PM Julien Rouhaud <rjuju123@gmail.com> wrote:
On Thu, Jan 13, 2022 at 10:27:31PM +0000, Bossart, Nathan wrote: > Thanks for the new patch! > > + <para> > + Returns a record of information about the backend's subtransactions. > + The fields returned are <parameter>subxact_count</parameter> identifies > + number of active subtransaction and <parameter>subxact_overflow > + </parameter> shows whether the backend's subtransaction cache is > + overflowed or not. > + </para></entry> > + </para></entry> > > nitpick: There is an extra "</para></entry>" here.
Also the sentence looks a bit weird. I think something like that would be better:
> + Returns a record of information about the backend's subtransactions. > + The fields returned are <parameter>subxact_count</parameter>, which > + identifies the number of active subtransaction and <parameter>subxact_overflow > + </parameter>, which shows whether the backend's subtransaction cache is > + overflowed or not.
Thanks for looking into this, I will work on this next week.
While on the sub-transaction overflow topic, I'm wondering if we should also raise a warning (maybe optionally) immediately when a backend overflows (so in GetNewTransactionId()).
Like many I previously had to investigate a slowdown due to sub-transaction overflow, and even with the information available in a monitoring view (I had to rely on a quick hackish extension as I couldn't patch postgres) it's not terribly fun to do this way. On top of that log analyzers like pgBadger could help to highlight such a problem.
I don't want to derail this thread so let me know if I should start a distinct discussion for that.