RE: Big Performance drop of Exceptions in UDFs between V11.2 and 13.4

> -----Original Message-----
> From: Justin Pryzby <pryzby(at)telsasoft(dot)com>
> Sent: Saturday, August 21, 2021 15:20
> To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> Cc: ldh(at)laurent-hasson(dot)com; pgsql-performance(at)postgresql(dot)org
> Subject: Re: Big Performance drop of Exceptions in UDFs between V11.2
> and 13.4
>
> On Sat, Aug 21, 2021 at 02:17:26PM -0400, Tom Lane wrote:
> > "ldh(at)laurent-hasson(dot)com" <ldh(at)laurent-hasson(dot)com> writes:
> > > So you mean that on average, the 4x overhead of exceptions is
> around what you'd expect?
> >
> > Doesn't surprise me any, no. Exception recovery has to clean up after
> > a wide variety of possible errors, with only minimal assumptions about
> > what the system state had been. So it's expensive. More to the
> > point, the overhead's been broadly the same for quite some time.
> >
> > > As for results in general, yes, your numbers look pretty uniform
> across versions. On my end, comparing V11.2 vs V13.4 shows a much
> different picture!
> >
> > I'm baffled why that should be so. I do not think any of the
> > extensions you mention add any exception-recovery overhead,
> especially
> > not in sessions that haven't used them.
>
> Laurent, did you install binaries for v13.4 or compile it ?
>
> What about these ?
>
> SHOW shared_preload_libraries;
> SHOW session_preload_libraries;
> SHOW local_preload_libraries;
>
> Would you try to reproduce the issue with a fresh database:
> CREATE DATABASE udftest; ...
>
> Or a fresh instance created with initdb.
>
> As I recall, you're running postgres under a windows VM - I'm not sure if
> that's relevant.
>
> --
> Justin

Hello Justin,

- I used the standard installer from https://www.enterprisedb.com/downloads/postgres-postgresql-downloads for Windows X64 and upgraded from 13.3, which itself was pg_upgraded from 11.2.
- Yes, windows VM on VMWARE.
- No entries from shared_preload_libraries, session_preload_libraries or local_preload_libraries.
- Version is "PostgreSQL 13.4, compiled by Visual C++ build 1914, 64-bit".
- I created a new database and reran the scenarios without much of a change.
- I think I am going to install a whole fresh new instance from scratch and see if there may have been some weird stuff happening with the upgrade path I took?

Thank you,
Laurent Hasson.