Date: Sat, 21 Aug 2021 14:19:50 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: ldh@laurent-hasson.com, pgsql-performance@postgresql.org
Subject: Re: Big Performance drop of Exceptions in UDFs between V11.2 and 13.4
Message-ID: <20210821191950.GW10479@telsasoft.com>
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On Sat, Aug 21, 2021 at 02:17:26PM -0400, Tom Lane wrote:
> "ldh@laurent-hasson.com" <ldh@laurent-hasson.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