From: Justin Pryzby <pryzby@telsasoft.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: ldh@laurent-hasson.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Big Performance drop of Exceptions in UDFs between V11.2 and 13.4
Date: Sat, 21 Aug 2021 14:19:50 -0500
Message-ID: <20210821191950.GW10479@telsasoft.com> (raw)
In-Reply-To: <2136207.1629569846@sss.pgh.pa.us>
References: <MN2PR15MB2560D77DFB58BD893E2EAAAD85C29@MN2PR15MB2560.namprd15.prod.outlook.com>
<MN2PR15MB2560AE2A878FBBE88DCFF33385C29@MN2PR15MB2560.namprd15.prod.outlook.com>
<2092859.1629558281@sss.pgh.pa.us>
<MN2PR15MB25607BDC72A325CA9B9D3E3385C29@MN2PR15MB2560.namprd15.prod.outlook.com>
<2136207.1629569846@sss.pgh.pa.us>
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
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To: pgsql-performance@postgresql.org
Cc: pryzby@telsasoft.com, tgl@sss.pgh.pa.us, ldh@laurent-hasson.com
Subject: Re: Big Performance drop of Exceptions in UDFs between V11.2 and 13.4
In-Reply-To: <20210821191950.GW10479@telsasoft.com>
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