From: Tom Lane <tgl@sss.pgh.pa.us>
To: Christophe Pettus <xof@thebuild.com>
cc: Adrian Klaver <adrian.klaver@aklaver.com>,
        "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
Subject: Re: UTC is not a time zone?
In-reply-to: <C430EBE1-EFA9-407D-8830-7C379B24B5AB@thebuild.com>
References: <327870A4-F35C-462C-9F64-E0838374AFDF@thebuild.com> <63e65356-9cb5-48b7-9bc5-5c734013ebe1@aklaver.com> <C430EBE1-EFA9-407D-8830-7C379B24B5AB@thebuild.com>
Comments: In-reply-to Christophe Pettus <xof@thebuild.com>
	message dated "Mon, 13 May 2024 10:50:26 -0700"
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Date: Mon, 13 May 2024 14:17:05 -0400
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Christophe Pettus <xof@thebuild.com> writes:
> On May 13, 2024, at 10:48, Adrian Klaver <adrian.klaver@aklaver.com> wro=
te:
>> https://www.postgresql.org/message-id/1273542.1712326418%40sss.pgh.pa.u=
s

> Thanks!  Similar, but I don't think it's that.  This was a sudden change=
 in a long-running connection that had issued a ton of ` SET TIMEZONE TO '=
UTC'; ` before the failure.

The underlying cause is likely roughly similar, to wit failure to read
/usr/share/zoneinfo/UTC (or the Postgres-private equivalent file).
The parent process would long since have cached the zone data in its
memory, but this error is in a parallel worker process, which'd have
to read the file for itself during startup.

What's causing that I can't say.  It doesn't look like we log the
errno anywhere when failing to read a zone file :-(

			regards, tom lane