[tz] Version identification (was Re: Downstream use of 2021c)

[Tom Lane]

Philip Paeps via tz <tz at iana.org> writes:
> This is looking terribly fragmented.  Spare a thought for a hypothetical 
> engineer tasked with debugging a Java application on Debian with some 
> Python scripts on Fedora talking to a PostgreSQL database running on 
> FreeBSD...

BTW, that brings a thought to mind: why isn't there an easy way to
identify the release version of an installed tzdata tree?

I'm envisioning that there could be a text file at the top level,
say /usr/share/zoneinfo/version in typical layouts, containing
"2021a" or the appropriate string.  This'd make it a lot easier
to diagnose what you've got in a particular installation.

Some vendors (Red Hat at least) include the tzdata.zi file in
/usr/share/zoneinfo.  I persuaded Paul awhile back to put a
version comment at the top of that, so that provides a way to
determine the version if your vendor did that.  But it seems
like a mighty redundant approach.

			regards, tom lane