[tz] Getting current tzdb version in use

[Tom Lane]

Paul Eggert <eggert at cs.ucla.edu> writes:
> Robert Elz wrote:
>> Which we don't in NetBSD, that file adds no value for us.

> The main intent of the tzdata.zi file was to have a single file containing all 
> the information of all the TZif files, so that a software upgrade procedure 
> could get a copy of tzdata.zi and then run zic to generate the other files. 
> tzdata.zi is considerably smaller than a tarball of the TZif files it 
> represents: a factor of 4 smaller if you use gzip to compress both, and a factor 
> of 3 smaller even if you use lzip which is much better at compressing.

FWIW, Postgres has already switched over from shipping the raw tzdb text
files in our tarball to shipping tzdata.zi, precisely because it's a lot
smaller and you get the same output after running it through zic.
So it adds value for us, whether or not any particular other platform
wants to use it.  And we like having some readable version indication
in it, too.

I think the request to propagate that version info into the file tree
installed by zic is equally reasonable.  As noted, a lot of people have
invented their own solutions for this omission, which proves that
there's a need for it.

			regards, tom lane