use PG_MODULE_MAGIC_EXT to report the full version

[tureba]

On PG 18+, PG_MODULE_MAGIC_EXT allows the module to report its name and version, where the version can be more fine-grained than the SQL-level extension.

So for an extension installed on a coarser version 1.6:

postgres=# select extname, extversion from pg_extension where extname = 'pg_cron';
extname | extversion
---------+------------
pg_cron | 1.6
(1 row)

This change allows the loaded modules to report, not only this...

postgres=# select pg_get_loaded_modules();
pg_get_loaded_modules

(,,pg_cron.so)
(1 row)

...but also the bugfix release:

postgres=# select pg_get_loaded_modules();
pg_get_loaded_modules

(pg_cron,1.6.7,pg_cron.so)
(1 row)

This change can help troubleshoot cases where the release is relevant and consulting the OS packages is more difficult, or where the .so might have changed without a database server restart.

It does add a small amount of extra work for releases, in the sense that pg_cron.c now has to be updated along with the changelog for every release henceforth.

[sandeep-edb]

LGTM

[Basha-EDB]

@tureba - As the Pull Request has been approved, could you please merge it at your earliest convenience.

[Basha-EDB]

@tureba - We would greatly appreciate it if you could prioritize merging your PR, Because we have a upcoming release sooner.

[ericmack]

approved

[marcoslot]

Would be nice to use a compile constant derived from the tag. We're likely to forget updating this.

[tureba]

I fully agree.

I see some other projects pulling their versions from macros of their own headers, or the Makefile providing the macro through CFLAGS, or other mechanisms.

But I didn't find a place where the pg_cron version was kept up to date, except in CHANGELOG.md. Not sure that parsing that is the best idea.

The file META.json looks interesting, but that also looks a bit outdated.

One could ask git-decorate for the latest tag, as you mention, but that wouldn't work when building from a .tar.gz, which some distributions may be doing.

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[tureba]

Now I pushed a new commit for the same branch that takes the version from the tip of CHANGELOG.md. I think this is an option. The other is to take the git tag, but I fear the git tag may not be available when distros build out of a .tar.gz.