Why does everyone run ancient Postgres versions?

Because the actual process of upgrading Postgres is terrible.

I say this as someone who absolutely loves using it, but the actual process of upgrading Postgres is something that takes significant downtime, is error-prone and you're often better off just dumping all the databases and reimporting them in a new folder. (A good idea in general since it'll vacuum and compact indexes as well if you do it, combining a few maintenance routines in your upgrade path.)

It requires having the previous version of Postgres installed, something which can mess with a number of distro policies (not to mention docker, which is the most popular way to deploy software that will typically rely on Postgres), and unlike most software with that issue, Postgres is software you want to be managed by your distro.

Therefore, most people only upgrade by necessity - when their distro forces the upgrade or the version they're using reaches EOL.

> Postgres is software you want to be managed by your distro.

Why?

For production systems I generally try to avoid using anything not built internally. When it comes to PostgreSQL, for example, if you want to submit benchmarks, or you want to report bugs, an important or sometimes a mandatory component is to provide compilation flags. Also, seeing how every kind of storage can act in a different way, tuning of higher-level storage programs seems inevitable. Even though PostgreSQL has a lot of configurations that can be done to the compiled program, some (eg. block size) are compile-time that can only be changed by compiling the program.

Depends on your scale. If you're a startup or even just a small side service, performance isn't going to be a bottleneck and you/the org wants the thing to be fire and forget, including bug fixes and especially security patches. A distro takes care of all of those generally and makes sure the dependencies have the same care taken.

> A distro takes care of all of those generally and makes sure the dependencies have the same care taken.

So does using the vendor repos:

* https://apt.postgresql.org/ / https://yum.postgresql.org

* https://dev.mysql.com/downloads/repo/

This way when you upgrade your OS you don't have to worry about suddenly getting a new version (which, in the case of MySQL, may take a long time to convert its database files to the new version format).

How does that work for python/perl/ruby libs etc?