Why does everyone run ancient Postgres versions?

Upgrades are hard. There was no replication in the before times. The original block-level replication didn't work among different major versions. Slony was a painful workaround based on triggers that amplified writes.

Newer PostgreSQL versions are better. Yet still not quite as robust or easy as MySQL.

At a certain scale even MySQL upgrades can be painful. At least when you cannot spare more than a few minutes of downtime.

I've always wondered why Postgres is so insanely popular. I mean it has some nice things like very powerful support for a very comprehensive subset of SQL functionality, but most apps don't need all that.

It really feels like early 1990s vintage Unix software. It's clunky and arcane and it's hard to feel confident doing anything complex with it.

* transactional DDL

* comprehensive transaction model using different modes

* PostGIS and lots of other great extensions

* supports most of the current SQL standard and is clear on interpretation of edge-cases in the documentation

* support for writing stored procedures in any major programming language

* many useful functions regarding dates, sets, ranges, json, xml, ...

* custom datatypes

* extremely thought-out and standardized approach to development: if a feature is included it generally works well in interaction with everything else

* syntax, semantics and performance are all very predictable

* great documentation

Regarding MySQL / MariaDB: MySQL optimized for performance first. Until 2010 the standard-storage-engine MyISAM didn't even support transactions.

PostgreSQL always focused on correctness and stability and then made sure everything performed.

> * custom datatypes

Good in theory. But last time I checked the main libs to connect to pgsql, everything you get back from the database are strings. So you need something in your app to convert those strings to the equivalent data structures.