Yeah MariaDB got 'dynamic columns' first, which iirc supported key values but not arrays, and then MySQL added a more complete 'json' data type, so the exact functionality differs by flavour and version.
The postgres support is simply nicer to use and more powerful, e.g. the indexing.
But if your RDBMS is any fairly-recent version of MariaDB or MySQL, you can use JSON too.
Of the top of my head, the thing I find most griping about the MySQL syntax is you have to do
thing->>"$.key"
instead of postgres-style
thing->>'key'
Whereas what I really want to be able to do is
thing.key
But most of the consumers of these modern 'dynamic columns' are apps and then it all really matters less if you don't spend all your days at the sql prompt writing stuff by hand.
Yeah I seem what I wrote could be ambiguous, but in that first para I was meaning to compare MariaDB and MySQL, not claim that MariaDB beat PostgreSQL.
