Use case: some of my SQL syntax depends on MySQL but I realize I made a poor life choice and would rather have transactional DDL and a myriad of better features on postgres.
I thought there were bad blood between Oracle and Amazon?
Likewise, selecting a column not present in a GROUP BY leads to random values being returned.
That hasn't been the default behavior for something like 5 years.
Beyond that the values aren't "random" as much as "one of the values from the set" which can be a useful feature in cares where you want any of the values and don't want the performance hit that comes with using an aggregate function particularly on very very large sets.
https://github.com/dimitri/pgloader
pgloader \
mysql://user:password@mysql:3306/database \
postgresql://postgres:root@localhost:5432/postgres
And it would need to replicate the specialised data types like utf8mb3.
To use PostgreSQL features (such as JSON datatype) would presumably need a separate data connection and transaction, because if it isn’t implemented by MySQL, then the syntax wouldn’t be supported by Babelfish.
You would get some wins, but you don’t get a blend of the best of both.
Having to use MySQL/MariaDB after usually dealing with PostgreSQL always feels like such a downgrade.
Just spitballing, sorry, I love FDWs.