SQL implementation in MariaDB and Percona?

Question

SQL

In MariaDB and Percona, the implementation of the standard is the same as in MySQL, i.e. FIRST() MERGE etc. operators are also not supported? Only the internal mechanisms differ in the type of table engines?
UP Job vacancies sometimes write knowledge of MariaDB, Percona, so what is the peculiarity of "knowledge" if it is a transparent replacement for MySQL - if you know how to work with it - you can with them.

Answer 1

In MariaDB and Percona, the implementation of the standard is the same as in MySQL

In fundamental matters, everything is the same (the application does not have to be changed), but there are still some differences. These are mainly improvements to engines, individual functions and performance optimization.
Full list of differences: https://mariadb.com/kb/en/mariadb/mariadb-vs-mysql...
Compatibility comparison: https://mariadb.com/kb/en/mariadb/mariadb-vs-mysql.. .
https://mariadb.com/kb/en/mariadb/merge/
It is unlikely that such vacancies imply knowledge of MariaDB in principle.
Rather, it is a listing of products that are currently used by the employer, and with which the applicant will definitely have to work, i.e. he expects that using MariaDB won't shock you.
It may be, of course, that their infrastructure is heavily tied to individual MariaDB features.
Maybe this is just a screening out of those who have fallen out of progress and do not even know what the word is.