indexable JSON datatype in MySQL/MariaDB In PostgreSQL 9.4 there is a JSONB datatype which allows you to index on fields in the stored JSON objects. Does MySQL/MariaDB have an equivalent?

I'm specifically interested in the MariaDB Galera cluster, but am open to any MySQL-family answers.
You can do this in MySql 5.7. What you are looking for is adding an index over Generated Columns. You can find an example here:
http://mysqlserverteam.com/inline-json-path-expressions-in-mysql-5-7/