A great addition to MariaDB would be able to validate JSON schemas. MySQL already have this implemented as follows:
Validates a JSON document against a JSON schema. Both schema and document are required. The schema must be a valid JSON object; the document must be a valid JSON document. Provided that these conditions are met: If the document validates against the schema, the function returns true (1); otherwise, it returns false (0).
Since MariaDB is great and it allows the use of UDFs and deterministic functions on constraints something like this would be awesome:
The word schema should be replaced by a string representing a valid JSON schema.