Maxscale "Capability mismatch"

Question

I did a fresh install of Maxscale, and I was trying to set up a Read-Write-Split service on a master-slave mariadb cluster.

When I was trying to connect with DataGrip or DBeaver, I got the following error message: [HY000][1927] Capability mismatch (bdd-master)

But when I use the mysql command line client, it works well.

Do you have any idea of what could be wrong?

Answer 1

It seems that is related to the router used (readwritesplit).

Datagrip send this command when it initiate the connection: set autocommit=1, session_track_schema=1, sql_mode = concat(@@sql_mode,',STRICT_TRANS_TABLES')

It seems that some of theses parameters are not supported by readwritesplit.

Answer 2

MaxScale sends a Capability mismatch error when it detects that the client application requests a protocol capability that one of the backend databases cannot support. In general, this should not happen as MaxScale tries to mimic the backend database and calculates the capabilities so that these sort of mismatches do not happen.

There are some known bugs that can cause this, both in MaxScale as well as old versions of MariaDB and MySQL. Upgrading to the latest possible version of MaxScale should help solve any problems you might see.

Additionally, you should disable the query cache in the database if you are using MySQL as there is a bug in MySQL (and old MariaDB versions as well) that causes these sort of problems to appear.