SELECT query returns legacy data My program does r/w operations on a MariaDB table. There are circumstances why it has to do it in concurrent processes. That's why it does it with multiple connections. After a write (UPDATE query) operation, the then triggered read operation receives legacy values. 
Question is if there is any query or other feature which makes all connections refreshing their data. A reconnect of the reader is actually working, but honestly a bad workaround.

There is no cache activated. And even if, the description says that an UPDATE will clear the affected sections in the cache.
I'm pretty new to MariaDB, is there any part of the general concept that I miss here?
The general concept to consider with these issues is "transaction isolation level".

I believe the most plausible explanation with MariaDB would be that both writers and readers work in non-autocommit mode (either autocommit=0 in my.cnf or set explicitly where application opens new connection). In this case, you can give the reader sessions access to newly updated data by issuing their own local commit; command instead of full re-connect.