Marko Sutic's Database Blog

ProxySQL is a great high availability and load balancing solution and it is mostly used for such purposes. But ProxySQL offers much more.
One of the nice features is the throttling mechanism for queries to the backends.
Imagine you have a very active system and applications are executing queries at very high rate, which is not so unusual nowadays. If just one of the queries slows down you could easily end up with many active sessions running the same query. Just one...

Galera Cluster is a virtually synchronous multi-master replication plug-in. When using Galera Cluster application can write to any node and transactions are then applied to all serves via row-based replication events.
This is built-in Mysql row-based replication which supports replication with differing table definitions between Master and Slave....

Galera Cluster is great solution for application clustering but it has some limitations. One of the most critical limitations is how Galera Cluster performs model changes.
From Galera Cluster documentation:http://galeracluster.com/documentation-webpages/clusterstallonalter.html...

Few days ago we had performance problem with one of our main application views. This was complex view that used a lot of aggregate function. Functions were used to transpose rows into columns.
When developer added few more aggregate functions for a new columns, query performance changed significantly and we had performance problem....