One of the latest labs releases of Oracle MySQL brings multi source replication. This lifts the limitation found in earlier releases that a MySQL slave can only have one master. To be fair, there were other ways of doing this already: Using a time based switch as described in MySQL High Availability Using the multi source feature in the yet-to-be released MariaDB 10 Using Tungsten Replicator There are many good uses of multi source replication. You could use it to combine data from multiple shards or applications. If MySQL is used with a loadbalancer the most easy to build setup is a 2-way multi master. This makes it possible to use the InnoDB storage engine. Using MySQL Cluster is another alternative, but MySQL Cluster uses the NDB storage engine, and might not be a supported option for your application. A MySQL Cluster setup also needs at least 4 machines to be fully redundant and MySQL Multi Master only needs two machines. There is little intelligence required in the load...

There is a new feature in the MariaDB 10 Beta which caught my eye: support for returning a result set on delete . With a 'regular' DELETE operation you only get to know the number of affected rows. To get more info or actions you have to use a trigger or a foreign key. Anoter posibility is doing a SELECT and then a DELETE and with the correct transaction isolation a transactional support this will work. With the support for the RETURNING keyword this has become easier to do and it will probably bennefit performance and save you a few roundtrips and a few lines of code. There is already support for RETURNING in PostgreSQL. And PostgreSQL has an other nifty feature for which RETURNING really helps: CTE or common table expressions or the WITH keyword. I really hope to see CTE support in MySQL or MariaDB some day. An example from RETURNING and CTE in PostgreSQL: demo=# select * from t1; id | name ----+------- 1 | test1 2 | test2 3 | test3 4 | test1 5 | test2 ...