Assuming you aren’t afraid to write some code, this plugin lets you configure very complex database set-ups.

Initially I moved to using this drop-in to split reads and writes between a master and several read replicas.

Now I’m looking into using this for partitioning my multi-site setup with over 2000 blogs into multiple databases to decrease the size of each, leading to quicker backups and a smaller mean time to recovery, if we ever were unfortunate enough to have to restore from a backup. We also weren’t making use of the replication lag features, and plan on making our newest setup even more fault-tolerant by only sending queries to servers that aren’t lagging behind with their replication.