The default MySQL in-memory engine only supports table-locks. This is killing our performance on our session table (using Joomla on the front-end).
Is there a (third-party) engine of an in-memory table that supports row-based locking?
ndb's memory engine does row-level locking: http://dev.mysql.com/doc/refman/5.5/en/memory-storage-engine.html I'm not aware of any other plugin that does.
Have you considered using tmpfs or ramfs for storage?