It's a good question. We built the entire database from the ground up, without any MySQL code. So while we support most of the frequently used features, we don't support everything.
You can get a list of unsupported features and differences from our docs:
Having said that, our customers find that the value that they get out of scale out, fault tolerance, and performance is worth the tradeoffs of not supporting every single MySQL feature.
Honestly, our goal is not to be 100% MySQL compatible. We're aiming to be compatible enough to capture a significant share of existing MySQL installs, but we're really after building a truly scalable relational db.
You can get a list of unsupported features and differences from our docs:
http://docs.clustrix.com/display/CLXDOC/Unsupported+Features
http://docs.clustrix.com/display/CLXDOC/Feature+Differences
Having said that, our customers find that the value that they get out of scale out, fault tolerance, and performance is worth the tradeoffs of not supporting every single MySQL feature.
Honestly, our goal is not to be 100% MySQL compatible. We're aiming to be compatible enough to capture a significant share of existing MySQL installs, but we're really after building a truly scalable relational db.