In MMO's all the information in the game is stored in a database, or in databases. Databases for MMO's are huge, and extremely complex, with hundreds of millions, and probably billions of bits of information. Everything is there, the colour of your hair, and all the items in your house, custom engravings on items, everything.
Those databases have their own servers, and in this case the software is developed by Oracle. As with anything the software for databases improves with new versions, and takes advantage of the features newer hardware has to offer, and hopefully becomes faster, and more stable - bugs are fixed, etc.
So while upgrades for the databases for MMO's don't happen often, at some point it becomes a very good thing to do, and that is what is happening now. The database server and client software is being updated to newer (newest?) versions. And because database server software, and the databases themselves, are so complex, and crucial to the functioning of the game servers, upgrading them is an extremely complex task involving a lot of planning and preparation.
This would have nothing specifically to do with the anti-cheat measures, although the database software affects absolutely everything in the game, so an upgrade would also involve changes to the anti-cheat code - which is already live by the way.