With NuoDB v3.4 , we changed how we package and version our JDBC and Hibernate drivers.

Previously, we have always versioned and packaged the JDBC and Hibernate drivers with the NuoDB database. This tight coupling with the NuoDB database version has led to a lot of confusion on which driver version to use with which release. Customers assumed that the version shipped with the NuoDB database is the only version that can be used with that database version.

This is not correct. In fact, it hasn’t been

As I explained in a previous blog post , sometimes MVCC is not sufficient and an operation needs to block out all other concurrent modifications. NuoDB is able to lock three types of lockable resources: tables, schemas, and sequences. A resource can either be locked in SHARED mode (which still allows record modification, but no metadata modification) or EXCLUSIVE which prevents any concurrent modification.

EXCLUSIVE access is required for DDL that visits all records (various index operations for

Let us imagine a scenario that needs to prevent MVCC write skews...

One transaction increases the salary of everyone in a department by 10%; another transaction inserts a new employee with a salary X. Since the two transactions do not conflict, MVCC does not prevent either of them from committing. After both resolve, the overall salary in the department could be above the budget. To prevent a similar situation, the application developer might want to have exclusive access to the table.

NuoDB 3.2.2 exposes a new type of lock that guarantees exclusive access to a resource

Traditionally, relational databases were designed for scale-up architectures. Supporting more clients or higher throughput required an upgrade to a larger server. Until recently, this meant that implementing a read & write scale-out architecture either required a NoSQL database and abandoning traditional relational database benefits, or relying on sharding and explicit replication. There were no solutions that could scale-out and still provide complete ACID (Atomicity, Consistency, Isolation, and Durability) -compliant semantics. This tension is what inspired the NewSQL