Release Notes: New features include automatic initialization of replication clients, degree 2 transaction isolation, and native support for sequence number generation. Mutex statistics can now be easily gathered and recorded. The replication election process is now Paxos compliant. Support for Itanium2 chips running Windows XP was added. The Java API was enhanced to be nearly identical to that of the Java Edition. In-memory transaction logs were added, allowing in-memory databases.
Release Notes: The first 5.3 release came out a few month ago. One of the main highlights was support for the Android platform. 5.3.21 is the second release. This is mainly a bugfix release, but it does include one feature which is potentially very interesting, support for Oracle JDK7.
Release Notes: New features include an online backup command for SQL, VACUUM (which does not require the database to be quiescent), encryption, BFILE, ADO.NET, iOS/iPhone/iPad support (in addition to existing support for Android), a new command line tool called "db_replicate" which will turn non-HA applications into HA/replicated applications with no new code, performance improvements, and lots of other features.
Release Notes: Increased Performance: improved concurrency for multi-threaded applications on SMP systems. A new db_sql tool: automatic generation of Berkeley DB application code from SQL for faster development and migration. New APIs: support for C#/.NET and the C++ Standard Template Library (STL).
Release Notes: The lock manager may now be partitioned, improving performance on some SMP and CMP systems. Optional pre-zero log files. Replications across different endian CPUs. Replication can manage the master node via leases. The Java/JNI API now supports the Direct Persistence Layer (DPL). failchk() and other methods related to post-process failure database cleanup have been improved.
Release Notes: Non-stop upgrades for replicated systems: customers can upgrade/patch the database without taking the entire system down. Multi-version concurrency control (MVCC) allows read transactions to proceed without being blocked by write transactions, therefore improving concurrency and performance. Replication framework is a pre-built, out of the box framework that makes it faster and easier for developers to build replicated apps.