Berkeley DB, the open source database system frequently used in Linux applications, can now be patched while it's still running. It's the type of "nonstop" feature that's been sought by Berkeley DB users for years and placed at the front of the development road map by Sleepycat, former owner of the embedded database system.
The release today of the 4.5 version, including the nonstop feature, is a sign that Oracle is heeding that road map. Oracle acquired privately held Sleepycat in February for an undisclosed amount.
Skeptics at the time said Oracle would suppress Berkeley DB development in favor of its existing embeddable systems, which include the Times Ten In-Memory database; Oracle Lite, a mobile application database; and Oracle 10g itself. But Oracle's intentions have been made clearer as it let both the former Sleepycat development team and a community of open source contributors continue to add features to the core system. The 4.5 release also includes improvements in multiversion concurrency, or the ability of the system to respond to multiple users who want information from the database at the same time it's being updated.
While it had concurrency in earlier releases, Oracle could have hobbled the system by leaving its concurrent user management at a rudimentary level. Instead, the 4.5 release allows efficient reading from the database even when a long update of its data is taking place, says Rex Wang, VP of embedded systems marketing at Oracle. "The open source community has not changed its perception or use of Berkeley DB," he says.
In addition, Berkeley DB now comes with a replication framework that makes it easier to establish a replication system, where a central database keeps satellite versions in sync. It's a self-maintaining system, meant to be built into an application, configured, and then allowed to run without a database administrator or other human intervention. "All those knobs and dials are still available," Wang says.
The improvements are available for free download from http://www.oracle.com/technology/products/berkeley-db. Oracle makes Berkeley DB available under a commercial license that allows developers to produce proprietary products, or under a free open source license that requires that new applications be given back to the community.