NoSQL database MongoDB 2 ups the tempo
Version 2.0 of the document-oriented NoSQL database MongoDB has been released by the developers at 10gen. According to a blog posting by Eliot Horowitz, CTO and co-founder of software developers 10gen, the new version should be faster, however it does not represent a major version increment. The changes between 1.8 and 2.0 are, he says, comparable to those between 1.6 and 1.8 – Horowitz is keen to point out that the new version number is simply 1.8 plus 0.2 and therefore does not designate a new major version with major revisions.
Development has focused on speeding up the processing of parallel queries, for example, write locks are now released more quickly. According to Horowitz, this is just a first step in improving the database's concurrency, to which the locks, which had previously been held during a page fault, represent a major hurdle.
Another speed-related change is smaller indices, the size of which has been reduced by about a quarter in MongoDB 2.0, so that they are now frequently small enough to fit in memory. There have also been changes affecting replication – 'replica sets' in MongoDB jargon – which can now be assigned a priority which specifies the sequence of slaves. Tags, used to apply rules for permanently writing data, can now be assigned to individual machines or cluster regions. This enables administrators to ensure that a minimum number of slaves have received data, thereby ensuring that it is treated as persistent.
A complete list of changes can be found in the release notes. The C++ source code and executable versions of MongoDB for Mac OS X, Windows, Solaris and Linux are available for download. MongoDB is licensed under the AGPLv3, while its drivers are are licensed under Apache Licence 2.0.