See the full index of this page for a complete list of changes included in 1.6.
MongoDB 1.6 is a drop-in replacement for 1.4. To upgrade, simply shutdown mongod then restart with the new binaries.
Please note that you should upgrade to the latest version of whichever driver you’re using. Certain drivers, including the Ruby driver, will require the upgrade, and all the drivers will provide extra features for connecting to replica sets.
Replica sets, which provide automated failover among a cluster of n nodes, are also now available.
Please note that replica pairs are now deprecated; we strongly recommend that replica pair users upgrade to replica sets.