32-bit limitations



32-bit MongoDB processes are limited to about 2 gb of data.  This has come as a surprise to a lot of people who are used to not having to worry about that.  The reason for this is that the MongoDB storage engine uses memory-mapped files for performance.

By not supporting more than 2gb on 32-bit, we’ve been able to keep our code much simpler and cleaner.  This greatly reduces the number of bugs, and reduces the time that we need to release a 1.0 product. The world is moving toward all 64-bit very quickly.  Right now there aren’t too many people for whom 64-bit is a problem, and in the long term, we think this will be a non-issue.