In this post we’ll examine the following primary impacts of this change:
- concurrency improvements
- impacted features
For example, if a user’s workload commonly involved 24 concurrent
$where queries (each from a unique client), and they have a server with 24 cores, they should expect query execution times to be reduced by (roughly) a factor of 24.
Moving to V8 brings with it a few changes to be aware of when migrating applications to MongoDB version >= 2.4.
Additional Limitations for Map-Reduce and $where Operations
In MongoDB 2.4 a number of global functions and properties available in the shell, such as db, are no longer available to
group. When upgrading to MongoDB 2.4, you will need to refactor your code if you are using any global shell functions or properties that are no longer available.
The following are available to
$where in MongoDB 2.4:
Non-standard Spidermonkey features removed
The following do not work on documents returned from MongoDB queries: