Over a million developers have joined DZone.

Mongoid Collection Snapshot - Great for MapReduce

DZone 's Guide to

Mongoid Collection Snapshot - Great for MapReduce

· Database Zone ·
Free Resource
Another fine open-source contribution from @aaw, mongoid_collection_snapshot: easy maintenance of collections of processed data in MongoDB with the Mongoid ODM.



This turned out to be extremely useful in many map-reduce scenarios where we do lengthy computations that output data that is used as a complete and consistent set. For example, calculating average prices across ranges of items (the example in the documentation). Another good use can be for tags stored as arrays of strings – you want to know how many items are tagged with a given entry. We can now take my incremental tag count map-reduce and replace it with a much more trivial implementation that uses this gem.


Published at DZone with permission of

Opinions expressed by DZone contributors are their own.

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}