MONGODB GROUP() VS MAPREDUCE VS AGGREGATION Framework2022-07-21
The group() command, Aggregation Framework and MapReduce are collectively aggregation features of MongoDB. group(): Group Performs simple aggregation operations on a collection documents. Group is similar to GROUP_BY in mysql. Output format : Returns result set inline. Sharding: Its not support in shared environment. Limitations:
Output format: MapReduce provides inline, new collection, merge, replace, reduce output options. Sharding: Its supports for both shared and non-shared collections as input and output.If output collection does not exists then MapReduce creates and shards the collection on _id field. Limitations:
Output format: Returns result set inline. Sharding: Its supports for both shared and non-shared input collections.When operating with shared collections,It push all operations up to first $group or $sort to all shards,The remaining operations from first $group or $sort are run as second pipeline on shared results.