Manipulating Data
Most of our activities and examples can be reduced to the following: there is a document or documents in a collection that should return some or all the documents in an easy-to-digest format. At their core, the find command and aggregation pipeline are just about identifying and fetching the correct document. However, the capability of the aggregation pipeline is much more robust and broader than that of the find command.
Using some of the more advanced stages and techniques in the pipeline allows us to transform our data, derive new data, and generate insights across a broader scope. This more extensive implementation of the aggregate command is more common than merely rewriting a find command as a pipeline. If you want to answer complex questions or extract the highest possible value from your data, you'll need to know how to achieve the aggregation part of your aggregation pipelines.
After all, we haven't even begun to aggregate any data yet. In...