See the MongoDB documentation for more information. Therefore, $sortB圜ount simply counts the numbers from the document provided to it, which included just one dog. This time only one dog is in the document passed to $sortB圜ount, because the first pipeline stage removed dogs over a certain weight. Here’s another example, but with added filtering criteria. Suppose we have a collection called pets with the following documents: Right-click anywhere in the Pipeline section and Stage editor and choose Save > Create view from this aggregate query. Aggregation operations group values from multiple documents together, and can perform a variety of operations on the grouped data to return a single result. Views are a great shortcut to accessing the data you need without having to run the same queries. Aggregations operations process data records and return computed results. The id field of each output document contains the unique group by value. The documents are sorted by count in descending order. MongoDB - Aggregation, MongoDB - Aggregation. Groups input documents by the specified id expression and for each distinct grouping, outputs a document. a count field containing the number of documents belonging to that grouping.an _id field containing the distinct grouping value, and.In MongoDB the $sortB圜ount aggregation pipeline stage groups incoming documents based on the value of a specified expression, then computes the count of documents in each distinct group.Įach group is output in its own document, which consists of two fields:
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