What is aggregation framework in MongoDB?

The MongoDB Aggregation Framework is a way to query the data from MongoDB. It helps us to break the complex logics into a simple set of sequential operations. Just like a waterfall model, Output from one stage is fed as an input for the next stage until the desired result is achieved.

What is the MongoDB aggregation pipeline?

The MongoDB aggregation pipeline consists of stages. Each stage transforms the documents as they pass through the pipeline. Pipeline stages do not need to produce one output document for every input document. For example, some stages may generate new documents or filter out documents.

Where is aggregate in MongoDB?

The first method has two steps first is a query to the database and second is find the length of resulting array. But second method(aggregate) gives the end result by the use of a query. By the use of below MongoDB query, we will find the final result.

What is the purpose of the aggregation pipeline in MongoDB?

The pipeline provides efficient data aggregation using native operations within MongoDB, and is the preferred method for data aggregation in MongoDB. The aggregation pipeline can operate on a sharded collection. The aggregation pipeline can use indexes to improve its performance during some of its stages.

How to group MongoDB?

Mongodb group by multiple fields using Aggregate operation First, the key on which the grouping is based is selected and then the collection is divided into groups according to the selected key value. You can then create a final document by aggregating the documents in each group.

What is aggregate MongoDB?

In MongoDB, aggregation can be defined as the operation that is used for processing various types of data in the collection , which returns a calculated result. The concept of aggregation mainly clusters out your data from multiple different documents which are then used and operates in lots of ways (on these clustered data) to return a combined result which can bring new information to the existing database.

How big is a document in MongoDB?

MongoDB stores all documents as BSON, which is just a binary encoding of the good old JSON format. The maximum BSON document size in MongoDB is 16 MB. Which is nothing when we want to store large files like videos and songs. They might easily exceed the limit.