In production, people tend to run it with 3 replicas. MongoDB is a document-based, distributed database. Others include Cassandra, Apache Spark, and many more. NoSQL is a broad term and consists of a variety of database models. Everyone wanted to move their stack to these flexible databases and was talking about how the data needs to move in that direction and so on.Īs the hype began to settle, people started realizing the movement of the stack will help only if they implement it correctly, and for most of them, the shift wasn’t even necessary. Everyone in the industry was talking about them. Mongo belongs to one of those NoSQL databases that disrupted the internet a few years ago. Let’s start by pulling out a few differences between the normal and Mongo database. Here we discuss an introduction to MongoDB Aggregate with syntax, parameters, how it works, and examples with code and output.Today, we are going to talk about Mongo Aggregates: one of the best things that happened to Mongo. After grouping the values, it will perform various operations on grouped data and then return the result. Aggregates used to group the values from the multiple documents with each other. MongoDB aggregate is significant in MongoDB to return a single result of data from multiple documents. We have used an aggregate $sum expression to find the number of employees who have the same salary.ĭb.emp_count.aggregate() Group by and calculate sum: The below example shows we have a calculating the sum of employee numbers which have a matching salary. Below is the data description of the emp_count table are as follows. We have taken an example of an emp_count table to describe examples of MongoDB’s aggregate method as follows.
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