Top 40 MongoDB Interview Questions and Answers

Bucket collection is a specialized form of collection where delinquent accounts are grouped into buckets based on their age or severity.

• Normal collection involves the process of collecting outstanding payments from customers.

• Bucket collection categor...read more

MongoDB is better suited for handling unstructured data and offers better scalability and performance compared to MySQL.

• MongoDB is a NoSQL database that allows for flexible and dynamic schema design.

• MongoDB is better suited for handling large amounts...read more

Mongo query to increase age by 20% for documents with age field

• Use $exists operator to filter documents with age field

• Use $mul operator to increase age by 20%

• Example: db.users.updateMany({ age: { $exists: true } }, { $mul: { age: 1.2 } })

Mongoose provides a higher-level abstraction over MongoDB, simplifying data modeling and validation.

• Schema Definition: Mongoose allows defining schemas for data models, ensuring data consistency. Example: const userSchema = new mongoose.Schema({ name...read more

The number of collections refers to the total number of outstanding debts that a loan adviser is responsible for managing.

• Collections are typically categorized by the type of debt, such as credit card debt, student loans, or mortgages.

• Loan advisers w...read more

The $shared operator in MongoDB is used to perform set intersection between arrays.

• Used to find common elements between arrays

• Returns an array containing elements that appear in all input arrays

• Syntax: { $shared: { arrays: [ , , ... ] } }

• Example: { $...read more

Use GridFS to save large files in MongoDB database.

• GridFS is a specification for storing and retrieving large files in MongoDB.

• It divides the file into smaller chunks and stores them as separate documents.

• GridFS provides a way to query and retrieve t...read more

Create a docker file to make mongodb available for developers

• Use the official MongoDB Docker image as the base image

• Expose the default MongoDB port (27017)

• Set up any necessary environment variables or configurations

• Build the Docker image using the Do...read more

MongoDB is preferred over SQL for its flexibility, scalability, and ease of use in handling unstructured data.

• MongoDB is a NoSQL database, making it easier to work with unstructured data compared to SQL.

• MongoDB is schema-less, allowing for more flexi...read more

To connect to MongoDB using Javascript, you can use the official MongoDB Node.js driver.

• Install the MongoDB Node.js driver using npm: npm install mongodb

• Require the MongoDB Node.js driver in your Javascript file: const MongoClient = require('mongodb'...read more

Creating a MongoDB model in Node.js for data storage and retrieval.

• Define a schema using Mongoose library

• Create a model using the schema

• Use the model to interact with the MongoDB database

Optimising MongoDB Database involves indexing, proper query optimization, sharding, and using the right data model.

• Create indexes on fields frequently used in queries to improve query performance.

• Use the explain() method to analyze and optimize query...read more

To connect to MongoDB from NodeJS backend, use the 'mongodb' package and the 'MongoClient' class.

• Install the 'mongodb' package using npm: npm install mongodb

• Require the 'mongodb' package in your NodeJS file: const MongoClient = require('mongodb').Mon...read more

Over-indexing in MongoDB can negatively impact performance by increasing memory usage and slowing down query execution.

• Over-indexing can lead to increased memory usage as each index consumes memory.

• Having too many indexes can slow down write operatio...read more

To connect MongoDB with a database, you need to use the MongoDB URI and a MongoDB client library.

• Use the MongoDB URI to specify the connection details such as host, port, username, password, and database name

• Install a MongoDB client library like Mong...read more

MongoDB is a NoSQL database while the relational model is based on tables and SQL.

• MongoDB is schema-less, allowing flexible and dynamic data structures.

• Relational databases use a fixed schema with predefined tables and columns.

• MongoDB uses a document...read more

Different databases have their own strengths and weaknesses.

• MongoDB is a NoSQL database that is great for handling unstructured data.

• PostgreSQL is a relational database that is known for its stability and ACID compliance.

• MySQL is a popular open-sourc...read more

To fetch data from MongoDB, use the find() method with optional query parameters.

• Use the find() method to retrieve data from a MongoDB collection

• You can pass query parameters to filter the results

• Use the findOne() method to retrieve a single document

Key considerations include data modeling, indexing, sharding, and replication.

• Consider the data model carefully to ensure it fits the application's needs.

• Use indexing to improve query performance.

• Plan for sharding to distribute data across multiple s...read more

MongoDB is scalable due to its ability to horizontally partition data across multiple servers.

• MongoDB uses sharding to distribute data across multiple servers.

• Sharding allows for horizontal scaling by adding more servers to the cluster.

• MongoDB also s...read more

CRUD operations in MongoDB include create, read, update, and delete operations on documents in a collection.

• Create: db.collection.insertOne()

• Read: db.collection.find()

• Update: db.collection.updateOne()

• Delete: db.collection.deleteOne()

To join in MongoDB, you can use the $lookup aggregation stage to perform a left outer join between two collections.

• Use the $lookup aggregation stage in MongoDB to join collections.

• Specify the localField and foreignField to define the fields to join o...read more

Connecting to MongoDB involves using a driver to establish a connection and perform database operations.

• Install MongoDB driver: Use npm to install the MongoDB driver in Node.js: `npm install mongodb`.

• Import the MongoDB client: In your code, import th...read more

MongoDB is a document-oriented database while Cassandra is a column-family database.

• MongoDB is better suited for complex queries and data modeling.

• Cassandra is better for write-heavy workloads and high availability.

• MongoDB has a flexible schema while...read more

Handle large datasets in MongoDB by sharding, indexing, and using aggregation pipelines.

• Use sharding to distribute data across multiple servers for horizontal scaling.

• Create indexes on frequently queried fields to improve query performance.

• Utilize ag...read more

They are used in MongoDB aggregation pipeline to perform various operations like joining, filtering, projecting, etc.

• Used in MongoDB aggregation pipeline for data manipulation

• Perform operations like joining, filtering, projecting, etc.

• Help in combini...read more

Aggregate operators in MongoDB are used for data aggregation and manipulation.

• Some aggregate operators in MongoDB include $sum, $avg, $min, $max, $push, $addToSet, $first, $last, $project, $match, $group, $sort, $limit, $skip.

• Example: db.collection.a...read more