MongoDB Database

MongoDB Certification

MongoDB is a cross-platform document-oriented database application that is open source. MongoDB is a NoSQL database application that works with JSON-like documents and optional schemas. NoSQL databases replace traditional relational databases. Working with massive sets of distributed data is a breeze with NoSQL databases. MongoDB is a database management system that can store and retrieve document-oriented data. With auto-sharding, MongoDB was intended for high availability and scalability. MongoDB is based on the architecture of collections and documents rather than tables and rows, as with Relational Databases. The rows (or documents, as MongoDB refers to them) in MongoDB do not require a schema to be created beforehand.

When Dwight Merriman and Eliot Horowitz were designing web applications at DoubleClick, an online advertising startup now owned by Google Inc., they ran into development and scalability challenges with standard relational database systems. In 2007, Merriman and Horowitz assisted in the formation of 10Gen Inc., a company dedicated to commercializing MongoDB and related products. In 2013, the firm was renamed MongoDB Inc., and in October 2017, it went public under the ticker symbol MDB. The database’s name was taken from the word gargantuan to convey the idea of supporting vast volumes of data.

Free MongoDB Practice Test Online

Mongo DB’s ad-hoc queries, indexing, load balancing, aggregation, server-side JavaScript execution, and other features can be used by businesses. MongoDB, like other NoSQL databases, does not need preset schemas. It can store any information. This allows users to create any fields in a document, allowing MongoDB databases to scale more easily than relational databases. MongoDB’s horizontal scalability is a key feature that makes it a good choice for enterprises with big data applications. Furthermore, sharding enables the database to share data across a group of servers. Newer MongoDB versions additionally permit the formation of data zones based on a shard key.

MongoDB Realm App Group

Realm is a mobile-to-cloud synchronization solution faster and more scalable than SQLite. Realm is a free, open-source mobile database that competes with CoreData and SQLite. It’s a software development platform for data-driven, modern apps. A realm may be used to create apps for mobile, web, desktop, and IoT. Realm is an embedded object-oriented database that enables you to create real-time, offline-first apps. Atlas App Services, a secure backend that can sync data between devices, authenticate and manage users, and conduct serverless JavaScript operations, is also accessible through its SDKs. Realm provides open-source SDKs for major programming languages, frameworks, and platforms. The following are some of the benefits of using Realm:

  • It’s easy to get started and grow.
  • Syncing from your phone to the cloud is built-in.
  • Lightweight and quick

Sort by Date MongoDB

MongoDB sort by date is used to sort the date field in ascending or descending order. The sort method in MongoDB can be used to sort the date. The aggregate method can also be used to sort the date and timestamp fields in MongoDB. We must supply a value of -1 or 1 to the date column to sort the data. If we pass a -1 value to the date field, the result will be displayed in descending order, whereas if we pass a 1 value to the date field, the result will be displayed in ascending order. The sort() method in MongoDB is used to sort data. The sort() method is made up of two main components. The fields to be sorted and the sort order is the building blocks. The syntax for sorting by date in MongoDB is listed below.

  • db.collection_name.aggregate ( { $sort: { name_of_date_field : -1 (Display the date in descending order) } } )
  • db.collection_name.aggregate ( { $sort: { name_of_date_field : 1 (Display the date in ascending order) } } )
  • db.collection_name.find ().sort ( { name_of_date_field : 1 (Display the date in ascending order)} )
  • db.collection_name.find ().sort ( { name_of_date_field : -1 (Display the date in descending order) } )

DynamoDB vs MongoDB

MongoDB and DynamoDB are similar in terms of functionality and features. When it comes to choosing between the two, there are a few crucial considerations. MongoDB allows you to configure the database to run on any system, container, or on-premise deployment, as well as any cloud provider. DynamoDB is a completely managed database that allows customers to immediately begin utilizing the database because AWS handles all scaling, availability, and upgrades. A multi-region, highly available database can be provisioned with only a few clicks, substantially reducing the requirement for dedicated infrastructure administration.



  • DynamoDB does not support multiple operations in a single transaction.
  • Only on AWS is this service available.
  • Because DynamoDB is a web service supplied by, it is incredibly simple to set up and install.
  • It’s written in Java and only supports a handful of programming languages.
  • Storage choices for certain data types are limited.
  • Only key-value queries are allowed.
  • Maximum document size of 400 KB is allowed.
  • Schema-type storage is strictly forbidden.
  • MongoDB allows you to read and write to the same documents and fields in a single database transaction.
  • You can use it anywhere.
  • MongoDB is a challenging database to set up and install.
  • It’s compatible with Linux, OS X, Solaris, and Windows.
  • There is no security setup by default.
  • Language for complex queries
  • It’s written in C++ and works with a variety of programming languages.
  • It is schema-less but supports storage of schema-type data.

Install MongoDB

There are two server editions of MongoDB: Community and Enterprise. The instructions to install it on Windows are as follows:

  • The MongoDB MSI Installer Package is available for download.
  • Use the Installation Wizard to set up MongoDB.
    • Make sure you’re logged in as an administrator user.
    • To begin the installation process, click Next.
    • Accept the license agreement before moving on to the next step.
    • Choose the Complete setup option.
    • Select “Run service as Network Service user”.
    • Click Next after deselecting Mongo Compass.
    • To begin the installation process, click Install.
    • To finish the installation, click Finish.
  • To store our databases, we’ll need to create data folders.
    • Using Explorer, navigate to your computer’s C Drive and create a new folder called data.
    • Make a new folder called DB inside the data folder you just made.
  • Set up Mongo and Mongod Alias Shortcuts
    • Launch Git Bash on your Hyper terminal.
    • Using the following command, change the directory to your home directory:  cd ~
    • Create a file named .bash_profile with the following command: touch .bash_profile
    • Using vim, open the freshly created .bash_profile using the command:  vim .bash_profile
    • To enter insert mode in vim, press the I key on the keyboard.
    • Go to C Program Files MongoDB Server in your explorer. Now you should be able to see the MongoDB version.
    • Copy and paste the following code into vim, replacing the 4.0 with the version you see in explorer.

                       alias mongod=”/c/Program\ files/MongoDB/Server/4.0/bin/mongod.exe”

                      alias mongo=”/c/Program\ Files/MongoDB/Server/4.0/bin/mongo.exe”

  • To exit insert mode, press the Escape key on your keyboard. After that, type :wq!
  • Check to see if the setup was successful.
    • Close the Hyper terminal now open and exit the application.
    • Re-establish Hyper.
    • In the Hyper Terminal, type the following commands:

                      mongo –version

Delete Document MongoDB

MongoDB is the most widely used NoSQL database, and it stores data in the form of documents. The documents are essentially JSON objects that can be deleted in various ways. We can also delete these documents using the MongoDB Compass or MongoDB Atlas graphical user interfaces. To remove documents from a collection, use the following methods in the MongoDB shell:

  • Use db.collection.deleteMany() 
    • The db.collection.delete method is used to delete a collection from a database. The db.collection.deleteMany() function is quite similar to the db.collection.remove() method, but with the added feature of deleting a large number of documents.
  • Use db.collection.deleteOne() 
    • The db.collection.deleteOne() method is similar to the db.collection.remove() method, however it only deletes one document.
  • The db.collection.remove() method
    • We can delete all of the documents, some of the documents, or just one document using this procedure. We specify a parameter in it, and the amount of papers removed is determined by it.
  • The delete command
    • The delete command is equivalent to the remove() method in terms of functionality. The delete command is used by the remove() method.

MongoDB Jobs

The MongoDB community is reshaping industries and empowering developers to create incredible products that people use daily. MongoDB careers come in various shapes, sizes, and needs. The MongoDB corporation is also known as the 10gen corporation, its initial name. The ideal applicants must agree with and connect with the MongoDB organization’s basic principles. They should also possess the qualities and skills listed below, which are only generalized and may change based on the position you are looking for. Here are some of the MongoDB job openings:

  • Account Executive
  • Cloud Security Engineer
  • Full Stack Developer
  • Software Development Engineer
  • Technical Lead
  • Senior Consulting Engineer
  • Analytics Manager
  • Animator / Motion Graphics Designer
  • Backend Developer
  • MongoDB DBA
  • Senior Solutions Architect
  • Associate Commercial Counsel
  • Customer Success Manager
  • Sr. Data Engineer
  • VP of Sales Enablement
  • Associate HR Shared Services
  • Project Associate – Professional Services
  • Database Administrator
  • Technical Services Engineer
  • Business Operations Associate

MongoDB Sort

The order in which the query delivers the matching documents from the provided collection is specified by the sort() method. Before getting any documents from the database, you must apply this method on the cursor. It takes as an argument a document with a field: value pair that sets the sort order of the result set. The values 1 and -1 indicate whether the sort should be ascending or descending.


db.Collection_Name.sort({filed_name:1 or -1})

The following are some critical points to know when using the MongoDB Sort() Method:

  • To return the first x documents, use the limit() function in conjunction with the MongoDB Sort() method, where x is the provided limit.
  • If Index Scanning is unsuccessful in determining the sorting order, MongoDB uses the Top-K Sorting method to determine the sorting order.
  • MongoDB normally uses a Stable Sort unless you’re sorting on a field with duplicate values. A Stable Sort is a type of sorting that produces the same result every time the same data is sorted.

Index of Array MongoDB

The $indexOfArray aggregation pipeline operator in MongoDB searches an array for an occurrence of a provided value and returns the first occurrence’s array index. Returns the array index (zero-based) of the first occurrence of a provided value after searching an array for an occurrence of a specified value. Returns -1 if the value cannot be found. The syntax is as follows:

{ $indexOfArray: [ <array expression>, <search expression>, <start>, <end> ] }

  • The array to search is <array expression>.
  • The value you want to find in the array is the <search expression>.
  • <start> is an optional input that defines a starting point in the array for which to search. Any valid expression that yields a non-negative integral number can be used.
  • <end> is an optional input that indicates the search’s final index position. Any valid expression that yields a non-negative integral number can be used.

MongoDB Connection String

The MongoDB connection string is a connection format for connecting to a MongoDB database server. To connect to the database server, we utilize the username, hostname, password, and port parameters. We can’t connect to the database server without a connection string; we need a connection string to connect to the database server. We must connect to our database server using the “mongo” and “mongodb” commands, and we must define database connection string information using the “mongodb” command. MongoDB Connection String Syntax:

mongodb:// [ name_of user: password_of_database_user] host_name1 [port_no_of_host1], host_name2 [port_no_of_host2],… host_nameN [port_no_of_hostN] [/] database_name [?options]

MongoDB Journal and Oplog

The MongoDB storage engine layer has a concept called journal. MongoDB primarily supports storage engines such as mmapv1, wiredtiger, mongorocks, and others, all of which offer journal settings. All data writes and reads in MongoDB are eventually tuned to the storage engine layer’s interface for storing and reading data. The journal is a data storing technique used by the storage engine.

At the MongoDB master-slave replication level, oplog is a concept. Oplog is used to keep data synchronized between nodes in a replication set. Data is written to the Primary by the client. An oplog is created after the primary write the data. The Secondary is influenced by the Primary (or other Secondary). Replay the oplog to guarantee that every node in the replica set has the same data. In MongoDB, an oplog is a standard capped collection. Oplog is treated as regular data by the storage engine.

MongoDB Unwind

$unwind in MongoDB is a valuable tool for conducting aggregation. To deconstruct an array field in a document and create distinct output documents for each item in the array, use the MongoDB $unwind operator. MongoDB $unwind breaks down complex documents into smaller chunks, making them easier to read and comprehend. This also allows us to conduct additional operations on the output, such as grouping and sorting. IncludeArrayIndex and preserveNullAndEmptyArrays are two optional arguments that can use with the $unwind operator.


{ $unwind: } 

MongoDB UpdateOne

You can use the updateOne() method to update a single document that meets a criterion. The updateOne() method in MongoDB updates the first matching document in the collection based on the query. The _id field’s value does not change when updating your document. This method can update and add new fields to a single document at a time.

The following is the updateOne() method’s syntax:

db.collection.updateOne(filter, update, options)


  1. filter: The update selection criteria are the same for the find() method.
  2. document: A document or pipeline containing changes to be applied.
  3. options: Options for updating behavior can be found in May. Upsert, writeConcern, collation, and other operations are included.

MongoDB Question and Answer

MongoDB is a NoSQL database management system that is free and open source. NoSQL databases replace traditional relational databases. Working with massive sets of distributed data is a breeze with NoSQL databases. MongoDB is a database management system that can store and retrieve document-oriented data.

MongoDB is not an ACID-compliant database.

MongoDB is a document-oriented database that uses a non-relational approach.

MongoDB is a NoSQL database management system that is free and open source. NoSQL databases replace traditional relational databases. Working with massive sets of distributed data is a breeze with NoSQL databases. MongoDB is a database management system that can store and retrieve document-oriented data.

MongoDB is used by over 33,000 people in over 100 countries. There have been over 1.5 million MongoDB University registrations, and the MongoDB database platform has been downloaded over 240 million times.

From the fiscal year 2019 to the fiscal year 2021, Mongodb, Inc. has filed 134 labor condition applications for H1B visas and three labor certifications for green cards. Among all visa sponsors, Mongodb was rated 42nd.

With simple configuration choices, you can get started with a MongoDB development sandbox on MongoDB Atlas for free. You don’t need a payment card to create a cluster, and you can use it to learn more about MongoDB Atlas, MongoDB’s database-as-a-service platform.

To create a capped collection or a new collection with document validation, call database. createCollection(). The database command create is wrapped in db.createCollection().

MongoDB installation guides are available for the following platforms, both Community and Enterprise Editions:

Yes, MongoDB is a free and open source database.

Industry leaders with well-known brand names, such as The Weather Channel, City of Chicago, Bosch Software Innovations, and Chico’s FAS, Inc., are among the users.

A software development team can gain a lot of advantages by using MongoDB. Its adaptable schema makes it simple to evolve and store data in a form that programmers can understand. MongoDB is also designed to scale quickly and has all of the essential capabilities of a modern database, such as transactions.

MongoDB is incredibly scalable.

The insertOne() function on a MongoCollection object can be used to add a single document to a collection.

  • Download MongoDB Community Server from the MongoDB Download Center.
  • You will be given a TGZ file ( with extension .tgz) after the download is finished. Now, extract this file to the desired location on your computer.
  • We now need to set an environment variable or path to execute mongo shell. In the.bash profile file, you can specify your path. If you’re using Mojave OS or earlier, you can set your path in the.zprofile file, or if you’re using Catalina or later, you can set your path in the.zprofile file.
  • Before running mongod, we’ll construct a folder or directory that will house all of the data that mongod will handle. Or, to put it another way, 
  • Now we’ll run mongod using the data directory path. The database server provided by MongoDB is mongod in this case. We’ll make a data directory for the mongod process to store data in.
  • Now, we’ll use the mongo shell to connect to our server (mongod). So, close the mongod terminal window and open a new one with mongo, and our mongo shell will now connect to mongod successfully.

You must use MongoDB’s find() method to query data from a MongoDB collection.

A “$” is reserved for operators, according to the documentation. When it comes to the group operator, values must be preceded by a dollar. These aren’t operators; they’re just values.

MongoDB Atlas is a fully managed cloud database that takes care of all the details of deploying, monitoring, and recovering your installations on your preferred cloud service provider (AWS, Azure, and GCP). The best approach to deploy, run, and scale MongoDB in the cloud is with MongoDB Atlas.

MongoDB is based on a scale-out architecture, which has grown popular among developers for creating scalable systems with changing data schemas. MongoDB makes it simple for developers to store structured and unstructured data as a document database. It stores documents in a JSON-like manner.

To start MongoDB, open a Command Prompt and type mongod.exe, then navigate to your MongoDB Bin folder and type mongod. This will start the MongoDB main process and display the waiting for connections message in the console.

A shard is a single MongoDB instance that stores a part of the data that has been sharded. Shards can be deployed as replica sets to boost availability and offer redundancy. A complete data set is created by combining numerous shards.

If you’re already connected to MongoDB, you may check the version with the db.version() method.
This function returns the mongod or mongos instance’s version.

Use one of the following methods to stop the MongoDB service manually: At the command prompt, type /etc/init. d/mongodnetbrain stop. At the command prompt, type service mongodnetbrain stop.

MongoDB is faster than MySQL because of its capacity to manage vast amounts of unstructured data when it comes to speed. It processes large amounts of unstructured data via replica replication and source replication, and it allows you to use numerous data types, which is better than MySQL’s rigidity.

In MongoDB, a sharded cluster is referred to as a MongoDB cluster.

It allows customers to visually monitor their database to understand the sorts of queries that are being run, allowing their engineers to identify and optimize the bottlenecks in their application.

The main key-foreign key relationship is not supported by MongoDB.

MongoDB Compass is a graphical interface that allows you to browse over the data stored in a MongoDB database. It eliminates the need to memorize the names of unusual databases or collections, and it allows you to quickly go to any database or collection on your MongoDB server.

Splunk does not utilize a database to store its data because it relies heavily on indexes. However, it does use MongoDB to support certain internal functions like the kvstore.

MongoDB is a robust and detailed database management tool, so you’ll probably need approximately three weeks to get up to speed.

  • Start MongoDB without authentication.
  • Use the mongo shell to connect to the server.
  • Create the administrator user. 
  • In the mongod configuration file, enable authentication. 
  • Log in as the user administrator and connect.
  • Finally, add as many users as you need.
  • The first step is to set up the repository. 
  • On Fedora, install MongoDB. 
  • Launch the MongoDB Service. 
  • Log in to the MongoDB Shell
  • Get the MSI Installer Package for MongoDB.
  • Use the Installation Wizard to set up MongoDB. 
  • Make the data folders where we’ll keep our databases. 
  • Create Mongo and Mongod Alias Shortcuts 
  • Double-check that the setup was successful.

The updateOne() and updateMany() methods can add, update, or remove array components based on the criteria you specify. To update several arrays in a collection, the updateMany() function is recommended.

MongoDB is a cross-platform document-oriented database application that is open source.

MongoDB does not require a relational database management system (RDBMS), it offers an elastic data storage paradigm that allows users to store and query multiple data types easily.

MongoDB is a non-relational database management system based on documents. An object-based system is another name for it. It was created to replace MySQL’s structure as a more convenient approach to interacting with data. On the other hand, MySQL is a table-based database (or an open-source relational database).

A document database is MongoDB.

Highly transactional systems, or those in which the data model is created in advance Systems with a tight coupling

When compared to nonrelational NoSQL databases like MongoDB, Google uses CloudSQL databases, which are relational databases.

MongoDB version 4.0 added support for multi-document ACID transactions in 2018, while version 4.2 added support for distributed ACID transactions in 2019. The document model in MongoDB allows you to store related data in a single document.

Before adding a new document to the database, MongoDB produces a unique ObjectID identification allocated to the _id column of that document before adding a new document to the database. In many circumstances, MongoDB’s default unique identifiers will satisfy application needs.

To check if mongod is up and running (you need to be root to do this, or prefix everything with sudo). It’s worth noting that the grep command will always appear as a separate process.

It was running fast. Queries for primary keys or indexes should only take a few milliseconds. Without indexes, queries are subject to collection size, system specifications, and other factors.

Data is saved in MongoDB as documents. MongoDB saves these documents in JSON (JavaScript Object Notation) format. Embedded fields in JSON documents allow related data and lists of data to be kept in the document rather than in an external table. Name/value pairs are used to format JSON.

The content saved in arrays is indexed by MongoDB using multikey indexes. MongoDB creates separate index entries for each element of an array when you index a field that stores an array value. These multikey indexes allow queries to select documents containing arrays by matching one or more of the arrays’ elements.

MongoDB takes 1 GB of RAM for every 100,000 assets. If the system has to start swapping memory to disk, this will have a significant performance impact and should be avoided.

MongoDB begins on port 27017 by default. However, you can access it via a web browser at a port that is 1000 higher than the port where MongoDB is started. So, if you go to http://localhost:28017 in your browser, you’ll see the MongoDB web interface.

To connect to your local MongoDB instance from a Container, you must first allow the Docker bridge gateway to accept connections. Simply add the relevant gateway IP to the bindIp section of the network interface section of the MongoDB config file /etc/mongod. conf.

MongoDB Atlas, the cloud-hosted MongoDB service alternative, has two fully-managed backup methods:

  1. Cloud Backups use the deployment’s cloud service provider’s native snapshot functionality to provide extensive backup alternatives. Cloud Backups include
    > On-demand snapshots, which let you take a snapshot of your deployment at any time; and
    > Continuous Cloud Backups, which let you plan recurrent backups.
  2. Legacy Backups (Discontinued), which take incremental backups of your deployment’s data.

Change your password and personal information. To update the password and custom data, use the db.updateUser() function.

Switch to the local database and execute db. collection. stats() against the oplog to see the current size. stats() returns the oplog size as maxSize in the rs collection.

MongoDB begins on port 27017 by default. However, you can access it via a web browser at a port that is 1000 higher than the port where MongoDB is started. So, if you go to http://localhost:28017 in your browser, you’ll see the MongoDB web interface.

Pass an empty document () to erase all documents in a collection. Set to true to limit the deletion to only one document. Remove all documents that fit the deletion criterion without using the default value of false.

Django can be linked to MongoDB in three ways:

  • PyMongo: PyMongo is the standard driver for interacting with MongoDB in Django. It’s the only technique to use MongoDB with Python that’s official and recommended. All database actions, such as search, remove, update, and insert, are supported by PyMongo. PyMongo is available on PyPI so that you can install it fast with the pip command.
  • MongoEngine: A Python Object-Document-Mapper, MongoEngine is a Python Object-Document-Mapper. In relational databases, it’s analogous to Object-Relational-Mapper. ManageEngine provides a simple declarative API to understand and utilize. 
  • Django: If you’re currently utilizing a relational database such as SQL and wish to switch to MongoDB, Django can help. Django transpires all SQL queries to MongoDB syntax queries without modifying the Django ORM.

The structure and contents of your data are defined by a schema, which is a JSON object. Realm’s BSON schemas, which extend the JSON Schema standard, can be used to design your app’s data model and validate documents as they’re produced, modified, or destroyed.

The headerline argument of the mongoimport command can be used to import CSV files into a collection. The headerline parameter informs the mongoimport command that the first line contains field names rather than data and should not be imported as a document.

  • Install MongoDB first. Dependencies on Debian
  • Set up MongoDB 
  • Implementing MongoDB

Run the mongo command from your server prompt to launch the MongoDB shell. The mongo command, by default, launches a shell linked to a locally installed MongoDB instance on port 27017. Try running mongo without any additional parameters: mongo.

The renameCollection() method in MongoDB can be used to rename or change the name of an existing collection. The collection has a new name. If true, mongod will drop the renameCollection target that was previously used to rename the collection. False is the default setting.

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