MongoDB 2026 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. 2026
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.
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. Practice with the free MongoDB practice test on PracticeTestGeeks (9 questions with answer explanations).
Area is a mobile-to-cloud synchronization solution faster and more scalable than SQLite. Area 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 area may be used to create apps for mobile, web, desktop, and IoT. Area 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. Area provides open-source SDKs for major programming languages, frameworks, and platforms. The following are some of the benefits of using Area:
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.
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 using 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 | MongoDB |
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There are two server editions of MongoDB: Community and Enterprise. The instructions to install it on Windows are as follows:
alias mongod="/c/Program files/MongoDB/Server/4.0/bin/mongod.exe"
alias mongo="/c/Program Files/MongoDB/Server/4.0/bin/mongo.exe"
mongo --version
Numbers in brackets link to the official sources listed under Sources & last verified. Dates that have passed are removed automatically.
| Item | Detail | Source · Verified |
|---|---|---|
| Number of questions (Associate Database Administrator) | 75 questions[1] | MongoDB, Inc. · Oct 31, 2026 |
| Number of questions (Associate Developer) | 53 questions[2] | MongoDB, Inc. · Oct 31, 2026 |
| Time limit (Associate Database Administrator) | 90 minutes[1] | MongoDB, Inc. · Oct 31, 2026 |
| Time limit (Associate Developer) | 75 minutes[2] | MongoDB, Inc. · Oct 31, 2026 |
| Passing score | Pass/fail (percentage not published)[3] | 10geneducation.zendesk.com · Oct 31, 2026 |
| Exam fee (Associate Database Administrator) | $150 USD[1] | MongoDB, Inc. · Oct 31, 2026 |
| Exam fee (Associate Developer) | $150 USD[2] | MongoDB, Inc. · Oct 31, 2026 |
| Retake policy | 15-day cooling-off period[4] | 10geneducation.zendesk.com · Oct 31, 2026 |
| Delivery | Online proctored[5] | 10geneducation.zendesk.com · Oct 31, 2026 |
| Eligibility | At least 18 years old, valid government ID[6] | MongoDB, Inc. · Oct 31, 2026 |
| Score release | Immediate upon exam completion[7] | 10geneducation.zendesk.com · Oct 31, 2026 |
| Testing window | On-demand year-round[8] | 10geneducation.zendesk.com · Oct 31, 2026 |
Interactive MongoDB resources on PracticeTestGeeks, free to start:
According to MongoDB, Inc., “MongoDB Certification exams have a pass/fail grading system that is determined through statistical analysis performed by psychometricians. Candidates must meet a required percentage to pass an exam. MongoDB does not publish the required percentages for our certifications”[3]
Prepare for the MongoDB exam with our free practice test modules. Each quiz covers key topics to help you pass on your first try.
These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.
Question: What does the findOne() method return when no matching document is found?
Answer: B. null
Explanation:
The correct answer is null. When a query filter matches nothing, findOne() has no document to return, so it gives back null. That makes it easy to test with a simple check before you read fields from the result.
An empty object is wrong because it would look like a real document with no fields, and MongoDB does not invent one. Undefined is wrong because the driver returns an explicit null for a missing document. An empty array is wrong because arrays belong to find() results turned into a list, not to a method that returns a single document.
Rule to remember: methods that return one document give a document or null, and methods that return many give a cursor.
Question: What is the Atlas M0 free tier limitation regarding shared clusters?
Answer: A. Maximum 100 MB storage and limited connections/operations per second
Explanation:
The correct answer is the option describing small storage with limited connections and operations per second. The M0 free tier runs on shared resources, so MongoDB caps what a single free cluster can use. It suits learning and prototypes, not production.
The option with 5 GB and no connection limits is wrong because the free tier is restricted on both counts. The option saying it needs a paid subscription is wrong because the point of the tier is that it costs nothing. The option saying M0 cannot use replica sets is wrong because Atlas clusters are replica sets by design.
Rule to remember: free and shared tiers trade capacity for cost, so check the current limits in the Atlas documentation before relying on any specific figure.
Question: What is a partial index in MongoDB?
Answer: B. An index that only includes documents meeting a specified filter expression
Explanation:
The correct answer is an index that only includes documents meeting a specified filter expression. A partial index stores entries just for documents that satisfy the filter, so it is smaller and cheaper to maintain than a full index on the same field.
An incomplete index being built in the background is wrong because that describes an index build in progress, not a type of index. An index covering only part of a field's value is wrong because partial refers to which documents are indexed, not to slices of a value. A degraded index after hardware failure is wrong because it describes damage, not a feature.
Rule to remember: partial indexes narrow the set of documents, and a query can only use one if its filter is compatible with the index filter.
Start with the official exam page for the certification you have chosen, and note the listed format and the topics MongoDB describes. Decide whether you are aiming at the Associate Developer or the Associate Database Administrator exam, because the emphasis differs.
Next, take a practice set on a topic you already use daily, such as CRUD operations, to see how our question style reads. Then move to the areas that feel weaker. Developers will want aggregation, data modeling and indexing. Administrators should add replica sets, sharding, security and Atlas.
After every wrong answer, read the explanation, then reproduce the behaviour in a real shell or a free Atlas cluster. Running the command teaches more than rereading the answer. Keep a short list of mistakes and revisit it before the next session.
Close the plan by working through a mixed set under timed conditions that match your exam page. Our questions are written by us and are not real exam questions, so use them to find gaps, not to predict a result.
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:
The MongoDB community is reshaping industries and enabling 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:
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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.
Syntax:
db.Collection_Name.sort({filed_name:1 or -1})
The following are some critical points to know when using the MongoDB Sort() Method:
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> ] }
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)
Parameters:
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 reports more than 67,000 customers worldwide as of 2026 (source: mongodb.com/company). Exact current figures for MongoDB University registrations and total downloads are not independently verifiable and are omitted here rather than repeating outdated numbers.
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.
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 use 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 strong and detailed database management tool, so you’ll probably need approximately three weeks to get up to speed.
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:
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:
The structure and contents of your data are defined by a schema, which is a JSON object. Area’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.
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.
Try these questions from our free MongoDB practice tests. The correct answer and an explanation follow each question.
What is the recommended write concern for MongoDB transactions to ensure durability?
Answer: C. { w: 'majority' }
{ w: 'majority' } is the recommended write concern for transactions. It ensures the committed transaction has been written to a majority of replica set members, providing durability. Using w: 1 risks rollback if the primary fails before the secondary replicates the commit.
Which command enables sharding for a specific database in MongoDB?
Answer: B. sh.enableSharding('dbName')
sh.enableSharding('dbName') enables sharding at the database level, which is required before sharding individual collections. This is run via the mongos router. Then sh.shardCollection('dbName.collectionName', { shardKey: 1 }) shards a specific collection.
What is the role of the oplog in MongoDB replication?
Answer: B. A capped collection on the primary that records all write operations for secondaries to replicate
The oplog (operations log) is a special capped collection in the local database that records all write operations in an idempotent form. Secondary members tail the primary's oplog and replay operations to stay in sync with the primary.
What does MongoDB's TLS/SSL configuration protect?
Answer: B. Data in transit between clients and servers
TLS/SSL encrypts network communications between MongoDB clients, servers, and replica set members to prevent eavesdropping and tampering.
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