Which of the following is the most important consideration while designing the schema for NoSQL?
Data in MongoDB has a flexible schema.documents in the same collection. They do not need to have the same set of fields or structure Common fields in a collection’s documents may hold different types of data. Show
Data Model DesignMongoDB provides two types of data models: — Embedded data model and Normalized data model. Based on the requirement, you can use either of the models while preparing your document. Embedded Data ModelIn this model, you can have (embed) all the related data in a single document, it is also known as de-normalized data model. For example, assume we are getting the details of employees in three different documents namely, Personal_details, Contact and, Address, you can embed all the three documents in a single one as shown below − { _id: , Emp_ID: "10025AE336" Personal_details:{ First_Name: "Radhika", Last_Name: "Sharma", Date_Of_Birth: "1995-09-26" }, Contact: { e-mail: "", phone: "9848022338" }, Address: { city: "Hyderabad", Area: "Madapur", State: "Telangana" } }Normalized Data ModelIn this model, you can refer the sub documents in the original document, using references. For example, you can re-write the above document in the normalized model as: Employee: { _id:Personal_details: { _id:Contact: { _id:Address: { _id:Considerations while designing Schema in MongoDB
ExampleSuppose a client needs a database design for his blog/website and see the differences between RDBMS and MongoDB schema design. Website has the following requirements.
In RDBMS schema, design for above requirements will have minimum three tables. While in MongoDB schema, design will have one collection post and the following structure − So while showing the data, in RDBMS you need to join three tables and in MongoDB, data will be shown from one collection only. NoSQL databases have gained enormous popularity and a mass of advocates. MongoDB is the most popular NoSQL database with a continuously expanding user base at almost the same rate as other RDBs (Relational Databases). MongoDB is known to be the next-generation document storage system due to its high performance, flexibility, and scalability when working with large sets of distributed data. Below, we'll go over the most common MongoDB interview questions to help you prepare for your system design, NoSQL Databases, or MongoDB interview. We will start with the basics by simulating real-world interviews with recruiters and then gradually increase the complexity. Jump to:
What is MongoDB?MongoDB is an open-source document-oriented NoSQL database that was created in 2007 by Dwight Merriman, Eliot Horowitz, and Kevin Ryan. Rather than tables, columns, and rows, MongoDB is based on collections and JSON-like documents instead of databases. What are the advantages of MongoDB?MongoDB is known to be the best NoSQL database because of its following key features:
What are the different types of NoSQL databases?NoSQL stands for "Not Only SQL." NoSQL is a database that can handle all types of structured, large, and complex data. NoSQL database types include:
What are MongoDB documents and collections?A Document in the MongoDB database is an object that represents a single record, and it is analogous to a row in a SQL table. MongoDB document has a key/value structure. A Collection is a set of related documents; it acts as the equivalent of RDBs (relational database) tables. MongoDB database is simply a group of collections that hold a set of similar or partially similar documents. What syntax is used to create and drop a collection in MongoDB?db.createCollection(name,options) // create collection in MongoDB db.collection.drop() //drop collection in MongoDBHow do you perform Insertion or Creation operations in MongoDB?db.collection.insertOne({data}) // create single document at a time db.collection.insertMany({data}) // insert many documents at onceHow do you perform update operations in MongoDB?Syntax to update one document in MongoDB is: db.collection.updateOne({filter}, {update})Syntax to insert many documents MongoDB is: db.collection.updateMany({filter}, {update})How does MongoDB store data?MongoDB NoSQL database stores documents in BSON format, the binary encoded format of JSON. BSON offers different data types over JSON data. However, it uses more space as compared to JSON. List some of the data types supported by MongoDB.Some data types are:
Explain Namespace in MongoDB.The combination of a database name with a collection or an index name using the . separator is called a namespace. [database-name].[collection-or-index-name]Does MongoDB support primary-key, foreign-key relationships?By default, MongoDB doesn't support primary key-foreign key relationships. Every document in MongoDB contains an _id key field that uniquely identifies the document. However, this concept can be implemented by embedding one copy inside another. Explain different data models in MongoDB.MongoDB provides the following types of data models:
What is a Relational Database Management System?Data points that are related to one another are stored and accessible in a relational database. The relational model, an easy-to-understand method of representing data in tables, is the foundation of a relational database management system. What are the guidelines for designing a good database schema in MongoDB?Here are some general guidelines linked to schema design in a document-oriented database that highlights important considerations one should consider while modeling data relationships:
Explain Aggregation in MongoDB.In MongoDB, aggregation is a multi-stage data processing pipeline used to run a series of complex operations on a collection of documents. Each stage in the aggregation pipeline will receive input documents, transform them, and then forward the results as input to the next step down the pipeline until our goal is achieved. The stages in a pipeline can filter, sort, group, reshape and modify documents that pass through the pipeline. Data Aggregation use cases include:
List some of the aggregate stages of MongoDB.Some of the aggregate stages of MongoDB are:
Is there any need to create a database manually in MongoDB?MongoDB eliminates the need for manual database creation by automatically creating one whenever a value is first saved into a defined collection. Explain the importance of the dot notation.We use dot notation in MongoDB to retrieve the array elements and fields of an embedded document. Can we perform the SQL JOIN equivalent in MongoDB?Mongo is not a relational database; however, doing join is now possible with MongoDB 3.2+. The new $lookup aggregation operator works in the same way as a left outer join: { $lookup: { from: |