NoSQL Interview Questions and Answers
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Best NoSQL Interview Questions and Answers
These top 30 NoSQL Interview Questions and Answers will assist aspirants for sure to clear the NoSQL interview with confidence. Level up your career in the NoSQL with our top 30 NoSQL interview questions and answers. In this one-stop resource we have covered almost all the topics of NoSQL so that you can crack easy, medium or difficult level NoSQL interview. Highly experienced and professional NoSQL experts are in huge demand today as NoSQL makes it simpler to process all structured, unstructured and semi-structured data. So aspirants can make use of our top 30 NoSQL interview questions and answers to crack the interviews.
Our top 30 NoSQL interview questions and answers are suitable for both freshers and experienced professionals to boost up their career. We wish you all success in your career search. All these questions are prepared in guidance with the top recruiters in the industry and so aspirants can confidently brush up their NoSQL skills with our top 30 NoSQL interview questions and answers. Let’s crack the interview together and achieve success.
NoSQL can be defined as the following:
- NoSQL is nothing but “Not Only SQL” which supports all SQL like query languages that are utilized in a relational database.
- NoSQL provides efficient techniques to easily store and retrieve data that are used apart from tubular relations utilized in the relational database.
NoSQL database are of different types and they are listed as below:
- Key Value Store
- Document Store
- Column Store
- Graph Databases
Some of the key features or highlights of NoSQL database are as follows:
- It is Schema Agnostic through which any data can be stored without the need for upfront schema design
- It supports auto-sharding and it is highly elastic as it allows the users to automatically share the workload to any number of servers
- It is highly distributable and so it makes use of a cluster of servers to store a single huge database
- It is highly scalable which ensures NoSQL database to support any volume of data and highly complex cloud applications
- It supports integrated caching through which the data that are cached will be transparent and all the application developers and operation team can view it at ease
Every data present in a database will consist of an indexed key and a value. Each key can represent one or more values. This type of NoSQL database ensure maximum database and it can be easily scaled as per the business needs.
The data record is nothing but a JSON or XML representation of a specific key value pair and every record can comprise several set of fields. Both document store database and key value store database are identical except the key in document store database represents or is associated with a document.
Every data that is stored in cells are grouped as columns of data and not as rows of data where all columns can be gathered in the form column families. Each row may contain one or several data records which can be indexed easily by a partition key.
Graph database is one of the special types of NoSQL database where graphical representations are highly used. The main aim of graph database is to store valuable relationships between specific nodes.
SQL Database | NoSQL Database |
It performs well with the relational database system | It performs well with the distributed database system |
It is vertically scalable | It is horizontally scalable |
The systems that come under SQL database is fixed and does not support flexibility | In NoSQL database, all the systems are dynamic and it is completely flexible |
It does not support hierarchical data storage | It supports hierarchical data storage |
Queries of any complexity can be handled | It cannot handle highly complex queries |
NoSQL Database | Relational Database Management System or RDBMS |
NoSQL does not follow any data pattern or data format | RDBMS it highly organized and structured |
NoSQL database is highly scalable | RDBMS is less scalable |
It is limited and ensures several restrictions in terms of query | As it is a structured query language it supports any form of queries |
NoSQL database uses key value pair, documents and column for storage | RDBMS makes use of table to store values and relationships |
Some of the advantages of NoSQL database are as follows:
- It can be used to store a huge quantity of structured, unstructured and semi-structured data
- It is highly compatible with quick iteration, agile sprint and regular code pushes
- It is one of the easy to use object oriented programming systems
- It is one of the scale-out and monolithic architectures which is highly affordable and efficient
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There are a few disadvantages available with NoSQL database and they are as follows:
- As this is a new database storage system in the market, there are several other database system already in use
- It does not ensure round the clock support rather than other database system
- As it a new technology, it does not support any old commands
The main advantages of graph database are as follows:
- Graph database is highly preferred to implement successful networking applications
- It can also support any of the object-oriented system with high efficiency
Some of the cons that are associated with the graph database are as follows:
- Graph database is highly not recommended for network partitioning as it involves huge interconnectedness among the various nodes available
- It can be easily and efficiently scaled as per business needs
Distributed key value databases that are designed to ensure highly scalable and reliable data are known as NoSQL database management system. There is several data storage present along with various configurable sets which can be defined as the storage nodes in which data are stored in the form of key value pairs. It ensures several methodologies to store and retrieve data in the form just different from tubular method which is utilized in relational database.
The process of retrieving in NoSQL database is handled effectively with the help of Oracle database external table functions and so it is highly considerable to execute some of the queries from the Oracle database and extract or retrieve data records from the NoSQL database at ease.
Polyglot programming was first established by Neal Ford in the year 2006 with an aim to create applications with a mix up of various programming languages to underline the fact that different programming languages are used in real-time to handle various complexities.
Every application comes with different complexities and each complex problem can be resolved and made perfect with a particular language and it is not possible to resolve or handle all the complexities within a single language. For instance, let’s take an e-commerce store where the functionality of cart is totally different from searching for a product and so both requires different language to make it effective, this is the main motive or objective of “Polyglot Persistence” too.
Replication node is the type of node that manages the data that are stored in the NoSQL database and it is also known as the memory consumer. The performance is calculation with the help of the java heap and the cache size that are found in the replication node. And, these two factors are calculated by NoSQL by means of memory that is available to a specific storage node where the specification for the memory of the storage node is highly required. If the storage node has more than one replication node, then the memory will be evenly scattered among the various replication node present.
In the year 2000, Eric Brewer discovered the CAP theorem which provides three main benefits to the NoSQL database management system and they are as follows:
Consistency – Through this benefit, every node can view the same data at a single point of time.
Availability – Every request will get an instant response whether it will become successful or not.
Partition Tolerance – This benefit is actually highly crucial as it will continue the work even if some of the practices or in error or if it is not working.
This is one of the most awaited characteristics which stood as an essential preference by most of the Analysts, Developers and Big Data Architects. The main function of “Tunable consistency” is that is synchronizes and keeps all the data rows on their respective replicas up to date. This consistency level can be opted by the users as per their preference and requirement. There are two types of consistencies present in Cassandra namely – Strong consistency and Eventual consistency.
Once all the service logics in a system are executed them the system will be moved to a consistent state which is denoted as the eventual consistency in NoSQL. This concept is highly used in distributed system to achieve maximum availability. In case a data item is not updated with any recent values, then the previously updated value will be displayed as the result. Nowadays, most of the present applications are developed in accordance with the eventual consistency feature of NoSQL database.
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BASE and RDMS of the NoSQL terms can also be defined as the ACID properties.
Few examples of NoSQL database are as follows:
- MongoDB
- Cassandra
- CouchDB
- HBASE
MongoDB and Cassandra are some of the NoSQL databases that support eventual consistency in some of their configuration goals.
Because of the scalable document structure and highly flexible nature of MongoDB, it is highly recommended than SQL database.
Cassandra is simply an open-source and free to use distributed NoSQL database management system by Apache which is highly utilized to handle and maintain huge volumes of data without any single point of failure. This big data model ensuring high availability and scalability was generally developed by Facebook. Among the several different NoSQL database management system, Cassandra comes under key-value store and column-oriented database.
The leading NoSQL database and a document oriented database that ensures maximum performance, availability and instant scalability is known as MongoDB.
MongoDB is recommended to be the best NoSQL database because of the following highlights:
- Document Oriented
- Rich Query language
- High Performance
- Highly Available
- Easily Scalable
No, MongoDB by default does not support the relationship of primary key and foreign key.
By embedding one of the documents inside the other document, it is possible to achieve primary key and foreign relationship in MongoDB.
NoSQL is stuffed with maximum benefits such that maximum organizations today prefer to use NoSQL but as it is new, organizations should take pre-cautionary steps to make use of it effectively. It is not flexible and as mature as SQL and MySQL and so we will have to consider many prerequisites before using this. In case your project does not come under any of the following like Yahoo, Facebook, Google, and Wikipedia then you should consider MySQL instead of NoSQL to enjoy better performance. Apart from finding a certified NoSQL professional, the process like performance reporting, migration and analytics are also complex.
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