Top 100 NoSQL Interview Questions for 5+ Years of Experience

Basic NoSQL Questions

1. What are NoSQL databases, and how do they differ from relational databases?
2. What are the types of NoSQL databases? Explain each type.
3. What are the main advantages of using NoSQL over SQL?
4. Explain the concept of schema-less design in NoSQL databases.
5. What is CAP Theorem? How does it apply to NoSQL databases?
6. What is the difference between horizontal and vertical scaling in NoSQL?
7. What is eventual consistency, and how is it different from strong consistency?
8. What is sharding in NoSQL databases?
9. What are document stores? Give examples of NoSQL document databases.
10. What are key-value stores? Provide examples of NoSQL key-value databases.

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Intermediate NoSQL Questions

1. Explain column-family stores. How do they differ from relational databases?
2. What is data modeling in NoSQL databases?
3. What are the main differences between Cassandra and MongoDB?
4. What is MapReduce? How is it used in NoSQL databases?
5. How would you design a database schema for an e-commerce application in MongoDB or Cassandra?
6. Explain the concept of primary key and secondary indexes in NoSQL.
7. What is denormalization in NoSQL, and why is it often used?
8. How do you handle transactions in NoSQL databases?
9. Explain event sourcing and its usage in NoSQL databases.
10. What is data replication in NoSQL databases, and how does it work?

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Advanced NoSQL Questions

1. How does MongoDB handle distributed data?
2. What is the concept of tunable consistency in Cassandra?
3. How would you scale Cassandra or MongoDB for a high-traffic application?
4. What is the difference between strong consistency and eventual consistency in NoSQL databases?
5. Explain the concept of read-write consistency levels in Cassandra.
6. What are the advantages of using Redis as a NoSQL key-value store?
7. What are the best practices for indexing data in MongoDB?
8. What is geospatial indexing in MongoDB, and when would you use it?
9. What is denormalization in the context of NoSQL databases, and why is it necessary?
10. How does Cassandra handle data partitioning?

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Real-World Scenarios

1. How would you migrate data from a relational database to a NoSQL database like MongoDB?
2. What are the key considerations when designing a NoSQL database for real-time analytics?
3. How do you handle large datasets and query optimization in MongoDB or Cassandra?
4. Explain the differences between Cassandra and HBase in terms of scalability and performance.
5. How would you implement a high-availability system using Cassandra or Couchbase?
6. How would you design a highly available and fault-tolerant system using Redis?
7. How do you implement data consistency in event-driven systems using NoSQL?
8. How do you manage distributed data in a multi-region deployment?
9. Describe how you would ensure data integrity in a distributed NoSQL environment.
10. How would you handle data versioning in NoSQL databases?

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NoSQL Query-Based Questions

1. Write a query to find all documents in a MongoDB collection where a field contains a specific value.
2. How would you update a Cassandra column value with an atomic operation?
3. Write a query to retrieve documents in MongoDB sorted by a specific field in descending order.
4. How would you create an index on a specific field in Cassandra?
5. Write a query in Redis to increment a counter and return the current value.
6. How would you find the most frequent items in a Redis list?
7. How would you perform a range query in MongoDB for documents within a date range?
8. Write a query to find documents in MongoDB that contain a nested field with a specific value.
9. How would you retrieve a value from Redis using a hash?
10. How would you design a query to join two collections in MongoDB using aggregation pipeline?

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Performance and Optimization

1. How do you optimize queries in MongoDB or Cassandra for large datasets?
2. What are some techniques to improve the read performance in Cassandra?
3. How does MongoDB handle query execution plans? How can you optimize queries?
4. What are the advantages of in-memory databases like Redis?
5. How does Redis handle persistence? Explain its different persistence strategies.
6. What are write-heavy vs. read-heavy operations in Cassandra?
7. How do you handle indexing in NoSQL databases for performance optimization?
8. What are the challenges of scaling a NoSQL database for billions of records?
9. How do you monitor performance in Cassandra or MongoDB?
10. How would you optimize Redis for use as a session store in a high-traffic application?

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Data Integrity and Security

1. What are the security features in MongoDB, such as authentication and authorization?
2. How does Cassandra provide data integrity in a distributed system?
3. How would you ensure data privacy in a NoSQL database?
4. What are access control mechanisms in MongoDB?
5. How do you handle role-based access control (RBAC) in NoSQL databases?
6. How would you prevent data corruption in a distributed NoSQL environment?
7. How do you implement encryption at rest in MongoDB or Cassandra?
8. What are the challenges of ensuring data consistency in a multi-master NoSQL database?
9. Explain how data replication works in Cassandra and its impact on data consistency.
10. What is rate-limiting in Redis, and how can it be implemented securely?

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Advanced NoSQL Concepts

1. What is Tunable Consistency in Cassandra? Explain its impact on read and write operations.
2. How does Cassandra achieve high availability and fault tolerance?
3. Explain MongoDB’s replica sets and how they provide high availability.
4. What is data consistency in Cassandra? How do you ensure consistency during network partitions?
5. How does Couchbase handle distributed caching and data replication?
6. How would you implement eventual consistency in a NoSQL database?
7. What are the trade-offs of using eventual consistency in distributed databases?
8. How would you implement geo-spatial data indexing in MongoDB or Cassandra?
9. What is column-family design in Cassandra and how do you design it for performance?
10. Explain graph databases (e.g., Neo4j) and their use cases.

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Real-World Scenarios and Troubleshooting

1. How would you handle a partitioned NoSQL database?
2. What is the impact of network latency on the performance of Cassandra or MongoDB?
3. How do you handle data loss in NoSQL databases?
4. Explain a situation where you had to resolve data inconsistency issues in a distributed NoSQL system.
5. How would you recover from a replica failure in MongoDB or Cassandra?
6. How do you handle data migration between NoSQL and SQL databases?
7. How would you scale MongoDB horizontally to accommodate growing data?
8. How do you handle data integrity issues in a Cassandra cluster?
9. What strategies would you use for shard key selection in Cassandra?
10. How do you handle soft deletes in NoSQL databases?

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Best Practices

1. What are the best practices for data modeling in NoSQL databases?
2. How do you maintain data consistency across multiple NoSQL databases?
3. What is the best way to structure documents in MongoDB for optimal performance?
4. How do you ensure reliable replication in NoSQL systems?
5. What are the best practices for indexing in Cassandra or MongoDB?
6. How would you secure a Cassandra or MongoDB cluster in a cloud environment?
7. What strategies would you use for multi-region deployment in NoSQL databases?
8. How do you implement data archiving in **No

SQL databases**?

1. What are some common mistakes developers make when using NoSQL databases?
2. How do you design a disaster recovery plan for a NoSQL database?

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