Oracle NoSQL Database Interview Questions and Answers for 7 years experience

1. What is Oracle NoSQL Database? What are its key features and benefits?

   • Answer: Oracle NoSQL Database is a distributed, scalable, key-value NoSQL database. Its key features include high availability, scalability, performance, and ease of use. Benefits include handling large volumes of unstructured data, faster query response times compared to relational databases for specific use cases, and improved application performance for high-throughput applications.

2. Explain the different data models supported by Oracle NoSQL Database.

   • Answer: Oracle NoSQL Database primarily supports the key-value data model. This means data is stored and retrieved using a unique key. While it doesn't directly support document or graph models like some other NoSQL databases, you can effectively represent structured data within the key-value pairs using JSON or other formats.

3. Describe the architecture of Oracle NoSQL Database.

   • Answer: Oracle NoSQL Database is a distributed database, meaning data is spread across multiple servers. It utilizes a distributed architecture with storage nodes and a coordination service for managing data distribution and consistency. This architecture enables high availability and scalability.

4. How does data replication work in Oracle NoSQL Database?

   • Answer: Oracle NoSQL Database uses configurable replication to ensure data durability and high availability. Data is replicated across multiple storage nodes, typically providing multiple copies. The replication strategy (synchronous or asynchronous) determines the trade-off between consistency and performance. Synchronous replication guarantees data consistency but can be slower, while asynchronous replication prioritizes speed but may have slight lag in consistency.

5. Explain the concept of consistent hashing in Oracle NoSQL Database.

   • Answer: Consistent hashing is a technique used to distribute data across storage nodes in a way that minimizes data movement when nodes are added or removed. It ensures that only a small portion of data needs to be re-distributed upon changes to the cluster, leading to better scalability and performance.

6. How do you handle data consistency in Oracle NoSQL Database?

   • Answer: Data consistency is managed through replication and configuration choices. The choice of synchronous or asynchronous replication significantly impacts consistency. Transactions can also be implemented to guarantee atomicity and consistency for specific operations, though they may have performance implications.

7. What are the different ways to access Oracle NoSQL Database?

   • Answer: Oracle NoSQL Database provides various APIs for accessing data, including Java, Python, C++, and RESTful interfaces. These APIs allow developers to integrate the database into their applications.

8. Explain the use of indexes in Oracle NoSQL Database.

   • Answer: Indexes significantly improve query performance by providing faster lookups for specific data. Oracle NoSQL Database supports secondary indexes, allowing you to create indexes on attributes other than the primary key. Properly chosen indexes are critical for optimization.

9. How do you perform schema management in Oracle NoSQL Database?

   • Answer: Oracle NoSQL Database is schema-less, meaning you don't need to define a fixed schema upfront. However, you can leverage data structures like JSON to maintain a logical schema within your data. Proper data modeling and consistent data structure use are essential for managing data effectively.

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