What do you know about NoSQL databases? Which ones have you worked with?

NoSQL databases are non-relational data storage systems characterized by flexible schemas, scalability, and high performance when working with large volumes of data. The main types of NoSQL databases:

• Document-oriented (e.g., MongoDB) — store data in JSON-like documents.
• Key-value (e.g., Redis) — simple structure for fast access by key.
• Column-oriented (e.g., Cassandra) — optimized for analytics and large data volumes.
• Graph (e.g., Neo4j) — for storing and analyzing graphs and relationships.

In my practice, I have worked with MongoDB and Redis. I used MongoDB for storing complex structured data with a dynamic schema, and Redis for caching and implementing message queues due to its high speed.