Key-value store

Document store

Column-family store

Relational database

Strict ACID compliance

Vertical scaling only

Schema-based data model

Flexible schema

Not Only SQL

Document databases, key-value stores, column-oriented databases, and graph databases

Document databases, key-value stores, graph databases, and relational databases

Key-value stores, column-oriented databases, and graph databases

None of the above

When you need to store a large amount of data

When you need to store data that is not well-suited for the relational model

When you need a database that is scalable and fault-tolerant

All of the above

MongoDB

Cassandra

DynamoDB

All of the above

CouchDB

Cassandra

Neo4j

Redis

Transaction isolation

Data encryption

Data validation constraints

Backup and recovery

To log all user actions during a transaction

To provide a consistent state of the database after a system crash or unexpected shutdown

To monitor and analyze database performance over time

To automatically rollback transactions that fail to commit