How does Redis maintain database consistency?

There are several methods to maintain database consistency in Redis.

1. Transaction: Redis supports transaction operations, allowing multiple operations to be encapsulated into a single transaction using the MULTI and EXEC commands, which are then executed together. During the transaction, other clients are prevented from modifying the data in the transaction, ensuring data consistency.
2. Lock: Use the SETNX command in Redis to implement distributed locking. Before carrying out a certain operation, try setting a specific key to a locked state. If the setting is successful, proceed with the operation. If not, it means that another client is currently executing the operation and you need to wait. By using locking and unlocking operations, you can ensure that only one client at a time is modifying the same data, thus maintaining consistency.
3. Data Replication: Redis supports master-slave replication, which allows data from the master node to be copied to multiple slave nodes. Changes to the data on the master node will be synchronized to the slave nodes to maintain data consistency. In the event of the master node going down, read and write operations can still be performed using the data from the slave nodes, ensuring high availability and consistency of services.
4. Publish/Subscribe: Redis offers a feature for publish/subscribe, which allows data changes to be broadcasted to subscribers in the form of messages. Subscribers can receive these messages to promptly update their data, ensuring consistency.
5. Election: In a distributed environment, Redis atomic operations can be used to implement an election algorithm to elect a primary node for data read and write operations, with other nodes serving as backup nodes. In the event of a primary node failure, a new primary node can be elected using the election algorithm from one of the backup nodes to maintain data consistency.

The above methods can be selected based on specific application scenarios and requirements, or a combination of multiple methods can be used to ensure the consistency of the Redis database.