How to keep redis cache consistent with database

It is crucial to maintain consistency between the Redis cache and database data. The following methods can achieve data consistency: 1. Update the cache when writing (immediately update the Redis cache); 2. Check the cache when writing (store the update in the queue, and the background process updates the Redis cache); 3. Separate reading and writing ( Use master-slave database replication to avoid write conflicts with the master database); 4. Update the cache regularly (background tasks are updated to the Redis cache synchronously); 5. Use an event-driven mechanism (receive database update notifications and update the Redis cache accordingly). Choosing the appropriate strategy depends on application needs and consistency requirements.

Redis cache and database data consistency

Question: How to maintain Redis cache and database data consistency consistency?

Answer:

It is crucial to maintain Redis cache and database data consistency to ensure that the application provides accurate and reliable data. The following are some methods to achieve data consistency:

1. Update cache when writing (Write-Through)

• The application performs writes in the database Immediately after the operation, the updates are applied to the Redis cache.
• This approach ensures that the Redis cache is always in sync with the database.

2. Check cache when writing (Write-Behind)

• After the application performs a write operation in the database, it stores the update in in the temporary queue.
• The background process retrieves updates from the queue and applies them to the Redis cache.
• This method allows immediate write operations, but may cause the Redis cache to briefly become out of sync with the database.

3. Read-Write Splitting

• Use master-slave database replication, where the master database is used for write operations, and Used for read operations from the database.
• Redis cache only reads data from the slave database, thus avoiding write conflicts with the master database.

4. Regularly update the cache

• Periodically perform background tasks to synchronize updates from the database to the Redis cache.
• This approach is useful when the cache is updated less frequently or when the application tolerates short-term inconsistencies.

5. Use event-driven mechanism

• Use database event triggers or message queues to notify the Redis cache about database updates.
• The Redis cache receives notifications and updates its content accordingly.

Choose the appropriate strategy

Choosing the best strategy depends on the specific needs and consistency requirements of your application:

• High consistency: Update on write or read and write separation
• High performance: Check on write or regular update
• Fault tolerance :Event-driven mechanism

In addition, the following tips can help improve data consistency:

• Use versioning to track data in the cache.
• Regularly clean up expired data to prevent cache expansion.
• Monitor cache performance and data consistency to identify and resolve issues.

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