What is the difference between MyBatis cache and Redis cache?

The differences between MyBatis cache and Redis cache are as follows:

1. Storage location: MyBatis cache is stored in memory, while Redis cache is stored in the Redis server.
2. Scope: MyBatis cache is application-level cache, only valid for all sessions of the current application; while Redis cache is cross-application level cache, can be shared by multiple applications.
3. Cache granularity: MyBatis cache is based on object granularity, storing query result objects; while Redis cache can store any type of data, providing more flexible support for caching various data structures.
4. Cache policy: MyBatis default uses the LRU (Least Recently Used) policy and can also be configured with custom cache policies; Redis cache supports multiple cache policies such as LRU, LFU (Least Frequently Used), TTL (Time To Live), etc.
5. Expiration Mechanism: MyBatis cache uses a timestamp and dependency-based expiration mechanism, automatically refreshing the cache when data is updated; Redis cache can set expiration time or manually delete cached data.
6. Data synchronization: MyBatis cache automatically updates when database data changes, while Redis cache requires manual maintenance of data synchronization.
7. Scalability: MyBatis cache is a part of the MyBatis framework and closely related to the database access logic; whereas Redis cache is a third-party cache server independent of the application, which can be shared by multiple applications, making it more flexible and scalable.

In conclusion, MyBatis cache is suitable for in-memory caching for single applications and is best for small-scale applications; on the other hand, Redis cache is suitable for sharing across applications and meeting the caching needs of large-scale applications, providing greater flexibility and scalability.