What does the caching mechanism of mybatis include?

The caching mechanism of mybatis includes: 1. First-level cache and second-level cache; 2. Function; 3. Configuration and use; 4. Precautions; 5. Optimization suggestions; 6. Comparison with other frameworks; 7. Future development. Detailed introduction: 1. First-level cache and second-level cache. MyBatis's first-level cache is based on SqlSession, while the second-level cache is based on Mapper. The first-level cache is automatic and does not require special configuration, while the second-level cache requires manual operation. When enabled and configured, the first-level cache stores the results of query operations and so on.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

MyBatis is a popular Java persistence layer framework that provides a variety of caching mechanisms to optimize performance and improve data access efficiency. The caching mechanism of MyBatis is mainly divided into the following types:

1. First-level cache and second-level cache:

• The first-level cache of MyBatis is based on SqlSession , and the second-level cache is based on Mapper. The first-level cache is automatic and does not require special configuration, while the second-level cache needs to be manually enabled and configured.
• The first-level cache stores the results of query operations, while the second-level cache stores entity objects.
• The life cycle of the first-level cache is short-lived. When the SqlSession is closed or the transaction is committed, its cache will be cleared. The life cycle of the second-level cache is persistent and data can be shared between multiple SqlSession.

2. Function:

• The function of the first-level cache is to reduce the number of database accesses and improve data access efficiency. When performing a query operation, MyBatis will first check whether the data exists in the first-level cache. If it exists, the cached data will be returned directly. Otherwise, the data will be queried from the database and stored in the first-level cache.
• The function of the second-level cache is to provide cross-SqlSession data sharing function. In a distributed system, if multiple SqlSession access the same data, turning on the second-level cache can avoid repeated queries to the database and improve the overall performance of the system.

3. Configuration and use:

• The first-level cache is enabled by default and no special configuration is required. To use the second-level cache, you need to enable the global second-level cache in the MyBatis configuration file and configure the corresponding caching strategy in the Mapper interface or XML mapping file that needs to use the cache.
• MyBatis supports a variety of caching strategies, such as updating the cache after a read operation, updating the cache after a write operation, manually updating the cache, etc. You can choose an appropriate caching strategy based on actual needs.

4. Note:

• Using second-level cache may cause data consistency problems in some cases. Because multiple SqlSession may modify the same data at the same time, and the second-level cache shares data between multiple SqlSession, it may lead to data inconsistency. Therefore, concurrent modifications need to be handled carefully when using the second-level cache.
• In addition, the second-level cache may encounter cache consistency problems in distributed systems. If multiple nodes share the same cached data, you need to ensure that the cached data synchronization mechanism between nodes is correctly implemented to avoid data inconsistency.

5. Optimization suggestions:

• For the first-level cache, its size and life cycle can be appropriately controlled to avoid taking up too much memory. Or clear the cache frequently.
• For the second-level cache, you can choose the appropriate cache strategy and synchronization mechanism according to actual needs, and regularly clean up expired or invalid cache data to maintain the accuracy and effectiveness of the cache data.

6. Comparison with other frameworks:

• Compared with other persistence layer frameworks, MyBatis’ caching mechanism has high flexibility and configurability. Different caching strategies and synchronization mechanisms can be selected according to actual needs to adapt to different application scenarios and performance requirements.

7. Future development:

• With the continuous development of technology and the deepening of applications, MyBatis' caching mechanism may continue to be improved and improved. In the future, more advanced caching strategies and synchronization mechanisms may appear to meet more complex application needs and performance requirements.

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