Let's talk about several methods to clear the MySQL cache

MySQL Cache Clearing: How to Release MySQL’s Memory Resources

MySQL is a very widely used database. As the amount of data continues to increase and the amount of access continues to increase, the cache may be occupied. Too much space affects server performance. Therefore, clearing the MySQL cache in this case can significantly improve the efficiency of MySQL running on the server. This article will introduce you to several methods to clear the MySQL cache for your reference.

1. Clear key_buffer cache

Key_buffer is a cache of the MyISAM storage engine. It is mainly used to cache MyISAM commonly used index files, which can greatly improve query efficiency. If your application has a lot of write operations or the index file is too large, the cache usage of key_buffer may be high. You can clear the key_buffer cache through the following command:

FLUSH TABLES WITH READ LOCK;
FLUSH QUERY CACHE;
RESET QUERY CACHE;
RESET MASTER;

2. Clear query_cache cache

In addition to the key_buffer cache, MySQL has another caching method query_cache, which can cache SELECT query statement and store its results in the cache. The user can obtain data from the cache when querying again, which greatly improves query efficiency. However, this cache is not suitable for large-scale write operations. You can clear the query_cache cache with the following command:

FLUSH QUERY CACHE;

3. Clear innodb_buffer_pool cache

InnoDB storage engine often uses the innodb_buffer_pool cache to cache recently used data and indexes to make them faster to handle subsequent query requests. However, if your data volume is too large and the cache takes up a lot, it may affect the operating efficiency of MySQL. You can clear the innodb_buffer_pool cache through the following command:

SET GLOBAL innodb_buffer_pool_size=0;
SET GLOBAL innodb_buffer_pool_size=<<memory-size>>;

Among them, <> ; Set the innodb_buffer_pool cache size you need to set, for example 256M.

4. Restart the MySQL service

If MySQL still takes up a lot of memory resources after clearing the cache using the above method, you can try restarting the MySQL service. Restarting MySQL allows MySQL to clear all occupancies in memory first, ensuring that the cache occupies less space. You can restart the MySQL service through the following command:

service mysql restart

Summary

When using the MySQL database, clearing the cache can release MySQL's memory resources and ensure the normal operation of MySQL. Whether it is clearing the key_buffer cache, clearing the query_cache cache, clearing the innodb_buffer_pool cache, or restarting the MySQL service, you need to make a choice based on the actual situation to ensure the normal operation of MySQL on the server and the error-free execution of related operations.

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