How to improve performance by caching MySQL query results

As the scale of applications continues to increase, the query performance of the MySQL database often becomes a problem, so how to improve performance by caching MySQL query results has become an important topic. This article will introduce some knowledge about MySQL cache and discuss some methods to improve MySQL query performance.

What is MySQL cache?

MySQL caching means that the MySQL database caches query results in memory so that data can be retrieved faster in future queries. MySQL caching can be implemented by storing the results in memory after the query is completed. The next time you query, if the queried table has not changed, the results can be returned directly from the cache without having to execute the query again. In this way, the time of loading data from disk and querying can be greatly reduced.

MySQL internal query cache

MySQL has an internal query cache mechanism for caching query results. This mechanism is optional and is enabled by default. Prior to MySQL 5.6, this cache was generally considered a good solution, but it had some limitations. First, the cache is limited in size, and caching query results is not very efficient for certain query patterns (such as the same query with different WHERE conditions). Second, if the data in a table is updated, the cache for that table will be cleared, which means that query caching is less efficient.

How to enable the built-in MySQL query cache?

To enable MySQL's built-in query cache, simply set the following value in the my.cnf file:

query_cache_type=1
query_cache_size=32M

Where, query_cache_type Indicates that query caching is enabled, 1 means enabled, 0 means disabled; query_cache_size means the memory size that can be used to cache query results.

In addition to enabling query caching inside MySQL, other methods can be used to cache query results.

Use Memcached to cache MySQL query results

Memcached is a high-performance distributed memory object caching system that provides caching services for many web applications. It can improve application performance by reducing the load on the database by storing data in memory. Considering the high performance of Memcached, the performance of MySQL can be improved by caching MySQL query results into Memcached.

How to use Memcached to cache MySQL query results?

First, install Memcached and start it. Second, in the application, use Memcached's client library to store the query results into Memcached. Finally, when the next query requires the same data, the application can retrieve the data from Memcached without having to query the database again.

Use Reds to cache MySQL query results

Reds is another high-performance caching system that uses Redis as the storage backend and provides an easy-to-use interface to facilitate applications Store data in Redis. Reds performs much better than MySQL's query cache because it uses memory-based storage, and it allows applications to flexibly choose between different caching tiers.

How to use Reds to cache MySQL query results?

Similar to Memcached, to use Reds to cache MySQL query results, you need to install and start Redis, and use the Reds client library to store and retrieve data. When the next query requires the same data, the application can retrieve the data from Redis without having to query the database again.

Use other caching tools

In addition to Memcached and Reds, you can also use other caching tools to cache MySQL query results. Some of these tools are better than MySQL's query cache in terms of performance, such as:

• Nginx cache
• Varnish cache
• Squid cache

By using any of these tools, you can cache MySQL query results into memory and get high-speed access from the cache.

Summary

By using the technology of caching MySQL query results, the performance of the application can be greatly improved. Query caching inside MySQL is a simple approach, but its performance may not be outstanding due to its limitations. Some external caching tools have certain advantages in performance. Using these tools to cache MySQL query results can greatly improve application performance and reduce database load.

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