优化快速精准解决MySQL查询慢问题（mysql查询慢查询）
Big data has become an indispensable part of modern life. When dealing with a large amount of data, MySQL is often used. In many situations, MySQL query speed is a concern, and the purpose of taking optimizations is to quickly and accurately solve query slow problems.
The optimization of query speed, generally speaking, is to reduce the demand for query resources. Specific operation can be divided into several stages:
1. Improve the efficiency of the query statement:
The most basic measure to optimize queries is to check whether the syntax of SQL statements are correct. Make sure to end the sentence with a semicolon. And also check whether to add necessary indexes and primary keys. They will be necessary when the query involves multiple tables. In addition, when using joins, be sure to select the most efficient type of join.
2. Separate single-table reading queries and multi-table join queries:
When the query needs to involve multiple tables, try to separate single table reading queries into multiple front-end, asynchronous places, and multi-table join queries to the background, thus, avoiding large data traffic, and also improving query efficiency.
3. Use properly function, trigger and stored procedure:
I’m sure this you have heard a lot of using stored procedure, functions and triggers. Such commands play an important role in optimizing query speed. Using stored procedure, you can pre-compile SQL statements. When it comes to functions and triggers, the can help filter unnecessary data and access data more quickly and efficiently.
4. Create partial index:
If necessary, we can create partial indexes, which can help reduce index scan and increase query speed in most cases. For example, on a large table, we can specify index fields according to query conditions such as CREATE INDEX part_index ON tablename(fieldname).
5. Increase the query cache:
The MySQL query cache can optimize the query speed. We can set the query_cache_size and try to increase it in the configuration file, thus increasing the probability that the same query can get the cached query results.
In general, when it comes to the optimization of query speed, there are many methods, as long as we optimize in an all-round way and carry out targeted sizing, it can greatly improve the query speed.
