Home > Database > Mysql Tutorial > body text

Select * 一定不走索引是否正确?

WBOY
Release: 2016-06-07 17:39:27
Original
1722 people have browsed it

Select * 一定不走索引是否正确? 走索引指的是:SQL语句的执行计划用到了1、聚集索引查找 2、索引查找 ,并且查询语句中需要有where子句 根据where子句的过滤条件,去聚集索引或非聚集索引那里查找记录 一张表只有一列的情况: 聚集索引 t1 ( id INT ) CIX_

Select * 一定不走索引是否正确?

走索引指的是:SQL语句的执行计划用到了1、聚集索引查找  2、索引查找  ,,并且查询语句中需要有where子句

根据where子句的过滤条件,去聚集索引或非聚集索引那里查找记录

一张表只有一列的情况:

聚集索引

t1 ( id INT ) CIX_T1 .(ID ASC) .( ) .

Related labels:
source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn:Public welfare online PHP training,Help PHP learners grow quickly!