This is an SQL statement they developed
- Select id, title, createdate from table name order by createdate asc limit 334570,10;
The person who asked this question meant reading the oldest news title and reading 10 records from 334570 rows of data.
The index information is as follows:
650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S3524241-0.jpg "alt =" "/>
The optimizer executes the following:
650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S3523517-1.jpg "alt =" "/>
This reminds me of an optimization case of the second High-Performance edition.
Let's take a look at the SQL Execution:
650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S3522151-2.jpg "alt =" "/>
This is after optimization:
650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S352F64-3.jpg "alt =" "/>
The specific reason is that I will not make a shift here. Please read the high-performance MySQL 2nd version. below is the description in the book:
650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S3524255-4.jpg "alt =" "/> 650) this. width = 650; "border =" 0 "src =" http://www.bkjia.com/uploads/allimg/131229/1S35251J-5.jpg "alt =" "/>
This article is from the "hechun's technical column" blog, please be sure to keep this source http://hcymysql.blog.51cto.com/5223301/1123388