MYSQL optimization address (reproduced) http://blog.csdn.net/wenniuwuren

MySQL Help Manual
7.2.1. EXPLAIN syntax (to obtain SELECT related information)
7.2.12. How MySQL optimizes ORDER BY

"High Performance MySQL" (Second Edition) Chinese Version
P463 (pdf.487) Appendix B

"MySQL Performance Tuning and Architecture Design"

MySQL ORDER BY Implementation Analysis
http://isky000.com/database/mysql_order_by_implement

Mysql Execution Plan
http://www.xifenfei.com/954.html

MySQL Execution Plan Interpretation
http://wenku.baidu.com/ view/41846439376baf1ffc4fad4f.html

Mysql Explain detailed explanation
http://www.cnitblog.com/aliyiyi08/archive/2008/09/09/48878.html Mysql

EXPLAIN statement extended option learning experience
http://hi.baidu.com/dearhwj /blog/item/03badf17641a28094a90a78d.html

Show Warnings

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List of MySQL Index Types Make MySQL Run Efficiently
http://database.51cto.com/art/200910/156685.htm

Using filesort in Mysql execution plan
"indicates which index Mysql can use to find rows in this table"
http://www.taobaodba.com/html/ 235_mysql_using_filesort.html

2.order by b, if column b is not in the index, no matter whether the b value is the same or not, Using filesort will always appear.

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What does Using filesort mean in MySQL?
"Any sort that cannot be done by index is called filesort"
http://iceskysl.1sters.com/?p=638

using filesort in mysql explain
"only if possible If so, modify the sorting conditions of the query"
http://blog.csdn.net/wdwbw/article/details/5256064

Mysql EXPLAIN shows using filesort
"The result saw one from the company yesterday"
http://www.ccvita.com/169 .html (maybe this is the source)

The multi-column index is built with a B-tree structure when it is established, so when building the index, the index in order of ID is first established, and the FID is established in order in the case of the same ID. Finally, if the FID is the same, the index in the order of INVERSE_DATE is established, if the number of columns is more, and so on.

To optimize this sql, you should create another index IDX (ID, INVERSE_DATE) for it, so that the speed of using filesort is eliminated and the speed is much faster.

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mysql optimizes Using filesort
"and uses the room_number column index"
http://www.askwan.com/post/151/

MySQL index optimizes Using filesort
"The page comes out with a click"
http://www.leakon .com/archives/332