About MySQL Federated index

CREATE TABLE ' uniontest ' (  ' id ' int (one) not null auto_increment,  ' menuname ' varchar () DEFAULT NULL,  ' url ' V Archar (+) DEFAULT NULL,  PRIMARY key (' id '),  UNIQUE key ' U_index ' (' menuname ', ' url ')) Engine=innodb auto_ Increment=5 DEFAULT Charset=utf8

Set up the database first, setting the Menuname and URL as the federated index

A few things to note:

1. When inserting data, MySQL has checked the uniqueness of menuname and URL two columns at the same time.

Such as:

INSERT into Uniontest (' menuname ', ' url ') VALUES (' Order Management ', ' aaa.php ') success

INSERT into Uniontest (' menuname ', ' url ') VALUES (' Order Management ', ' bbb.php ') success

INSERT into Uniontest (' menuname ', ' url ') VALUES (' Order Management 2 ', ' aaa.php ') success

INSERT into Uniontest (' menuname ', ' url ') VALUES (' Order Management ', ' aaa.php ') failed

2, at the time of inquiry

Explain SELECT * from uniontest where menuname = ' order management ' used to index

Explain SELECT * from uniontest WHERE menuname = ' order management ' and URL = ' aaa.php '; Use to Index

Explain SELECT * from uniontest WHERE url = ' aaa.php '; The index is not used

Followed the principle of the leftmost priority of the Federated index.

About MySQL Federated index