Percona 5.5如何定位未使用的索引
发布时间：2021-12-28 12:00:27 所属栏目：MySql教程 来源：互联网
导读：这篇文章主要为大家展示了Percona 5.5如何定位未使用的索引，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下Percona 5.5如何定位未使用的索引这篇文章吧。 打开userstat参数，然后让MySQL运行一段时间。 之后可
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这篇文章主要为大家展示了“Percona 5.5如何定位未使用的索引”，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下“Percona 5.5如何定位未使用的索引”这篇文章吧。 打开userstat参数，然后让MySQL运行一段时间。 之后可以在INFORMATION_SCHEMA.INDEX_STATISTICS表中查询到索引的使用频率。 mysql> show global variables like '%users%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | userstat | OFF | +---------------+-------+ 1 row in set (0.00 sec) mysql> select * from information_schema.index_statistics; Empty set (0.00 sec) mysql> set global userstat=1; Query OK, 0 rows affected (0.00 sec) mysql> show global variables like '%users%'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | userstat | ON | +---------------+-------+ 1 row in set (0.00 sec) mysql> select * from information_schema.index_statistics; Empty set (0.00 sec) mysql> explain select * from emp where hiredate > '1982-01-01' and deptno = 20; +----+-------------+-------+-------+---------------------------+------------------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+-------+---------------------------+------------------+---------+------+------+-------------+ | 1 | SIMPLE | emp | range | idx_date_sal_job,idx_date | idx_date_sal_job | 4 | NULL | 3 | Using where | +----+-------------+-------+-------+---------------------------+------------------+---------+------+------+-------------+ 1 row in set (0.00 sec) mysql> select * from information_schema.index_statistics; Empty set (0.00 sec) mysql> select * from emp where hiredate > '1982-01-01' and deptno = 20; +-------+-------+---------+------+---------------------+------+------+--------+ | empno | ename | job | mgr | hiredate | sal | comm | deptno | +-------+-------+---------+------+---------------------+------+------+--------+ | 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000 | NULL | 20 | | 7876 | ADAMS | CLERK | 7788 | 1983-01-12 00:00:00 | 1100 | NULL | 20 | +-------+-------+---------+------+---------------------+------+------+--------+ 2 rows in set (0.00 sec) mysql> select * from information_schema.index_statistics; +--------------+------------+------------------+-----------+ | TABLE_SCHEMA | TABLE_NAME | INDEX_NAME | ROWS_READ | +--------------+------------+------------------+-----------+ | test | emp | idx_date_sal_job | 3 | +--------------+------------+------------------+-----------+ 1 row in set (0.04 sec) mysql> select * from emp; +-------+--------+-----------+------+---------------------+------+------+--------+ | empno | ename | job | mgr | hiredate | sal | comm | deptno | +-------+--------+-----------+------+---------------------+------+------+--------+ | 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 | | 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600 | 300 | 30 | | 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 | | 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975 | NULL | 20 | | 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 | | 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850 | NULL | 30 | | 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 | | 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000 | NULL | 20 | | 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL | 10 | | 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 | | 7876 | ADAMS | CLERK | 7788 | 1983-01-12 00:00:00 | 1100 | NULL | 20 | | 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 | | 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000 | NULL | 20 | | 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 | +-------+--------+-----------+------+---------------------+------+------+--------+ 14 rows in set (0.00 sec) mysql> select * from information_schema.index_statistics; +--------------+------------+------------------+-----------+ | TABLE_SCHEMA | TABLE_NAME | INDEX_NAME | ROWS_READ | +--------------+------------+------------------+-----------+ | test | emp | PRIMARY | 14 | | test | emp | idx_date_sal_job | 3 | +--------------+------------+------------------+-----------+ 2 rows in set (0.00 sec) mysql> select * from emp where hiredate > '1982-01-01' and deptno = 20; +-------+-------+---------+------+---------------------+------+------+--------+ | empno | ename | job | mgr | hiredate | sal | comm | deptno | +-------+-------+---------+------+---------------------+------+------+--------+ | 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000 | NULL | 20 | | 7876 | ADAMS | CLERK | 7788 | 1983-01-12 00:00:00 | 1100 | NULL | 20 | +-------+-------+---------+------+---------------------+------+------+--------+ 2 rows in set (0.00 sec) mysql> select * from emp; +-------+--------+-----------+------+---------------------+------+------+--------+ | empno | ename | job | mgr | hiredate | sal | comm | deptno | +-------+--------+-----------+------+---------------------+------+------+--------+ | 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 | | 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600 | 300 | 30 | | 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 | | 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975 | NULL | 20 | | 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 | | 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850 | NULL | 30 | | 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 | | 7788 | SCOTT | ANALYST | 7566 | 1982-12-09 00:00:00 | 3000 | NULL | 20 | | 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL | 10 | | 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 | | 7876 | ADAMS | CLERK | 7788 | 1983-01-12 00:00:00 | 1100 | NULL | 20 | | 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 | | 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000 | NULL | 20 | | 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 | +-------+--------+-----------+------+---------------------+------+------+--------+ 14 rows in set (0.00 sec) mysql> select * from information_schema.index_statistics; +--------------+------------+------------------+-----------+ | TABLE_SCHEMA | TABLE_NAME | INDEX_NAME | ROWS_READ | +--------------+------------+------------------+-----------+ | test | emp | PRIMARY | 28 | | test | emp | idx_date_sal_job | 6 | +--------------+------------+------------------+-----------+ 2 rows in set (0.00 sec) 以上是“Percona 5.5如何定位未使用的索引”这篇文章的所有内容，感谢各位的阅读！ （编辑：汉中站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
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