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percona-toolkit之pt-index-usage和pt-duplicate-key-checker详解

原创 MySQL 作者:DBA_每日记 时间:2019-11-25 10:38:22 0 删除 编辑

1>

pt-index-usage:从慢查询日志中读取查询并分析它们如何使用索引。  (用来查找不常使用索引)


./pt-index-usage --help


打印报告

./pt-index-usage  /mysqldata/mysqlslowlog/slowquery.log -h192.168.226.131 -uroot -p6yhn^YHN -decology


[mysql@mysql bin]$ ./pt-index-usage  /mysqldata/mysqlslowlog/slowquery.log -h192.168.226.131 -uroot -p6yhn^YHN 

DBD::mysql::db selectall_arrayref failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/' at line 1 [for Statement "EXPLAIN SELECT IFNULL(SUM(INDEX_LENGTH),0) from information_schema.TABLES where ENGINE='InnoDB' */"] at ./pt-index-usage line 4598, <> line 1.

DBD::mysql::db selectall_arrayref failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/' at line 1 [for Statement "EXPLAIN SELECT IFNULL(SUM(DATA_LENGTH),0) from information_schema.TABLES where ENGINE='InnoDB' */"] at ./pt-index-usage line 4598, <> line 2.

DBD::mysql::db selectall_arrayref failed: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '/' at line 1 [for Statement "EXPLAIN SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE='BASE TABLE' */"] at ./pt-index-usage line 4598, <> line 4.


ALTER TABLE `test1`.`user` DROP KEY `idx_1`; -- type:non-unique


2>  pt-duplicate-key-checker检查数据库的重复索引

索引会更查询带来好处,但是过量的索引反而可能会使数据库的性能降低


./pt-duplicate-key-checker --help


1> 表结构

[root@localhost][test1]> show index from user;

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+

| user  |          0 | PRIMARY  |            1 | id          | A         |     1042305 |     NULL | NULL   |      | BTREE      |         |               |

| user  |          1 | idx_1    |            1 | id          | A         |     1042305 |     NULL | NULL   |      | BTREE      |         |               |

+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+


字段id有两个索引,


[mysql@mysql bin]$ ./pt-duplicate-key-checker -uroot -p6yhn^YHN

# ########################################################################

# test1.user                                                              

# ########################################################################


# idx_1 is a duplicate of PRIMARY

# Key definitions:

#   KEY `idx_1` (`id`)

#   PRIMARY KEY (`id`),

# Column types:

#         `id` int(11) not null auto_increment

# To remove this duplicate index, execute:

ALTER TABLE `test1`.`user` DROP INDEX `idx_1`;


# ########################################################################

# Summary of indexes                                                      

# ########################################################################


# Size Duplicate Indexes   4169220

# Total Duplicate Indexes  1

# Total Indexes            34




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