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

标签：ror   line   mysql   table   btree   name   查找   slowlog   base   

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

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

标签：ror   line   mysql   table   btree   name   查找   slowlog   base   

原文地址：https://www.cnblogs.com/sunkang-dba/p/11926351.html