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Let me tell you a little bit about mysql slow query view. Have you learned about similar topics before? If you are interested, let's take a look at this article. I believe it will be of some help to you after reading the mysql slow query.

MYSQL slow query

First, check the status of all the parameters of the system:

Mysql > show variables

2. View the definition of slow query:

Mysql > show variables like'% quer%'

| | log_slow_queries | ON |

| | long_query_time | 5.000000 | |

Mysql > show variables like 'slow%'

+-- +

| | Variable_name | Value |

+-- +

| | slow_launch_time | 5 | |

| | slow_query_log | ON |

| | slow_query_log_file | / var/log/mysql/slow_query_log |

+-- +

3 rows in set (0.00 sec)

3. Modify the definition of slow query:

1. Modify now:

Enable slow query function, time definition

Mysql > SET log_slow_queries=on

Mysql > SET long_query_time=5

Enable slow query record function, time definition, file storage location

Mysql > SET slow_query_log=on

Mysql > SET slow_launch_time=5

Mysql > SET slow_query_log_file=/var/log/mysql/slow_query_log

two。 Modify the configuration file (need to restart the service)

Vim / etc/my.cnf

Enable slow query function, time definition

Log_slow_queries=on | off

Long_query_time=5

Enable slow query record function, time definition, file storage location

Slow_query_log=on | off

Slow_launch_time=5

Slow_query_log_file=/var/log/mysql/slow_query_log

Restart the service

Service mysql restart

IV. Other settings

1. Record all queries that do not use the index

Log_queries_not_using_indexes=on | off

two。 Record slow queries caused by more than 1000 searches

Min_examined_row_limit=1000

3. Record those slow OPTIMIZE TABLE,ANALYZE TABLE and ALTER TABLE statements

Log-slow-admin-statements

4. Record slow queries generated by slave

Log-slow-slave-statements

Log analysis tool mysqldumpslow

-s, which indicates how to sort:

C: access count

L: lock time

R: returns the record

T: query time

Al: average lock time

Ar: the average number of records returned

At: average query time

-t, which means top n, that is, how many previous pieces of data are returned.

-g, a regular matching pattern can be written later, which is case-insensitive.

Example:

1. Get the top 10 SQL that returns the recordset.

Mysqldumpslow-s r-t 10 / var/log/mysql/slow_query_log/mysql06_slow.log

two。 Get the 10 most visited SQL

Mysqldumpslow-s c-t 10 / var/log/mysql/slow_query_log/mysql06_slow.log

3. Get the query statements with left links in the first 10 items sorted by time.

Mysqldumpslow-s t-t 10-g "left join" / var/log/mysql/slow_query_log/mysql06_slow.log

4. It is also recommended to use these commands in combination with | and more, otherwise screen brushing may occur.

Mysqldumpslow-s r-t 20 / var/log/mysql/slow_query_log/mysql06-slow.log | more

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