Official answer | The variables in the slow_query_log_file instance memory are inconsistent with the settings in the configuration file.
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This question comes from the forum. The user’s database environment is roughly introduced as follows:
| name | Version |
|---|---|
| Operating system version | BigCloud Enterprise Linux 8 |
| Database version | GreatSQL-8.0.32-25 |
User issues
The problem information provided by the user is as follows:
1. My.cnf configuration file slowly log file path related configuration:
slow_query_log_file = /data/GreatSQL/logs/slow.log
slow_query_log_file2. However, the variables found in the memory are inconsistent with the configuration.
mysqladmin var |grep slow_query_log_file
| slow_query_log_file | /data/GreatSQL/logs/bclinux01.log.000001
Answer user questions
1. Why is the name of the slow log file generated on the disk (under the /data/GreatSQL directory) inconsistent with the variables queried in the memory and those set in the configuration file?
Raising a question: Have you ever modified the binlog configuration and modified slow_query_log_file by mistake?
This problem occurs when the configuration file is written asslow_query_log_file = /data/GreatSQL/logs/slow.log
show global variables like '%slow%';Display in memory/data/GreatSQL/logs/bclinux01.log
set global slow_query_log_file='/data/GreatSQL/logs/bclinux01.log'It can only be reproduced through SQL commands .
2. If you slow_query_log_file = /data/GreatSQL/logs/slow.logcomment out the configuration information in the configuration file, the file name on the disk is still bclinux01.log.000001
After commenting this parameter in the my.cnf configuration file slow_query_log_file = /data/GreatSQL/logs/slow.log, if the database instance is not restarted, set global slow_query_log_filethe parameters that have been modified before will not have any parameter variable impact; if the database instance is restarted, the slow log file name is updated to the host name-slow.log
The user asked why the slow log contains 0000001 and multiple slow.log.xxxxxx files are always generated. The reason is that the following parameters are configured. When the following parameters are configured, the database will poll to generate slow.log.xxxxxx files.
max_slowlog_size = [0 - 1073741824]
max_slowlog_files = [0 - 102400]
- max_slowlog_size
When the size of the log reaches the set value, the server will poll the slow log. The default value is 0. If the size is limited and this feature is enabled, the server renames the slow log file to slow_query_log_file.000001
- max_slowlog_files
This variable limits the total size of slow log files and is used together with max_slowlog_size
The server creates and adds slow logs until the upper limit of the range is reached. When the maximum is reached, the server creates a new slow log file with a higher sequence number and deletes the log file with the lowest sequence number to keep the total amount defined within the range.
Solve user problems
After passing set global slow_query_log_file = '/data/GreatSQL/slow.log'the settings, check the memory data again, and the display will be correct:
greatsql> show global variables like '%slow%';
| slow_query_log_file | /data/GreatSQL/slow.log.000001 |
Enjoy GreatSQL :)
About GreatSQL
GreatSQL is a domestic independent open source database suitable for financial-level applications. It has many core features such as high performance, high reliability, high ease of use, and high security. It can be used as an optional replacement for MySQL or Percona Server and is used in online production environments. , completely free and compatible with MySQL or Percona Server.
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