wdcp mysql日志文_mysql的日志简单总结

事务日志

redo log

mysql的innodb引擎在开启事务后，中间的操作都会先在内存中进行。然后将这些数据先写入到redo log中--“日志先行”(Write-Ahead Logging)，因为写入到rero log是磁盘某块区域的顺序写入，所以效率更高。事务提交后也不一定就立刻将redo日志里的数据写入磁盘，一般是慢慢刷新分批写入到磁盘，减轻数据库压力。如果数据库崩溃或者机器宕机，系统重启或恢复的时候，可以根据redo log中的日志信息，将已完成的事务操作写入到数据库中，而对未完成的事务则进行回滚。

undo log

uodo log只有负责数据的回滚，一般保存的是事务执行操作的前的状态。

相关变量

mysql> show variables like '%innodb_log%';

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

| Variable_name | Value |

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

| innodb_log_buffer_size | 16777216 |

| innodb_log_checksums | ON |

| innodb_log_compressed_pages | ON |

| innodb_log_file_size | 50331648 | #单个日志文件的大小

| innodb_log_files_in_group | 2 | #日志个数

| innodb_log_group_home_dir | ./ | #事务日志路径

| innodb_log_spin_cpu_abs_lwm | 80 |

| innodb_log_spin_cpu_pct_hwm | 50 |

| innodb_log_wait_for_flush_spin_hwm | 400 |

| innodb_log_write_ahead_size | 8192 |

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

10 rows in set (0.00 sec)

mysql> show variables like '%innodb_flush_log%';

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

| Variable_name | Value |

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

| innodb_flush_log_at_timeout | 1 |

| innodb_flush_log_at_trx_commit | 1 | #事务提交策略，建议修改为2

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

2 rows in set (0.00 sec)

错误日志

记录mysqld启动，运行和结束中输出的错误或警告信息

相关变量

mysql> show variables like 'log_error%';

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

| Variable_name | Value |

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

| log_error | /var/log/mysqld.log | #错误日志存放路径

| log_error_services | log_filter_internal; log_sink_internal |

| log_error_suppression_list | |

| log_error_verbosity | 2 | #mysql5.7.2后出现的系统变量，代替原来的log_warnings,错误日志的详细等级，数值越高越详细，注意：mysql 8.0,3之后版本已经移除了log_warnings变量。

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

4 rows in set (0.00 sec)

通用日志

记录客户端对数据库的各种操作，包括sql语句执行记录等。

相关变量

mysql> show variables like 'general_log%';

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

| Variable_name | Value |

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

| general_log | OFF | #默认未启用状态

| general_log_file | /var/lib/mysql/centos7.log | #日志存放路径

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

2 rows in set (0.00 sec)

mysql> show variables like 'log_output';

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

| Variable_name | Value |

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

| log_output | FILE | #日志存放类型，有none，file，table三种类型。

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

1 row in set (0.00 sec)

慢查询日志

记录执行时间超过long_query_time变量设置时间的查询，也可以记录一些没有使用索引的sql。

相关变量

mysql> show variables like 'slow_query%';

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

| Variable_name | Value |

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

| slow_query_log | OFF | #默认未开启

| slow_query_log_file | /var/lib/mysql/centos7-slow.log | #日志存放路径

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

2 rows in set (0.01 sec)

mysql> show variables like 'long_query%';

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

| Variable_name | Value |

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

| long_query_time | 10.000000 | #超过这个时长的查询将会被记录

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

1 row in set (0.00 sec)

mysql> show variables like 'log_queries%';

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

| Variable_name | Value |

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

| log_queries_not_using_indexes | OFF | #开启此项后，没有使用索引的sql也将被记录

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

1 row in set (0.00 sec)

慢查询相关分析工具

mysqldumpslow

profile

mysql> select @@profiling;

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

| @@profiling |

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

| 0 |

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

1 row in set, 1 warning (0.01 sec)

mysql> set profiling=1;

Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> show tables;

ERROR 1046 (3D000): No database selected

mysql> show databases;

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

| Database |

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

| information_schema |

| mysql |

| performance_schema |

| sys |

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

4 rows in set (0.01 sec)

mysql> create tables t1(id int);

ERROR 1064 (42000): 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 'tables t1(id int)' at line 1

mysql> show profiles;

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

| Query_ID | Duration | Query |

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

| 1 | 0.00010625 | show tables |

| 2 | 0.01226175 | show databases |

| 3 | 0.00008175 | create tables t1(id int) |

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

3 rows in set, 1 warning (0.00 sec)

mysql> show profile;

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

| Status | Duration |

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

| starting | 0.000062 |

| freeing items | 0.000014 |

| cleaning up | 0.000006 |

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

3 rows in set, 1 warning (0.01 sec)

mysql> show profile for query 2;

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

| Status | Duration |

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

| starting | 0.008047 |

| checking permissions | 0.000024 |

| Opening tables | 0.001117 |

| init | 0.000585 |

| System lock | 0.000035 |

| optimizing | 0.000205 |

| statistics | 0.000504 |

| preparing | 0.000191 |

| Creating tmp table | 0.000337 |

| executing | 0.000841 |

| end | 0.000027 |

| query end | 0.000006 |

| waiting for handler commit | 0.000021 |

| removing tmp table | 0.000006 |

| waiting for handler commit | 0.000006 |

| closing tables | 0.000016 |

| freeing items | 0.000277 |

| cleaning up | 0.000020 |

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

18 rows in set, 1 warning (0.00 sec)

mysql> show profile cpu for query 2;

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

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

| starting | 0.008047 | 0.008023 | 0.000000 |

| checking permissions | 0.000024 | 0.000015 | 0.000000 |

| Opening tables | 0.001117 | 0.001128 | 0.000000 |

| init | 0.000585 | 0.000582 | 0.000000 |

| System lock | 0.000035 | 0.000027 | 0.000000 |

| optimizing | 0.000205 | 0.000208 | 0.000000 |

| statistics | 0.000504 | 0.000503 | 0.000000 |

| preparing | 0.000191 | 0.000191 | 0.000000 |

| Creating tmp table | 0.000337 | 0.000338 | 0.000000 |

| executing | 0.000841 | 0.000847 | 0.000000 |

| end | 0.000027 | 0.000016 | 0.000000 |

| query end | 0.000006 | 0.000006 | 0.000000 |

| waiting for handler commit | 0.000021 | 0.000020 | 0.000000 |

| removing tmp table | 0.000006 | 0.000007 | 0.000000 |

| waiting for handler commit | 0.000006 | 0.000006 | 0.000000 |

| closing tables | 0.000016 | 0.000016 | 0.000000 |

| freeing items | 0.000277 | 0.000279 | 0.000000 |

| cleaning up | 0.000020 | 0.000018 | 0.000000 |

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

18 rows in set, 1 warning (0.00 sec)

二进制日志

记录会引起数据改变的SQL。多用于数据还原和主从复制

相关变量

sql_log_bin #是否开启二进制日志

log_bin #指定文件位置

binlog_format #默认格式statement，建议根据需求改为row和mixed

max_binlog_size #单个二进制日志最大体积，默认1G

expire_logs_days #二进制日志自动删除的天数，默认为0

二进制日志相关命令

# 查看二进制日志文件列表和大小

mysql> show master logs;

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

| Log_name | File_size | Encrypted |

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

| bin-log.000001 | 32388 | No |

| bin-log.000002 | 156 | No |

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

2 rows in set (0.00 sec)

mysql> show binary logs;

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

| Log_name | File_size | Encrypted |

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

| bin-log.000001 | 32388 | No |

| bin-log.000002 | 156 | No |

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

2 rows in set (0.00 sec)

# 查看正在使用的二进制日志文件

mysql> show master status;

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

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

| bin-log.000002 | 156 | | | |

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

1 row in set (0.00 sec)

# 查看二进制文件内容

mysql> show binlog events;

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

| bin-log.000001 | 4 | Format_desc | 1 | 125 | Server ver: 8.0.21, Binlog ver: 4 |

| bin-log.000001 | 125 | Previous_gtids | 1 | 156 | |

| bin-log.000001 | 156 | Anonymous_Gtid | 1 | 235 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS' |

| bin-log.000001 | 235 | Query | 1 | 418 | CREATE DATABASE /*!32312 IF NOT EXISTS*/ `hellodb` /*!40100 DEFAULT CHARACTER SET utf8 */ /* xid=16 */ |

| bin-log.000001 | 418 | Anonymous_Gtid | 1 | 495 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS' |

| bin-log.000001 | 495 | Query | 1 | 634 | use `hellodb`; DROP TABLE IF EXISTS `classes` /* generated by server */ |

| bin-log.000001 | 634 | Anonymous_Gtid | 1 | 713 | SET @@SESSION.GTID_NEXT= 'ANONYMOUS'

# 删除二进制文件

PURGE BINARY LOGS TO 'mysql-bin.00001';

PURGE BINARY LOGS BEFORE '2020-10-10 10:10:10';

RESET MASTER TO 1234;

SHOW BINARY LOGS;

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

| Log_name | File_size | Encrypted |

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

| master-bin.001234 | 154 | No |

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

#切换日志文件

flush logs；

二进制日志客户端查看工具

mysqlbinlog

[root@centos7 mysql]#mysqlbinlog bin-log.000002

/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;

/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;

DELIMITER /*!*/;

# at 4

#201013 22:29:02 server id 1 end_log_pos 125 CRC32 0x8f94c3aa Start: binlog v 4, server v 8.0.21 created 201013 22:29:02 at startup

# Warning: this binlog is either in use or was not closed properly.

ROLLBACK/*!*/;

BINLOG '

rrmFXw8BAAAAeQAAAH0AAAABAAQAOC4wLjIxAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAACuuYVfEwANAAgAAAAABAAEAAAAYQAEGggAAAAICAgCAAAACgoKKioAEjQA

CigBqsOUjw==

'/*!*/;

# at 125

#201013 22:29:02 server id 1 end_log_pos 156 CRC32 0x5873f06a Previous-GTIDs

# [empty]

SET @@SESSION.GTID_NEXT= 'AUTOMATIC' /* added by mysqlbinlog */ /*!*/;

DELIMITER ;

# End of log file

/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;

/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

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