目录
如果不知道错误日志的位置可以登录mysql服务查找错误日志变量
localhost-bin.index 文件:记录了累计共有多少个二进制文件
查看当前使用的是哪个二进制文件 show master status
一个二进制文件是否记录了整个mysqld进程里所有的库的操作?
日志用来做什么事?
1、用来排错。
2、用来做数据分析,提升数据库性能等
3、了解程序的运行情况,是否健康,了解mysql性能,运行情况
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一般错误日志的名字是 : 主机名.err
错误日志是Mysq里面默认开启的日志。
- root@(none) 10:28 mysql>show variables like "%log%";
- +--------------------------------------------+---------------------------------------+
- | Variable_name | Value |
- +--------------------------------------------+---------------------------------------+
- | back_log | 80 |
- | binlog_cache_size | 32768 |
- | binlog_checksum | CRC32 |
- | binlog_direct_non_transactional_updates | OFF |
- | binlog_error_action | ABORT_SERVER |
- | binlog_format | ROW |
- | binlog_group_commit_sync_delay | 0 |
- | binlog_group_commit_sync_no_delay_count | 0 |
- | binlog_gtid_simple_recovery | ON |
- | binlog_max_flush_queue_time | 0 |
- | binlog_order_commits | ON |
- | binlog_row_image | FULL |
- | binlog_rows_query_log_events | OFF |
- | binlog_stmt_cache_size | 32768 |
- | binlog_transaction_dependency_history_size | 25000 |
- | binlog_transaction_dependency_tracking | COMMIT_ORDER |
- | expire_logs_days | 0 |
- | general_log | OFF |
- | general_log_file | /data/mysql/localhost.log |
- | innodb_api_enable_binlog | OFF |
- | innodb_flush_log_at_timeout | 1 |
- | innodb_flush_log_at_trx_commit | 1 |
- | innodb_locks_unsafe_for_binlog | OFF |
- | innodb_log_buffer_size | 16777216 |
- | innodb_log_checksums | ON |
- | innodb_log_compressed_pages | ON |
- | innodb_log_file_size | 50331648 |
- | innodb_log_files_in_group | 2 |
- | innodb_log_group_home_dir | ./ |
- | innodb_log_write_ahead_size | 8192 |
- | innodb_max_undo_log_size | 1073741824 |
- | innodb_online_alter_log_max_size | 134217728 |
- | innodb_undo_log_truncate | OFF |
- | innodb_undo_logs | 128 |
- | log_bin | OFF |
- | log_bin_basename | |
- | log_bin_index | |
- | log_bin_trust_function_creators | OFF |
- | log_bin_use_v1_row_events | OFF |
- | log_builtin_as_identified_by_password | OFF |
- | log_error | ./localhost.localdomain.err |
- | log_error_verbosity | 3 |
- | log_output | FILE |
- | log_queries_not_using_indexes | OFF |
- | log_slave_updates | OFF |
- | log_slow_admin_statements | OFF |
- | log_slow_slave_statements | OFF |
- | log_statements_unsafe_for_binlog | ON |
- | log_syslog | OFF |
- | log_syslog_facility | daemon |
- | log_syslog_include_pid | ON |
- | log_syslog_tag | |
- | log_throttle_queries_not_using_indexes | 0 |
- | log_timestamps | UTC |
- | log_warnings | 2 |
- | max_binlog_cache_size | 18446744073709547520 |
- | max_binlog_size | 1073741824 |
- | max_binlog_stmt_cache_size | 18446744073709547520 |
- | max_relay_log_size | 0 |
- | relay_log | |
- | relay_log_basename | /data/mysql/localhost-relay-bin |
- | relay_log_index | /data/mysql/localhost-relay-bin.index |
- | relay_log_info_file | relay-log.info |
- | relay_log_info_repository | FILE |
- | relay_log_purge | ON |
- | relay_log_recovery | OFF |
- | relay_log_space_limit | 0 |
- | slow_query_log | OFF |
- | slow_query_log_file | /data/mysql/localhost-slow.log |
- | sql_log_bin | ON |
- | sql_log_off | OFF |
- | sync_binlog | 1 |
- | sync_relay_log | 10000 |
- | sync_relay_log_info | 10000 |
- +--------------------------------------------+---------------------------------------+
- 74 rows in set (0.00 sec)
因为我的mysql服务是二进制安装的,我们指定了数据目录,错误日志会放在数据目录里面。
- [root@localhost mysql]# ls
- auto.cnf ibdata1 mysql sanchuang ucar_cloud
- ca-key.pem ib_logfile0 mysql.sock server-cert.pem wangsh
- ca.pem ib_logfile1 mysql.sock.lock server-key.pem
- client-cert.pem ibtmp1 performance_schema student
- client-key.pem localhost.localdomain.err private_key.pem sys
- ib_buffer_pool localhost.localdomain.pid public_key.pem test
- [root@localhost mysql]#
- root@(none) 10:34 mysql>show variables like "log_error";
- +---------------+-----------------------------+
- | Variable_name | Value |
- +---------------+-----------------------------+
- | log_error | ./localhost.localdomain.err |
- +---------------+-----------------------------+
- 1 row in set (0.01 sec)
登录失败会记录到错误日志
配置文件出错也会记录
启动过程出问题也会记录
使用tail -f 监控日志文件
[root@localhost mysql]# tail -f localhost.localdomain.err
错误输入密码:
生成错误日志:
日志文件配置错误:
生成警告
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作用:记录消耗时间比较长的SQL语句,为数据库性能提升提供了线索
最近数据库压力(负载特别高),客户反应网站或者应用使用特别慢,领导要求你查明原因?
1.SQL语句需要优化,在数据库里启用慢日志,找出执行时间比较长的SQL
2.业务量太大了,硬件已经达到极限了 ,top、glances、dstat
慢日志默认是关闭的
如果打开慢日志会将慢日志放在我们定义的数据目录下面。名字是主机名 + slow.log
- root@(none) 10:57 mysql>show variables like "%slow_query%";
- +---------------------+--------------------------------+
- | Variable_name | Value |
- +---------------------+--------------------------------+
- | slow_query_log | OFF |
- | slow_query_log_file | /data/mysql/localhost-slow.log |
- +---------------------+--------------------------------+
- 2 rows in set (0.00 sec)
默认sql语句超过10秒就是慢sql,会记录到慢日志
- root@(none) 10:45 mysql>show variables like "%long_query%";
- +-----------------+-----------+
- | Variable_name | Value |
- +-----------------+-----------+
- | long_query_time | 10.000000 |
- +-----------------+-----------+
- 1 row in set (0.00 sec)
- # slow log
- slow_query_log = 1
- long_query_time = 0.001 # 标准
- # 在写入慢日志中包含慢管理语句。
- log_slow_admin_statements = 1
-
重启配置文件以后就会出现慢日志文件
- root@(none) 11:34 mysql>show variables like "%slow%";
- +---------------------------+--------------------------------+
- | Variable_name | Value |
- +---------------------------+--------------------------------+
- | log_slow_admin_statements | ON |
- | log_slow_slave_statements | OFF |
- | slow_launch_time | 2 |
- | slow_query_log | ON |
- | slow_query_log_file | /data/mysql/localhost-slow.log |
- +---------------------------+--------------------------------+
- 5 rows in set (0.01 sec)
-
- root@(none) 11:35 mysql>
我们设置了慢日志标准为0.001秒,如果有sql语句超过这个时间的话就会记录到 慢日志里面
- root@(none) 11:52 mysql>show variables like "%slow%";
- +---------------------------+--------------------------------+
- | Variable_name | Value |
- +---------------------------+--------------------------------+
- | log_slow_admin_statements | ON |
- | log_slow_slave_statements | OFF |
- | slow_launch_time | 2 |
- | slow_query_log | ON |
- | slow_query_log_file | /data/mysql/localhost-slow.log |
- +---------------------------+--------------------------------+
- 5 rows in set (0.01 sec)
-
- root@(none) 11:52 mysql>
##########################################################################
general 日志,会记录所有的sql操作
缺点:会消耗大量的磁盘空间,消耗cpu,内存,磁盘资源
通用日志名字为 主机名 + .log
- root@(none) 12:13 mysql>show variables like "%general%";
- +------------------+---------------------------+
- | Variable_name | Value |
- +------------------+---------------------------+
- | general_log | OFF |
- | general_log_file | /data/mysql/localhost.log |
- +------------------+---------------------------+
- 2 rows in set (0.00 sec)
通用日志默认是关闭的,我们可以在配置文件里面打开通用日志。
- # general 日志
- general_log
- root@(none) 12:15 mysql>show variables like "%general%"
- -> ;
- +------------------+---------------------------+
- | Variable_name | Value |
- +------------------+---------------------------+
- | general_log | ON |
- | general_log_file | /data/mysql/localhost.log |
- +------------------+---------------------------+
- 2 rows in set (0.00 sec)
-
- root@(none) 12:15 mysql>
可以看到,开启general通用日志以后,所有使用过的sql语句都会记录在 localhost.log文件里面
- root@(none) 14:40 mysql>use wangsh;
- Reading table information for completion of table and column names
- You can turn off this feature to get a quicker startup with -A
-
- Database changed
- root@wangsh 14:40 mysql>show tables;
- +------------------+
- | Tables_in_wangsh |
- +------------------+
- | shirts |
- | tran_demo |
- +------------------+
- 2 rows in set (0.00 sec)
-
- root@wangsh 14:40 mysql>desc tran_demo;
- +-------+-------------+------+-----+---------+-------+
- | Field | Type | Null | Key | Default | Extra |
- +-------+-------------+------+-----+---------+-------+
- | id | int(11) | YES | | NULL | |
- | name | varchar(20) | YES | | NULL | |
- +-------+-------------+------+-----+---------+-------+
- 2 rows in set (0.00 sec)
-
- root@wangsh 14:40 mysql>
##########################################################################
可以用来做数据恢复
主从复制
二进制日志默认也是没有开启的。
- root@wangsh 14:51 mysql>show variables like "%log_bin%";
- +---------------------------------+-------+
- | Variable_name | Value |
- +---------------------------------+-------+
- | log_bin | OFF |
- | log_bin_basename | |
- | log_bin_index | |
- | log_bin_trust_function_creators | OFF |
- | log_bin_use_v1_row_events | OFF |
- | sql_log_bin | ON |
- +---------------------------------+-------+
- 6 rows in set (0.00 sec)
- # binary log
- log_bin
- server_id = 1
- root@(none) 14:54 mysql>show variables like "%log_bin%";
- +---------------------------------+---------------------------------+
- | Variable_name | Value |
- +---------------------------------+---------------------------------+
- | log_bin | ON |
- | log_bin_basename | /data/mysql/localhost-bin |
- | log_bin_index | /data/mysql/localhost-bin.index |
- | log_bin_trust_function_creators | OFF |
- | log_bin_use_v1_row_events | OFF |
- | sql_log_bin | ON |
- +---------------------------------+---------------------------------+
- 6 rows in set (0.00 sec)
-
- root@(none) 14:56 mysql>
- [root@localhost mysql]# ls
- auto.cnf ib_logfile1 mysql server-key.pem
- ca-key.pem ibtmp1 mysql.sock student
- ca.pem localhost-bin.000001 mysql.sock.lock sys
- client-cert.pem localhost-bin.index performance_schema test
- client-key.pem localhost.localdomain.err private_key.pem ucar_cloud
- ib_buffer_pool localhost.localdomain.pid public_key.pem wangsh
- ibdata1 localhost.log sanchuang
- ib_logfile0 localhost-slow.log server-cert.pem
- [root@localhost mysql]#
mysqld服务每刷新一次,二进制文件就会增加一个,index文件里面也会新加一个
- [root@localhost mysql]# ls
- auto.cnf ib_logfile1 mysql server-key.pem
- ca-key.pem ibtmp1 mysql.sock student
- ca.pem localhost-bin.000001 mysql.sock.lock sys
- client-cert.pem localhost-bin.index performance_schema test
- client-key.pem localhost.localdomain.err private_key.pem ucar_cloud
- ib_buffer_pool localhost.localdomain.pid public_key.pem wangsh
- ibdata1 localhost.log sanchuang
- ib_logfile0 localhost-slow.log server-cert.pem
- [root@localhost mysql]# cat localhost-bin.index
- ./localhost-bin.000001
- [root@localhost mysql]# service mysqld restart
- Shutting down MySQL.... SUCCESS!
- Starting MySQL. SUCCESS!
- [root@localhost mysql]# ls
- auto.cnf ib_logfile1 localhost-slow.log server-cert.pem
- ca-key.pem ibtmp1 mysql server-key.pem
- ca.pem localhost-bin.000001 mysql.sock student
- client-cert.pem localhost-bin.000002 mysql.sock.lock sys
- client-key.pem localhost-bin.index performance_schema test
- ib_buffer_pool localhost.localdomain.err private_key.pem ucar_cloud
- ibdata1 localhost.localdomain.pid public_key.pem wangsh
- ib_logfile0 localhost.log sanchuang
- [root@localhost mysql]# cat localhost-bin.index
- ./localhost-bin.000001
- ./localhost-bin.000002
- root@(none) 15:00 mysql>show master status;
- +----------------------+----------+--------------+------------------+-------------------+
- | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
- +----------------------+----------+--------------+------------------+-------------------+
- | localhost-bin.000002 | 154 | | | |
- +----------------------+----------+--------------+------------------+-------------------+
- 1 row in set (0.00 sec)
-
- root@(none) 15:00 mysql>
- root@(none) 15:03 mysql>show binary logs;
- +----------------------+-----------+
- | Log_name | File_size |
- +----------------------+-----------+
- | localhost-bin.000001 | 177 |
- | localhost-bin.000002 | 205 |
- | localhost-bin.000003 | 154 |
- +----------------------+-----------+
- 3 rows in set (0.00 sec)
-
- root@(none) 15:07 mysql>
是的,对所有库的操作都会记录到一个二进制文件里面,如果需要记录到不同的日志文件里面,可以采用多实例
mysq实例:
正在运行的一个mysql进程,这个进程里面有哪些库可以操作,二进制日志就记录哪些库的操作
多实例:
多启动几个mysqld的进程,一个mysqld的进程对应一个库
隔离应用,避免一个库使用特别频繁,影响其他的库
多实例任然受到整个机器整体系统资源的限制
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- root@(none) 15:00 mysql>flush logs;
- Query OK, 0 rows affected (0.00 sec)
-
- root@(none) 15:03 mysql>show master status;
- +----------------------+----------+--------------+------------------+-------------------+
- | File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
- +----------------------+----------+--------------+------------------+-------------------+
- | localhost-bin.000003 | 154 | | | |
- +----------------------+----------+--------------+------------------+-------------------+
- 1 row in set (0.00 sec)
-
- root@(none) 15:03 mysql>
- [root@localhost mysql]# ls
- auto.cnf ib_logfile1 localhost.log sanchuang
- ca-key.pem ibtmp1 localhost-slow.log server-cert.pem
- ca.pem localhost-bin.000001 mysql server-key.pem
- client-cert.pem localhost-bin.000002 mysql.sock student
- client-key.pem localhost-bin.000003 mysql.sock.lock sys
- ib_buffer_pool localhost-bin.index performance_schema test
- ibdata1 localhost.localdomain.err private_key.pem ucar_cloud
- ib_logfile0 localhost.localdomain.pid public_key.pem wangsh
- [root@localhost mysql]#
- root@(none) 15:07 mysql>show variables like "max_binlog_size";
- +-----------------+------------+
- | Variable_name | Value |
- +-----------------+------------+
- | max_binlog_size | 1073741824 |
- +-----------------+------------+
- 1 row in set (0.00 sec)
-
- root@(none) 15:15 mysql>
- root@(none) 15:15 mysql>select 1073741824/1024/1024;
- +----------------------+
- | 1073741824/1024/1024 |
- +----------------------+
- | 1024.00000000 |
- +----------------------+
- 1 row in set (0.00 sec)
-
- root@(none) 15:17 mysql>
##########################################################################
此时我们使用的二进制文件是 Localhost-bin.000003
对数据库进行操作
- root@ucar_cloud 15:33 mysql>use student;
- Database changed
- root@student 15:34 mysql>shwo tables;
- 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 'shwo tables' at line 1
- root@student 15:34 mysql>show tables;
- Empty set (0.00 sec)
-
- root@student 15:34 mysql>create table test(id int, name varchar(20));
- Query OK, 0 rows affected (0.01 sec)
-
- root@student 15:35 mysql>insert into test(id,name) values(1,'wang');
- Query OK, 1 row affected (0.00 sec)
- [root@localhost mysql]# mysqlbinlog -v localhost-bin.000003
- # at 535
- #220812 15:35:34 server id 1 end_log_pos 580 CRC32 0xdd2e8bd1 Write_rows: table id 113 flags: STMT_END_F
-
- BINLOG '
- xgL2YhMBAAAANQAAABcCAAAAAHEAAAAAAAEAB3N0dWRlbnQABHRlc3QAAgMPAjwAA5EKdrY=
- xgL2Yh4BAAAALQAAAEQCAAAAAHEAAAAAAAEAAgAC//wBAAAABHdhbmfRiy7d
- '/*!*/;
- ### INSERT INTO `student`.`test`
- ### SET
- ### @1=1
- ### @2='wang'
at 535 从535位置号开始
220812 15:35:34 时间
end_log_pos 580 到 580位置号结束
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redo log的作用:
redo log的主要作用是用于数据库的崩溃恢复
就是当数据从内存刷到磁盘的时候,突然停电,导致刷盘失败,然后Mysql服务器重启后就会首先看redolog的日志,重新再做一遍,保障数据一致性,不丢失
一是内存中重做日志缓冲 (redo log buffer),是易失的,在内存中
二是重做日志文件 (redo log file),是持久的,保存在磁盘中
redo日志是比数据页先写入磁盘的。
第一步:先将原始数据从磁盘中读入内存中来,修改数据的内存拷贝
第二步:生成一条重做日志并写入redo log buffer,记录的是数据被修改后的值
第三步:当事务commit时,将redo log buffer中的内容刷新到 redo log file,对 redo log file采用追加写的方式
第四步:定期将内存中修改的数据刷新到磁盘中
undolog的作用
undo log主要记录的是数据的逻辑变化,为了在发生错误时回滚之前的操作,需要将之前的操作都记录下来,然后在发生错误时才可以回滚。
服务器运行时的回滚rollback、MVCC(多版本控制)就是基于此log
##########################################################################
示例:状态1:A:10,B:10,状态2:A:0,B:20
过程:
1、从磁盘中读取数据A到内存中
2、记录数据到undo.log
3、修改A的值为0
4、记录修改后的数据到redo.log buffer 里面
5、从磁盘中读取数据B到内存中
6、记录数据到undo.log
7、修改B的值为20
8、记录修改后的数据到redo.log buffer 里面,server层标记prepare,准备提交
9、bin_log 写入磁盘中
10、事务提交,redo.log 在server层标记 commit,数据刷入磁盘中,提交成功,
如果中途失败的话,会根据undo.log回滚。
参考资料: