同大多数关系型数据库一样，日志文件是MySQL数据库的重要组成部分。MySQL有几种不同的日志文件，通常包括错误日志文件，二进制日志，通用日志，慢查询日志，等等。这些日志可以帮助我们定位mysqld内部发生的事件，数据库性能故障，记录数据的变更历史，用户恢复数据库等等。二进制日志，也叫binary log，是MySQL Server中最为重要的日志之一，本文主要描述二进制日志。

1、MySQL日志文件系统的组成
   a、错误日志：记录启动、运行或停止mysqld时出现的问题。
   b、通用日志：记录建立的客户端连接和执行的语句。
   c、更新日志：记录更改数据的语句。该日志在MySQL 5.1中已不再使用。
   d、二进制日志：记录所有更改数据的语句。还用于复制。
   e、慢查询日志：记录所有执行时间超过long_query_time秒的所有查询或不使用索引的查询。
   f、Innodb日志：innodb redo log
 
   缺省情况下，所有日志创建于mysqld数据目录中。
   可以通过刷新日志，来强制mysqld来关闭和重新打开日志文件（或者在某些情况下切换到一个新的日志）。
   当你执行一个FLUSH LOGS语句或执行mysqladmin flush-logs或mysqladmin refresh时，则日志被老化。
   对于存在MySQL复制的情形下，从复制服务器将维护更多日志文件，被称为接替日志。

2、二进制日志(Binary log)
  a、它包含的内容及作用如下：
    包含了所有更新了数据或者已经潜在更新了数据(比如没有匹配任何行的一个DELETE)
    包含关于每个更新数据库(DML)的语句的执行时间信息
    不包含没有修改任何数据的语句，如果需要启用该选项，需要开启通用日志功能
    主要目的是尽可能的将数据库恢复到数据库故障点，因为二进制日志包含备份后进行的所有更新
    用于在主复制服务器上记录所有将发送给从服务器的语句
    启用该选项数据库性能降低1%，但保障数据库完整性，对于重要数据库值得以性能换完整。有些类似于oracle开启归档模式。
  
  b、开启二进制日志的方法及属性
    使用--log-bin[=file_name]选项或在配置文件中指定log-bin启动时，mysqld写入包含所有更新数据的SQL命令的日志文件。
    对于未给出file_name值， 默认名为-bin后面所跟的主机名。
    在未指定绝对路径的情形下，缺省位置保存在数据目录下。
    每个二进制日志名会添加一个数字扩展名用于日志老化，因此不支持自定义的扩展名，会被mysql数字扩展名动态替换。
    若当前的日志大小达到max_binlog_size，则自动创建新的二进制日志。
    对于大的事务，二进制日志会超过max_binlog_size设定的值。也即是事务仅仅写入一个二进制日志。
    由是可知，二进制日志文件大小接近，其size不是完全相等，这点不同于oracle。
    二进制日志文件会有一个对应二进制日志索引文件，该文件包含所有的二进制日志，其文件名与二进制日志相同，扩展名为.index
    二进制索引文件通过--log-bin-index[=file_name]选项来指定
    RESET MASTER语句将删除所有二进制日志文件，这将影响到从库。也可以用PURGE MASTER LOGS只删除部分二进制文件。
  

3、二进制日志相关演示

a、启用二进制日志--当前环境root@localhost[(none)]> show variables like ‘%version%‘;+-------------------------+------------------------------+| Variable_name           | Value                        |+-------------------------+------------------------------+| innodb_version          | 5.5.39                       || protocol_version        | 10                           || slave_type_conversions  |                              || version                 | 5.5.39                       || version_comment         | MySQL Community Server (GPL) || version_compile_machine | x86_64                       || version_compile_os      | Linux                        |+-------------------------+------------------------------+root@localhost[(none)]> show variables like ‘%log_bin%‘;+---------------------------------+-------+| Variable_name                   | Value |+---------------------------------+-------+| log_bin                         | OFF   | --该参数用于设定是否启用二进制日志| log_bin_trust_function_creators | OFF   || sql_log_bin                     | ON    |+---------------------------------+-------+--以下为binary log相关参数root@localhost[(none)]> show variables like ‘%binlog%‘;+-----------------------------------------+----------------------+| Variable_name                           | Value                |+-----------------------------------------+----------------------+| binlog_cache_size                       | 32768                || binlog_direct_non_transactional_updates | OFF                  || binlog_format                           | STATEMENT            || binlog_stmt_cache_size                  | 32768                || innodb_locks_unsafe_for_binlog          | OFF                  || max_binlog_cache_size                   | 18446744073709547520 || max_binlog_size                         | 1073741824           || max_binlog_stmt_cache_size              | 18446744073709547520 || sync_binlog                             | 0                    |+-----------------------------------------+----------------------+--当前mysql服务器数据文件的缺省位置root@localhost[(none)]> show variables like ‘%datadir%‘;+---------------+-----------------+| Variable_name | Value           |+---------------+-----------------+| datadir       | /var/lib/mysql/ |+---------------+-----------------+--停止mysql服务器suse11b:~ # service mysql stopShutting down MySQL....                                               done--编辑my.cnf来设定binary log日志位置(注，配置二进制日志路径及文件名后，系统变量log_bin被自动置为on)suse11b:~ # vi /etc/my.cnfsuse11b:~ # grep -v ^# /etc/my.cnf[mysqld]log-error=/tmp/suse11b.errlog_bin=/var/lib/mysql/binarylog/binlogsuse11b:~ # mkdir -p /var/lib/mysql/binarylogsuse11b:~ # chown -R mysql:mysql /var/lib/mysql/binarylogsuse11b:~ # /etc/init.d/mysql startStarting MySQL..                                                      donesuse11b:~ # ls -hltr /var/lib/mysql/binarylog/*-rw-rw---- 1 mysql mysql  39 Oct  3 13:41 /var/lib/mysql/binarylog/binlog.index  #索引文件-rw-rw---- 1 mysql mysql 107 Oct  3 13:41 /var/lib/mysql/binarylog/binlog.000001 #日志文件b、切换日志suse11b:~ # mysql -uroot -pxxxroot@localhost[(none)]> flush logs;Query OK, 0 rows affected (0.04 sec)root@localhost[(none)]> system ls -hltr /var/lib/mysql/binarylog/*-rw-rw---- 1 mysql mysql  78 Oct  3 13:43 /var/lib/mysql/binarylog/binlog.index-rw-rw---- 1 mysql mysql 107 Oct  3 13:43 /var/lib/mysql/binarylog/binlog.000002  #切换后产生了000002-rw-rw---- 1 mysql mysql 147 Oct  3 13:43 /var/lib/mysql/binarylog/binlog.000001root@localhost[(none)]> system mysqladmin flush-logs    #使用mysqladmin命令行工具flush-logs方式切换日志root@localhost[(none)]> system ls -hltr /var/lib/mysql/binarylog/*-rw-rw---- 1 mysql mysql 147 Oct  3 13:43 /var/lib/mysql/binarylog/binlog.000001-rw-rw---- 1 mysql mysql 117 Oct  3 13:45 /var/lib/mysql/binarylog/binlog.index-rw-rw---- 1 mysql mysql 107 Oct  3 13:45 /var/lib/mysql/binarylog/binlog.000003  #切换后产生了000003-rw-rw---- 1 mysql mysql 147 Oct  3 13:45 /var/lib/mysql/binarylog/binlog.000002root@localhost[(none)]> system mysqladmin refresh       #使用mysqladmin命令行工具refresh方式切换日志root@localhost[(none)]> system ls -hltr /var/lib/mysql/binarylog/*-rw-rw---- 1 mysql mysql 147 Oct  3 13:43 /var/lib/mysql/binarylog/binlog.000001-rw-rw---- 1 mysql mysql 147 Oct  3 13:45 /var/lib/mysql/binarylog/binlog.000002-rw-rw---- 1 mysql mysql 156 Oct  3 13:46 /var/lib/mysql/binarylog/binlog.index-rw-rw---- 1 mysql mysql 107 Oct  3 13:46 /var/lib/mysql/binarylog/binlog.000004  #切换后产生了000004-rw-rw---- 1 mysql mysql 147 Oct  3 13:46 /var/lib/mysql/binarylog/binlog.000003 c、模拟产生二进制日志及查看内容root@localhost[(none)]> create database tempdb;Query OK, 1 row affected (0.00 sec)root@localhost[(none)]> use tempdbDatabase changedroot@localhost[tempdb]> create table tb1(id smallint,val varchar(10));Query OK, 0 rows affected (0.00 sec)root@localhost[tempdb]> insert into tb1 values(1,‘jack‘);Query OK, 1 row affected (0.01 sec)root@localhost[tempdb]> system strings /var/lib/mysql/binarylog/binlog.000004bin?8.T5.5.39-logz=.Ttempdbcreate database tempdbtempdbcreate table tb1(id smallint,val varchar(10))tempdbBEGINtempdbinsert into tb1 values(1,‘jack‘)root@localhost[tempdb]> system more /var/lib/mysql/binarylog/binlog.index/var/lib/mysql/binarylog/binlog.000001/var/lib/mysql/binarylog/binlog.000002/var/lib/mysql/binarylog/binlog.000003/var/lib/mysql/binarylog/binlog.000004--使用命令行工具mysqlbinlog直接提取二进制日志的内容root@localhost[tempdb]> system mysqlbinlog /var/lib/mysql/binarylog/binlog.000004/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;/*!40019 SET @@session.max_insert_delayed_threads=0*/;/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;DELIMITER /*!*/;# at 4#141003 13:46:39 server id 1  end_log_pos 107   Start: binlog v 4, server v 5.5.39-log created 141003 13:46:39# Warning: this binlog is either in use or was not closed properly.BINLOG ‘PzguVA8BAAAAZwAAAGsAAAABAAQANS41LjM5LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEzgNAAgAEgAEBAQEEgAAVAAEGggAAAAICAgCAA==‘/*!*/;# at 107#141003 14:08:58 server id 1  end_log_pos 194   Query   thread_id=1     exec_time=0     error_code=0SET TIMESTAMP=1412316538/*!*/;SET @@session.pseudo_thread_id=1/*!*/;SET @@session.foreign_key_checks=1, @@session.sql_auto_is_null=0, @@session.unique_checks=1, @@session.autocommit=1/*!*/;SET @@session.sql_mode=0/*!*/;SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;/*!\C utf8 *//*!*/;SET @@session.character_set_client=33,@@session.collation_connection=33,@@session.collation_server=8/*!*/;SET @@session.lc_time_names=0/*!*/;SET @@session.collation_database=DEFAULT/*!*/;create database tempdb/*!*/;# at 194#141003 14:09:36 server id 1  end_log_pos 304   Query   thread_id=1     exec_time=0     error_code=0use `tempdb`/*!*/;SET TIMESTAMP=1412316576/*!*/;create table tb1(id smallint,val varchar(10))/*!*/;# at 304#141003 14:09:56 server id 1  end_log_pos 374   Query   thread_id=1     exec_time=0     error_code=0SET TIMESTAMP=1412316596/*!*/;BEGIN/*!*/;# at 374#141003 14:09:56 server id 1  end_log_pos 471   Query   thread_id=1     exec_time=0     error_code=0SET TIMESTAMP=1412316596/*!*/;insert into tb1 values(1,‘jack‘)/*!*/;# at 471#141003 14:09:56 server id 1  end_log_pos 498   Xid = 25COMMIT/*!*/;DELIMITER ;# End of log fileROLLBACK /* added by mysqlbinlog */;/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;--从以上的内容可以看出二进制日志记录了所有操作的DML语句及其开销，以及一些系统环境变量的信息。d、管理二进制日志--对于二进制日志，应尽可能保存在安全的位置，与数据分开存储  --使用show binary logs获取二进制日志相关信息root@localhost[(none)]> help show binary logs;Name: ‘SHOW BINARY LOGS‘Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [HELP PURGE BINARY LOGS], that showshow to determine which logs can be purged.root@localhost[tempdb]> show binary logs;+---------------+-----------+| Log_name      | File_size |+---------------+-----------+| binlog.000001 |       147 || binlog.000002 |       147 || binlog.000003 |       147 || binlog.000004 |       498 |+---------------+-----------+show binlog events用于在二进制日志中显示事件。如果未指定‘log_name‘，则显示第一个二进制日志。root@localhost[(none)]> help show binlog events;  --获取帮助信息Name: ‘SHOW BINLOG EVENTS‘Description:Syntax:SHOW BINLOG EVENTS   [IN ‘log_name‘] [FROM pos] [LIMIT [offset,] row_count]Shows the events in the binary log. If you do not specify ‘log_name‘,the first binary log is displayed.root@localhost[(none)]> show binlog events;+---------------+-----+-------------+-----------+-------------+---------------------------------------+| Log_name      | Pos | Event_type  | Server_id | End_log_pos | Info                                  |+---------------+-----+-------------+-----------+-------------+---------------------------------------+| binlog.000001 |   4 | Format_desc |         1 |         107 | Server ver: 5.5.39-log, Binlog ver: 4 || binlog.000001 | 107 | Rotate      |         1 |         147 | binlog.000002;pos=4                   |+---------------+-----+-------------+-----------+-------------+---------------------------------------+root@localhost[(none)]> show binlog events in ‘binlog.000005‘;  --binlog.000005不存在，所以报错ERROR 1220 (HY000): Error when executing command SHOW BINLOG EVENTS: Could not find target log--下面的这个查询中，前面执行的DML在这里均可以看到root@localhost[tempdb]> show binlog events in ‘binlog.000004‘;+---------------+-----+-------------+-----------+-------------+-------------------------------------------------------------+| Log_name      | Pos | Event_type  | Server_id | End_log_pos | Info                                                        |+---------------+-----+-------------+-----------+-------------+-------------------------------------------------------------+| binlog.000004 |   4 | Format_desc |         1 |         107 | Server ver: 5.5.39-log, Binlog ver: 4                       || binlog.000004 | 107 | Query       |         1 |         194 | create database tempdb                                      || binlog.000004 | 194 | Query       |         1 |         304 | use `tempdb`; create table tb1(id smallint,val varchar(10)) || binlog.000004 | 304 | Query       |         1 |         374 | BEGIN                                                       || binlog.000004 | 374 | Query       |         1 |         471 | use `tempdb`; insert into tb1 values(1,‘jack‘)              || binlog.000004 | 471 | Xid         |         1 |         498 | COMMIT /* xid=25 */                                         |+---------------+-----+-------------+-----------+-------------+-------------------------------------------------------------+root@localhost[tempdb]> show binlog events in ‘binlog.000004‘ from 374;+---------------+-----+------------+-----------+-------------+------------------------------------------------+| Log_name      | Pos | Event_type | Server_id | End_log_pos | Info                                           |+---------------+-----+------------+-----------+-------------+------------------------------------------------+| binlog.000004 | 374 | Query      |         1 |         471 | use `tempdb`; insert into tb1 values(1,‘jack‘) || binlog.000004 | 471 | Xid        |         1 |         498 | COMMIT /* xid=25 */                            |+---------------+-----+------------+-----------+-------------+------------------------------------------------+root@localhost[tempdb]> show binlog events in ‘binlog.000004‘ from 374 limit 1;+---------------+-----+------------+-----------+-------------+------------------------------------------------+| Log_name      | Pos | Event_type | Server_id | End_log_pos | Info                                           |+---------------+-----+------------+-----------+-------------+------------------------------------------------+| binlog.000004 | 374 | Query      |         1 |         471 | use `tempdb`; insert into tb1 values(1,‘jack‘) |+---------------+-----+------------+-----------+-------------+------------------------------------------------+d、删除历史日志--使用purge手动删除指定日志--使用expire-log-days删除失效日志，设置变量expire_logs_days，删除超出这个变量保留期之前的所有日志被删除--自动日志删除通常发生在服务器启动以及日志flush--reset master方式root@localhost[(none)]> help purge;Name: ‘PURGE BINARY LOGS‘Description:Syntax:PURGE { BINARY | MASTER } LOGS    { TO ‘log_name‘ | BEFORE datetime_expr }Examples:PURGE BINARY LOGS TO ‘mysql-bin.010‘;PURGE BINARY LOGS BEFORE ‘2008-04-02 22:46:26‘;root@localhost[tempdb]> purge binary logs to ‘binlog.000003‘;Query OK, 0 rows affected (0.12 sec)root@localhost[tempdb]> show binary logs;+---------------+-----------+| Log_name      | File_size |+---------------+-----------+| binlog.000003 |       147 || binlog.000004 |       498 |+---------------+-----------+root@localhost[tempdb]> system ls -hltr /var/lib/mysql/binarylog/*-rw-rw---- 1 mysql mysql 147 Oct  3 13:46 /var/lib/mysql/binarylog/binlog.000003-rw-rw---- 1 mysql mysql 498 Oct  3 14:09 /var/lib/mysql/binarylog/binlog.000004-rw-rw---- 1 mysql mysql  78 Oct  3 14:23 /var/lib/mysql/binarylog/binlog.index--使用before子句purge日志，binlog.000003被删除root@localhost[tempdb]> purge binary logs before ‘2014-10-03 14:09:56‘;Query OK, 0 rows affected (0.02 sec)root@localhost[tempdb]> show binary logs;+---------------+-----------+| Log_name      | File_size |+---------------+-----------+| binlog.000004 |       498 |+---------------+-----------+--Author: Leshami--Blog  : http://blog.csdn.net/leshami--重置所有日志--reset master将删除在索引文件中列出所有的日志文件并重置索引文件，最后生成一个新的binlog文件。--该操作之前先备份binlog至其它位置以备以后需要。root@localhost[tempdb]> help reset master;Name: ‘RESET MASTER‘Description:Syntax:RESET MASTERDeletes all binary log files listed in the index file, resets thebinary log index file to be empty, and creates a new binary log file.This statement is intended to be used only when the master is startedfor the first time.root@localhost[tempdb]> reset master;Query OK, 0 rows affected (0.13 sec)root@localhost[tempdb]> show binary logs;+---------------+-----------+| Log_name      | File_size |+---------------+-----------+| binlog.000001 |       107 |  --reset之后，从000001开始生成全新空日志+---------------+-----------+--expire_log系统变量控制二进制日志自动删除的天数。默认值为0,表示“没有自动删除”。启动时和二进制日志循环时可能删除。root@localhost[tempdb]> show variables like ‘expire_log%‘;+------------------+-------+| Variable_name    | Value |+------------------+-------+| expire_logs_days | 0     |+------------------+-------+root@localhost[tempdb]> set expire_logs_days=7;   --提示次系统变量为全局变量ERROR 1229 (HY000): Variable ‘expire_logs_days‘ is a GLOBAL variable and should be set with SET GLOBALroot@localhost[tempdb]> set global expire_logs_days=7;  --设置Query OK, 0 rows affected (0.01 sec)root@localhost[tempdb]> select @@expire_logs_days;+--------------------+| @@expire_logs_days |+--------------------+|                  7 |+--------------------+

MySQL 二进制日志(Binary Log)