MySQL二进制日志的主要作用有三个：数据恢复、主从服务器日志复制即同步、审计判断是否有对数据库进行注入的攻击。二进制日志文件无法直接打开，需要工具进行分析。
1、首先，启动二进制日志。参数是 log_bin，动态参数，所以需要在配置文件中设置如下。也可以直接”log_bin=“参数后面设置文件路径。查看路径的参数为datadir。
[root@localhost mysql]# cat /etc/my.cnf
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
log_bin
...
mysql> show variables like 'datadir';
+---------------+-----------------+
| Variable_name | Value |
+---------------+-----------------+
| datadir | /var/lib/mysql/ |
+---------------+-----------------+
1 row in set (0.00 sec)
mysql>
2、二进制日志文件列表如下，
[root@localhost mysql]# ll
-rw-rw---- 1 mysql mysql 215978 2月 28 15:30 localhost-bin.000001
-rw-rw---- 1 mysql mysql 120 2月 28 15:30 localhost-bin.000002
-rw-rw---- 1 mysql mysql 115 3月 2 13:33 localhost-bin.index
3、二进制日志的分析工具必须通过MySQL 自带的mysqlbinlog 工具。
例1、从最新的日志文件000002的开始看，这里没有任何的记录，只是记录了文件头信息。
[root@localhost mysql]# mysqlbinlog --start-position=0 localhost-bin.000002
Warning: option 'start-position': unsigned value 0 adjusted to 4
/*!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
#200228 15:30:30 server id 1 end_log_pos 120 CRC32 0xda43dea1 Start: binlog v 4, server v 5.6.27-log created 200228 15:30:30 at startup
# Warning: this binlog is either in use or was not closed properly.
ROLLBACK/*!*/;
BINLOG '
lsFYXg8BAAAAdAAAAHgAAAABAAQANS42LjI3LWxvZwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAACWwVheEzgNAAgAEgAEBAQEEgAAXAAEGggAAAAICAgCAAAACgoKGRkAAaHe
Q9o=
'/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
[root@localhost mysql]#
例2、最新的日志文件000002的Position 为120，而该文件长度刚刚120Bytes。
[root@localhost mysql]# mysql -uroot -p
...
mysql> show master status;
+----------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+----------------------+----------+--------------+------------------+-------------------+
| localhost-bin.000002 | 120 | | | |
+----------------------+----------+--------------+------------------+-------------------+
1 row in set (0.01 sec)
mysql>
...
例3、历史日志文件000001的Position 为215486开始 的信息如下。
[root@localhost mysql]# mysqlbinlog --start-position=215486 localhost-bin.000001
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
...
# at 215486
#200228 15:21:48 server id 1 end_log_pos 215585 CRC32 0x20df1851 Query thread_id=1 exec_time=0 error_code=0
SET TIMESTAMP=1582874508/*!*/;
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=1075838976/*!*/;
SET @@session.auto_increment_increment=1, @@session.auto_increment_offset=1/*!*/;
/*!C latin1 *//*!*/;
SET @@session.character_set_client=8,@@session.collation_connection=8,@@session.collation_server=33/*!*/;
SET @@session.lc_time_names=0/*!*/;
SET @@session.collation_database=DEFAULT/*!*/;
BEGIN
/*!*/;
# at 215585
...
# at 215955
#200228 15:30:27 server id 1 end_log_pos 215978 CRC32 0x8374e4e4 Stop
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
[root@localhost mysql]#
例4、将上述历史日志文件000001的Position +1变成215487开始得到的信息如下。
[root@localhost mysql]# mysqlbinlog --start-position=215487 localhost-bin.000001
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=1*/;
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
...
ERROR: Error in Log_event::read_log_event(): 'read error', data_len: 553648128, event_type: 1
ERROR: Could not read entry at offset 215487: Error in log format or read error.
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;
[root@localhost mysql]#
这里看到错误提示，因为215487不是一条记录的起始位置，所以start-position表示的是一条记录的在二进制文件中的物理起始位置。