一網友反饋使用mysqlbinlog解析出的二進制日志中的內容中，有些SQL語句有#注釋的情況，這個是怎么回事呢？我們通過實驗來了解一下具體細節(jié)情況，如下所示，實驗環(huán)境為5.6.20-enterprise-commercial-advanced-log

# whereis mysqlbinlog

mysqlbinlog: /usr/bin/mysqlbinlog /usr/share/man/man1/mysqlbinlog.1.gz

我們先在參數(shù)文件my.cnf里面設置binlog_format=ROW ，然后重啟一下MySQL服務

mysql> show variables like 'binlog_format';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| binlog_format | ROW   |
+---------------+-------+
1 row in set (0.00 sec)
 
mysql> show master status;
+----------------------+----------+--------------+------------------+-------------------+
| File                 | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+----------------------+----------+--------------+------------------+-------------------+
| DB-Server-bin.000005 |      512 |              |                  |                   |
+----------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
 
mysql> 
 
 
 
mysql> drop table kkk;
Query OK, 0 rows affected (0.01 sec)
 
mysql> create table kkk (id int ,name varchar(32));
Query OK, 0 rows affected (0.02 sec)
 
mysql> insert into kkk
    -> select 100, 'name' union all
    -> select 200, 'kerry' union all
    -> select 300, 'k3';
Query OK, 3 rows affected (0.02 sec)
Records: 3  Duplicates: 0  Warnings: 0
 
mysql>

默認情況下只能看到一些經過base-64編碼的信息，如下所示：

[root@DB-Server ~]# /usr/bin/mysqlbinlog??/data/mysql/DB-Server-bin.000005

use `MyDB`/*!*/;
SET TIMESTAMP=1530288296/*!*/;
DROP TABLE `kkk` /* generated by server */
/*!*/;
# at 628
#180629 12:05:14 server id 1  end_log_pos 745 CRC32 0xc6037a3f  Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=1530288314/*!*/;
create table kkk (id int ,name varchar(32))
/*!*/;
# at 745
#180629 12:06:07 server id 1  end_log_pos 817 CRC32 0x74fd4efb  Query   thread_id=3     exec_time=0     error_code=0
SET TIMESTAMP=1530288367/*!*/;
BEGIN
/*!*/;
# at 817
#180629 12:06:07 server id 1  end_log_pos 866 CRC32 0xfb1391dd  Table_map: `MyDB`.`kkk` mapped to number 73
# at 866
#180629 12:06:07 server id 1  end_log_pos 930 CRC32 0xecb4e812  Write_rows: table id 73 flags: STMT_END_F
 
BINLOG '
71g2WxMBAAAAMQAAAGIDAAAAAEkAAAAAAAEABE15REIAA2trawACAw8CYAAD3ZET+w==
71g2Wx4BAAAAQAAAAKIDAAAAAEkAAAAAAAEAAgAC//xkAAAABG5hbWX8yAAAAAVrZXJyefwsAQAA
AmszEui07A==
'/*!*/;
# at 930
#180629 12:06:07 server id 1  end_log_pos 961 CRC32 0x7ca988e3  Xid = 37
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
/*!50530 SET @@SESSION.PSEUDO_SLAVE_MODE=0*/;

mysqlbinlog有一個參數(shù)–verbose(或-v)，將自動生成帶注釋的SQL語句（在行事件中重構偽SQL語句），其實這個并非原始SQL語句，而是偽SQL，如果使用這個參數(shù)兩次(如-v -v)，則輸出列的描述信息，會生成字段的類型、長度、是否為null等屬性信息：

-v, –verbose???????Reconstruct pseudo-SQL statements out of row events. -v??-v adds comments on column data types.

[root@DB-Server ~]# /usr/bin/mysqlbinlog -v /data/mysql/DB-Server-bin.000005

如上所示，其實這里的SQL語句不是原始SQL語句，那么能否看到原始SQL語句呢？答案是可以，但是必須設置系統(tǒng)變量binlog_rows_query_log_events

mysql> show variables like 'binlog_rows_query_log_events';
+------------------------------+-------+
| Variable_name                | Value |
+------------------------------+-------+
| binlog_rows_query_log_events | OFF   |
+------------------------------+-------+
1 row in set (0.00 sec)
 
mysql> set binlog_rows_query_log_events=1;
Query OK, 0 rows affected (0.00 sec)
 
mysql> flush logs;
Query OK, 0 rows affected (0.01 sec)
 
mysql>  show master status;
+----------------------+----------+--------------+------------------+-------------------+
| File                 | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+----------------------+----------+--------------+------------------+-------------------+
| DB-Server-bin.000026 |      120 |              |                  |                   |
+----------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
 
mysql>
mysql> insert into kkk select 600, 'k600';
Query OK, 1 row affected (0.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

[root@DB-Server ~]# /usr/bin/mysqlbinlog??–base64-output=DECODE-ROWS??-v -v /data/mysql/DB-Server-bin.000026

在二進制日志格式為MIXED模式下，簡單測試沒有發(fā)現(xiàn)SQL被注釋的情況，記錄的都是原始的SQL語句。不清楚是否存在某些特殊情況也會出現(xiàn)這種情況。網友反饋騰訊云的MySQL在MIXED模式下，也會出現(xiàn)這種情況，不過沒有使用過騰訊的MySQL，手頭也沒有測試環(huán)境，只能作罷！

標簽： Mysql

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