The name of the next binary log. The filename is not null-terminated. Its length is the event size minus the size of the fixed parts.

XID_EVENT：

为了事务的一致性，写binlog的时候，先写事务的语句，然后写xid标志，最后才是提交COMMIT命令。

Fixed part为空

variable part8bytes，记录的是xid编号

关于rotate event的例子：

master [localhost] {root} ((none)) > show binlog events in 'mysql-bin.000001';

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

| Log_name| Pos | Event_type| Server_id | End_log_pos | Info|

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

| mysql-bin.000001 |4 | Format_desc |1 |120 | Server ver: 5.6.37-log, Binlog ver: 4 |

| mysql-bin.000001 | 120 | Rotate|1 |167 | mysql-bin.000002;pos=4|

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

2 rows in set (0.00 sec)

[root@test_mysql26 /root/sandboxes/rsandbox_5_6_37/master/data ]# hexdump -C mysql-bin.000001-s 4 -n 19 导出format desc event的内容

00000004e2 e3 fe 59 0f 01 00 0000 74 00 00 00 78 00 00|...Y.....t...x..|

0000001400 00 00|...|

00000017

00 00最后2位都是0000表示这个binlog关闭了，如果是01 00表示这个binlog还在使用中。

[root@test_mysql26 /root/sandboxes/rsandbox_5_6_37/master/data ]# hexdump -C mysql-bin.000001 -s 120导出rotate event的内容

00000078f6 e3 fe 59 04 01 00 0000 2f 00 00 00 a7 00 00|...Y...../......|

0000008800 00 00 04 00 00 00 0000 00 00 6d 79 73 71 6c|...........mysql|

000000982d 62 69 6e 2e 30 30 3030 30 32 ce 7f 95 b8|-bin.000002....|

000000a7

event_header(19bytes)具体如下：

f6 e3 fe 59timestamp

04type_code其event type是0x04,表示是一个rotate event

01 00 00 00server_id表示serverid是 1

2f 00 00 00event_length长度为2f，十进制表示就是47bytes

a7 00 00 00next_position下一个event起始位置为0xa7，十进制表示就是167

00 00flags0000表示这个binlog已经正常关闭了

然后是event data部分，具体如下：

04 00 00 00 00 00 00 00Fixed data部分，8bytes,记录的是下一个binlog的位置偏移4

6d 79 73 71 6c 2d 62 69 6e 2e 30 30 30 30 30 32Variable data部分，记录的是下一个binlog的文件名mysql-bin.000002

ce 7f 95 b8含义未知

TABLE_MAP_EVENT：

Used for row-based binary logging beginning with MySQL 5.1.5.

Fixed data part:

6 bytes. The table ID.

2 bytes. Reserved for future use.

Variable data part:

1 byte. The length of the database name. 库名的长度

Variable-sized. The database name (null-terminated). 库名

1 byte. The length of the table name.表名的长度

Variable-sized. The table name (null-terminated). 表名

Packed integer. The number of columns in the table. 列的数量

Variable-sized. An array of column types, one byte per column. To find the meanings of these values, look atenum_field_typesin themysql_com.hheader file. 每一列的数据类型

Packed integer. The length of the metadata block.metadata block的长度

Variable-sized. The metadata block; see log_event.h for contents and format.

Variable-sized. Bit-field indicating whether each column can beNULL, one bit per column. For this field, the amount of storage required forNcolumns isINT((N+7)/8)bytes.该部分记录字段是否允许为空，一位代表一个字段，占用字int((N+7/8))bytes,N为字段数

WRITE_ROWS_EVENT、DELETE_ROW_EVENTS、UPDATE_ROW_EVENTS 都参考如下这种解释：

Used for row-based binary logging beginning with MySQL 5.1.18.

[TODO: following needs verification; it's guesswork]

Fixed data part:

6 bytes. The table ID.

2 bytes. Reserved for future use.

Variable data part:

Packed integer. The number of columns in the table. 列的数量

Variable-sized. Bit-field indicating whether each column is used, one bit per column. For this field, the amount of storage required forNcolumns isINT((N+7)/8)bytes.

Variable-sized (forUPDATE_ROWS_LOG_EVENTonly). Bit-field indicating whether each column is used in theUPDATE_ROWS_LOG_EVENTafter-image; one bit per column. For this field, the amount of storage required forNcolumns isINT((N+7)/8)bytes.

Variable-sized. A sequence of zero or more rows. The end is determined by the size of the event. Each row has the following format:

Variable-sized. Bit-field indicating whether each field in the row isNULL. Only columns that are "used" according to the second field in the variable data part are listed here. If the second field in the variable data part hasNone-bits, the amount of storage required for this field isINT((N+7)/8)bytes.

Variable-sized. The row-image, containing values of all table fields. This only lists table fields that are used (according to the second field of the variable data part) and non-NULL(according to the previous field). In other words, the number of values listed here is equal to the number of zero bits in the previous field (not counting padding bits in the last byte).
The format of each value is described in thelog_event_print_value()function inlog_event.cc.

(forUPDATE_ROWS_EVENTonly) the previous two fields are repeated, representing a second table row.

For each row, the following is done:

ForWRITE_ROWS_LOG_EVENT, the row described by the row-image is inserted.

ForDELETE_ROWS_LOG_EVENT, a row matching the given row-image is deleted.

ForUPDATE_ROWS_LOG_EVENT, a row matching the first row-image is removed, and the row described by the second row-image is inserted.

HEARTBEAT_LOG_EVENT：

AHeartbeat_log_eventis sent by a master to a slave to let the slave know that the master is still alive. Events of this type do not appear in the binary or relay logs. They are generated on a master server by the thread that dumps events and sent straight to the slave without ever being written to the binary log. The slave examines the event contents and then discards it without writing it to the relay log.

主从心跳的heartbeat event是不写到binlog里面的。Sent by a master to a slave to let the slave know that the master is still alive. Not written to log files.