写在前面

本文有点长, 不耐心的可以直接看总结.

说明

也可以使用gdb查看生成binlog过程的, 但是太复杂了... 还是看源码注释方便点.

本文主要介绍的binlog 4的格式,下面使用的均是binlog4的情况, 然后使用python解析该格式与mysqlbinlog做对比.

解析binlog的工具有: mysqlbinlog, binlog2sql, pymysqlreplication等.

下面的int类型未特殊说明均使用小端(little), 均为无符号

我的环境:

mysql 5.7.38-log

binlog_format = ROW

binlog_row_image = FULL

binlog_checksum = None #不影响,反正是最后4字节

可变长度计算方法:

本文例子均只考虑第一种情况. 主要是演示

第一个字段值	占用大小取值范围
0-250	1字节 0-250
252	2字节 251-0xffff
253	3字节 0xffff-0xffffff
254	8字节 0xffffff-0xfffffffffffffff

BINLOG文件格式

官网介绍binlog文件由开头的 4字节(0xFE 'bin’) 加上一些列的 event 组成.

第一个event是START_EVENT_V3或者FORMAT_DESCRIPTION_EVENT.

最后一个event是STOP_EVENT或者rROTATE_EVENT

所以我们着重看event组成即可.

BINLOG EVENT

binlog event组成

binlog event是由 event_header(固定19字节) 加上 event_body(由各事件决定大小)组成

| event header(19字节) | event body |

event_header

从左到右的字节为如下表内容

数据类型	名字	描述
int<4>	timestamp	时间戳
int<1>	event_type	event类型(5.7.38就有43种...)
int<4>	server-id	server_id
int<4>	event-size	event大小(含event_header的19字节)
int<4>	log-pos	下个event的起始地址(本event的结束地址)
int<2>	flags	flag

event_body

event_body由 post_header body crc32(可选,由变量binlog_checksum决定)组成

| post_header | body | crc32 |

不同的event的内容不一样, 下面讲下常用的event格式

binlog event分类

只列举部分.

管理类:

主要是控制识别binlog file的

START_EVENT_V3 第一个event
FORMAT_DESCRIPTION_EVENT 第一个event,替代start_event_v3的, 格式同start_event_v3
STOP_EVENT 最后一个event, 表示服务器已经停止运行(下次启动自动轮转)
ROTATE_EVENT 最有一个event, 服务器还在运行(自动轮转或者flush log)
SLAVE_EVENT
INCIDENT_EVENT
HEARTBEAT_EVENT

语句类:

QUERY_EVENT 存SQL的, 比如DDL
INTVAR_EVENT
RAND_EVENT
USER_VAR_EVENT
XID_EVENT 2pc提交的时候会写入这个event. 当作事务结束的标志

ROW格式类:

下面会讲这个的详细结构

TABLE_MAP_EVENT 每个row event前面都有个table_map_event记录表名和字段数据类型
DELETE_ROWS_EVENT 记录delete的
UPDATE_ROWS_EVENT 记录update的
WRITE_ROWS_EVENT 记录insert的

常见binlog event结构

FORMAT_DESCRIPTION_EVENT

每个Binlog文件的第一个event, 这个event记录如下数据

名字	大小(字节)	描述
binlog_version	int<2>	记录binlog版本的, 均为4
mysql_server_version	char<50>	记录mysql版本的, 不足的填充0
create_timestamp	int<4>	创建时间
event_header_length	int<1>	每个event的event_header的大小,固定值19
event_type_header_length	header的event_size减去上面的大小(19), 为数组类型, 每个记录值为1字节	每个event的event body的post header的大小

event_type_header_length 记录值参考(5.7.38-log) [56, 13, 0, 8, 0, 18, 0, 4, 4, 4, 4, 18, 0, 0, 95, 0, 4, 26, 8, 0, 0, 0, 8, 8, 8, 2, 0, 0, 0, 10, 10, 10, 42, 42, 0, 18, 52, 0, 1, 20, 121, 129, 83]

TABLE_MAP_EVENT

这个是row格式独有的, 记录下个row_event的表名,各字段类型.

除了开头8字节外(post_header)外, 均为可变长度....

名字	大小(字节)	描述
table_id	int<6>	表打开的id, 不是数据库里面的table_id
flags	2	保留字段
database_name_length	可变长度	数据库名长度
database_name	取决于database_name_length	数据库名(以0x00结尾, 这个字节不计算在database_name_length中)
table_name_length	可变长度	表名长度
table_name	取决于table_name_length	表名(以额外的0x00结尾, 就是不在table_name_length的计算中)
column_count	可变长度	多少个字段
column_type_list	取决于column_count	list类型, 每个字段的数据类型,用1字节表示(比如3表示int<4> 详情)
.....	.....	暂时用不上其它的

ROWS_EVENT

row_event 包含Delete_rows_log_event 和 Write_rows_log_event 和 Update_rows_log_event

继承关系如下图

Delete_rows_log_event 和 Write_rows_log_event 和 Update_rows_log_event 基本上一样, 都是继承自row_log_event

区别在于 Write_rows_log_event(insert) 没得Cols_before_image delete_rows_log_event没得Cols_after_image

 
         +-------------------------------------------------------+
         | Event Type | Cols_before_image | Cols_after_image     |
         +-------------------------------------------------------+
         |  DELETE    |   Deleted row     |    NULL              |
         |  INSERT    |   NULL            |    Inserted row      |
         |  UPDATE    |   Old     row     |    Updated row       |
         +-------------------------------------------------------+

结构如下

也是只有开头的8字节(post header)固定

名字	大小(字节)	描述
table_id	6
flags	2
width	可变长度	表有多少列
cols	INT((width + 7) / 8)	是否使用该列, 每列对于一个bit位, 对字节向上取整(数据读写只能按字节读写)
extra_row_info	Extra_row_info	暂不考虑, 以1字节算
columns_before_image	INT((width + 7) / 8)	仅update和delete有. 与binlog_row_image有关
columns_after_image	INT((width + 7) / 8)	仅update和insert有
Null_bit_mask	INT((width + 7) / 8)	某列是否为空, 每列对应一个比特位
row	table_map_event记录了大小	具体的数据(before_image + after_image), 如果还剩4字节的话, 就是CRC32校验. 每个image数据前面都有null_bit_mask

验证

生成测试数据

另起一个binlog 方便观察

 
(root@127.0.0.1) [(none)]> flush logs;
Query OK, 0 rows affected (0.01 sec)
 
(root@127.0.0.1) [(none)]> create table db1.t20230310(id int primary key, name varchar(20));
Query OK, 0 rows affected (0.01 sec)
 
(root@127.0.0.1) [(none)]> begin;
Query OK, 0 rows affected (0.00 sec)
 
(root@127.0.0.1) [(none)]> insert into db1.t20230310 values(1,'first'),(2,'ddcw');
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0
 
(root@127.0.0.1) [(none)]> delete from db1.t20230310 where id=1;
Query OK, 1 row affected (0.00 sec)
 
(root@127.0.0.1) [(none)]> update db1.t20230310 set name = 'ddcw update' where id=2;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
 
(root@127.0.0.1) [(none)]> commit;
Query OK, 0 rows affected (0.01 sec)
 
(root@127.0.0.1) [(none)]> show master status\G
*************************** 1. row ***************************
             File: m3308.001008
         Position: 1027
     Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: 6d650f1f-ba4e-11ed-99ab-000c2980c11e:1-29253,
7ab066ef-c1be-11ec-92dd-000c2980c11e:2579-2584:2700,
90bdfbb7-cbe2-11ec-a870-000c2980c112:25178542,
90bdfbb7-cbe2-11ec-a870-000c2980c11e:1-14138280:25178542,
aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-283382
1 row in set (0.00 sec)

hexdump解析

这个就是人工解析了, 只解析一部分. 重复的工作应该机器做

只解析第一个event吧...

 
12:23:55 [root@ddcw21 ~]#hexdump -C /data/mysql_3308/mysqllog/binlog/m3308.001008 
00000000  fe 62 69 6e 35 b0 0a 64  0f 6c 30 ad 18 77 00 00  |.bin5..d.l0..w..|
00000010  00 7b 00 00 00 01 00 04  00 35 2e 37 2e 33 38 2d  |.{.......5.7.38-|
00000020  6c 6f 67 00 00 00 00 00  00 00 00 00 00 00 00 00  |log.............|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 13  |................|
00000050  38 0d 00 08 00 12 00 04  04 04 04 12 00 00 5f 00  |8............._.|

前4个字节 fe 62 69 6e 查询ascii表得 '\xfebin' 和上面官方说的一致

再来看看第一个event, 前19字节是header, 不看了, 太多了. 从 4 + 19 字节看起走

注意是使用的小端

名字	二进制数据	ascii编码后
binlog_version	b'\x04\x00'	4
mysql_server_version	b'5.7.38-log\x00\x00' 为方便观察,去掉了后面的填充字段	5.7.38-log (去掉了填充字段)
create_timestamp	b'\x00\x00\x00\x00'	0
event_header_length	b'\x13'	19
event_type_header_length	b'8\r\x00\x08\x00 .... \x00m/Lp' 为方便观察省略了中间的数据	[56, 13, 0, 8, 0, 18, 0, 4, 4, 4, 4, 18, 0, 0, 95, 0, 4, 26, 8, 0, 0, 0, 8, 8, 8, 2, 0, 0, 0, 10, 10, 10, 42, 42, 0, 18, 52, 0, 1, 20, 121, 129, 83]

Python解析

人工解析确实太费劲了, 我们使用python来解析

脚本见文末. 此脚本未解析 row(需要TABLE_MAP_EVENT) 和 crc32

 
import row_event
aa = row_event.parse_event('/data/mysql_3308/mysqllog/binlog/m3308.001008',1000)
for x in aa:
	print(x)

每个row_event上面都有个TABLE_MAP_EVENT

我们人工解析下最后个update的row

数据 b'\xfc\x02\x00\x00\x00\x04ddcw\xfc\x02\x00\x00\x00\x0bddcw update'

类型 [3, 15] 查表得 3对应 int<4> 15对应varchar

未使用binlog crc32校验(mgr), 有的话, row的最后4字节就是crc32校验

 
>>> def btoint(bdata,t='little'):
...         return int.from_bytes(bdata,t)
... 
>>> aa = b'\xfc\x02\x00\x00\x00\x04ddcw\xfc\x02\x00\x00\x00\x0bddcw update'
>>> aa[0:1] #befor image null_bit_map
b'\xfc'
>>> btoint(aa[1:1+4]) #before image first column
2
>>> btoint(aa[5:6]) #查看varchar记录的长度, 仅考虑0-250(1字节的情况)
4
>>> aa[6:6+4] #before image seccond column
b'ddcw'
>>> 
>>> aa[10:11] #after image的 null_bit_map
b'\xfc'
>>> btoint(aa[11:15]) #after image的第一列 
2
>>> btoint(aa[15:16]) #after image的 第二列的长度
11
>>> aa[16:27]
b'ddcw update'
>>>

得到 Update前数据 (2,'ddcw') update后数据为(2,'ddcw update')

然后使用mysqlbinlog 解析对比一下, 发现对的上, 说明没有解析错

总结

1. binlog文件由开头固定4字节和各个event组成 (relay log也是)

2. 每个event由 header(固定19字节) 和 body组成, body又由post header 和 data组成(若剩余4字节就是crc32校验码)

3. 每个row_event前面都有个table_map_event记录表名,字段类型等信息.

4. 最后一个event如果是stop_event, 那就说明服务器停止了(下次启动字段切换), 如果是rota_event就说明文件切换了.

5. Delete_rows_log_event 和 Write_rows_log_event 和 Update_rows_log_event 都是继承自row_log_event, 区别在于 Write_rows_log_event(insert) 没得Cols_before_image

delete_rows_log_event没得Cols_after_image

附python代码

row_event.py

 
import binlog_event_type
import struct
def btoint(bdata,t='little'):
	return int.from_bytes(bdata,t)
 
def event_header(bdata):
	timestamp, event_type, server_id, event_size, log_pos, flags = struct.unpack("<LBLLLh",bdata[0:19])
	return {"timestamp":timestamp,'event_type':event_type,'server_id':server_id,'event_size':event_size,'log_pos':log_pos,'flags':flags,}
 
 
def first_event(bdata):
	#FORMAT_DESCRIPTION_EVENT
	ethl = len(bdata) - 57 #2 50 4 1 var
	ff = f'<h50sLB{ethl}s'
	binlog_version, mysql_server_version, create_timestamp, event_header_length, event_type_header_length = struct.unpack(ff,bdata)
	mysql_server_version = mysql_server_version.decode('ascii').replace('\x00','') #美化一下
	event_type_header_length = [ int(x) for x in event_type_header_length ] #event specific header length. 比如TABLE_MAP_EVENT = 8 (table_id:6 + flag:2) #记录其它event的post header的长度
	return {'binlog_version':binlog_version, 'mysql_server_version':mysql_server_version, 'create_timestamp':create_timestamp, 'event_header_length':event_header_length, 'event_type_header_length':event_type_header_length,}
 
def table_map_event(bdata):
	post_header = {'table_id':btoint(bdata[0:6]), 'flags':btoint(bdata[6:8])} #flags保留字段
	offset = 8
	database_length = btoint(bdata[offset:offset+1])
	offset +=1
	database_name = bdata[offset:offset+database_length].decode() #0x00 结尾
	offset += database_length + 1
	table_length = btoint(bdata[offset:offset+1])
	offset +=1
	table_name = bdata[offset:offset+table_length].decode() #0x00 结尾, 但是我不读,计数的时候别忘了就行
	offset += table_length + 1
	column_count = btoint(bdata[offset:offset+1]) #Packed Integer 我只考虑0-250个字段. 也就是占用1字节 计算方式https://dev.mysql.com/doc/dev/mysql-server/latest/classbinary__log_1_1Binary__log__event.html#packed_integer
	offset += 1
	column_type_list = []
	for x in range(column_count):
		column_type_list.append(btoint(bdata[offset:offset+1])) #先不做转换了.具体类型参考https://dev.mysql.com/doc/dev/mysql-server/latest/classbinary__log_1_1Table__map__event.html
		offset += 1
 
	#metadata_length和column_count一样, 但是我不想写了
	#省略 metadata_length metadata null_bits optional metadata fields
	return {
		'post_header':post_header,
		'body':{
			'database_name':database_name,
			'table_name':table_name,
			'column_type_list':column_type_list,
		}
		}
	
 
 
def row_event(bdata,imaget):
	#不解析具体的字段, 因为需要table_map才知道对应的字段类型
	#columns_before_image delete,update
	#columns_after_image  insert,update
	data = {}
	post_header = {'table_id':btoint(bdata[0:6]), 'flags':btoint(bdata[6:8])} #flags保留字段
	data['post_header'] = post_header
	data['body'] = {}
	offset = 8
	width = btoint(bdata[offset:offset+1])
	offset += 1
	_toff = int((width+7)/8)
	cols = btoint(bdata[offset:offset+_toff])
	offset += _toff
	extra_row_info = btoint(bdata[offset:offset+1])
	offset += 1
	if imaget == 30 or imaget == 31: #30 write   31 update   32 delete
		columns_after_image = btoint(bdata[offset:offset+_toff])
		offset += _toff
		data['body']['columns_after_image'] = columns_after_image
	if imaget == 32 or imaget == 31:
		columns_before_image = btoint(bdata[offset:offset+_toff])
		offset += _toff
		data['body']['columns_before_image'] = columns_before_image
	data['body']['row'] = bdata[offset:]
	data['body']['width'] = width
	data['body']['cols'] = cols
	data['body']['extra_row_info'] = extra_row_info
	return data
		
 
 
 
def parse_event(filename,n=10): #默认只解析前面10个event 
	data = []
	with open(filename,'rb') as f:
		magic = f.read(4)
		if magic != b'\xfebin':
			return False
		for x in range(n):
			event_data = None
			try:
				common_header = event_header(f.read(19))
			except:
				break
			event_bdata = f.read(common_header['event_size']-19)
			if common_header['event_type'] == binlog_event_type.FORMAT_DESCRIPTION_EVENT:
				event_data = first_event(event_bdata)
				common_header['event_type'] = 'FORMAT_DESCRIPTION_EVENT'
			elif common_header['event_type'] == binlog_event_type.WRITE_ROWS_EVENT:
				event_data = row_event(event_bdata,common_header['event_type'])
				common_header['event_type'] = 'WRITE_ROWS_EVENT'
			elif common_header['event_type'] == binlog_event_type.UPDATE_ROWS_EVENT:
				event_data = row_event(event_bdata,common_header['event_type'])
				common_header['event_type'] = 'UPDATE_ROWS_EVENT'
			elif common_header['event_type'] == binlog_event_type.DELETE_ROWS_EVENT:
				event_data = row_event(event_bdata,common_header['event_type'])
				common_header['event_type'] = 'DELETE_ROWS_EVENT'
			elif common_header['event_type'] == binlog_event_type.TABLE_MAP_EVENT:
				event_data = table_map_event(event_bdata)
				common_header['event_type'] = 'TABLE_MAP_EVENT'
			elif common_header['event_type'] == binlog_event_type.GTID_LOG_EVENT:
				common_header['event_type'] = 'GTID_LOG_EVENT'
			elif common_header['event_type'] == binlog_event_type.XID_EVENT:
				common_header['event_type'] = 'XID_EVENT'
			elif common_header['event_type'] == binlog_event_type.QUERY_EVENT:
				common_header['event_type'] = 'QUERY_EVENT'
				event_data = event_bdata
			elif common_header['event_type'] == binlog_event_type.STOP_EVENT:
				common_header['event_type'] = 'STOP_EVENT'
			elif common_header['event_type'] == binlog_event_type.PREVIOUS_GTIDS_LOG_EVENT:
				common_header['event_type'] = 'PREVIOUS_GTIDS_LOG_EVENT'
			elif common_header['event_type'] == binlog_event_type.ROTATE_EVENT:
				common_header['event_type'] = 'ROTATE_EVENT'
			data.append({'event_header':common_header,'event_body':event_data})
	return data

binlog_event_type.py

从源码 libbinlogevents/include/binlog_event.h 里面复制出来的

 
# -*- coding: utf-8 -*-
# libbinlogevents/include/binlog_event.h
UNKNOWN_EVENT= 0
START_EVENT_V3= 1
QUERY_EVENT= 2
STOP_EVENT= 3
ROTATE_EVENT= 4
INTVAR_EVENT= 5
LOAD_EVENT= 6
SLAVE_EVENT= 7
CREATE_FILE_EVENT= 8
APPEND_BLOCK_EVENT= 9
EXEC_LOAD_EVENT= 10
DELETE_FILE_EVENT= 11
NEW_LOAD_EVENT= 12
RAND_EVENT= 13
USER_VAR_EVENT= 14
FORMAT_DESCRIPTION_EVENT= 15
XID_EVENT= 16
BEGIN_LOAD_QUERY_EVENT= 17
EXECUTE_LOAD_QUERY_EVENT= 18
 
TABLE_MAP_EVENT = 19
 
PRE_GA_WRITE_ROWS_EVENT = 20
PRE_GA_UPDATE_ROWS_EVENT = 21
PRE_GA_DELETE_ROWS_EVENT = 22
 
WRITE_ROWS_EVENT_V1 = 23
UPDATE_ROWS_EVENT_V1 = 24
DELETE_ROWS_EVENT_V1 = 25
 
INCIDENT_EVENT= 26
 
HEARTBEAT_LOG_EVENT= 27
 
IGNORABLE_LOG_EVENT= 28
ROWS_QUERY_LOG_EVENT= 29
 
WRITE_ROWS_EVENT = 30
UPDATE_ROWS_EVENT = 31
DELETE_ROWS_EVENT = 32
 
GTID_LOG_EVENT= 33
ANONYMOUS_GTID_LOG_EVENT= 34
 
PREVIOUS_GTIDS_LOG_EVENT= 35 #描述之前的gtid信息(不需要扫描之前的binlog文件)
 
TRANSACTION_CONTEXT_EVENT= 36
 
VIEW_CHANGE_EVENT= 37
 
XA_PREPARE_LOG_EVENT= 38

	+-------------------------------------------------------+
	\| Event Type \| Cols_before_image \| Cols_after_image \|
	+-------------------------------------------------------+
	\| DELETE \| Deleted row \| NULL \|
	\| INSERT \| NULL \| Inserted row \|
	\| UPDATE \| Old row \| Updated row \|
	+-------------------------------------------------------+

	(root@127.0.0.1) [(none)]> flush logs;
	Query OK, 0 rows affected (0.01 sec)

	(root@127.0.0.1) [(none)]> create table db1.t20230310(id int primary key, name varchar(20));
	Query OK, 0 rows affected (0.01 sec)

	(root@127.0.0.1) [(none)]> begin;
	Query OK, 0 rows affected (0.00 sec)

	(root@127.0.0.1) [(none)]> insert into db1.t20230310 values(1,'first'),(2,'ddcw');
	Query OK, 2 rows affected (0.00 sec)
	Records: 2 Duplicates: 0 Warnings: 0

	(root@127.0.0.1) [(none)]> delete from db1.t20230310 where id=1;
	Query OK, 1 row affected (0.00 sec)

	(root@127.0.0.1) [(none)]> update db1.t20230310 set name = 'ddcw update' where id=2;
	Query OK, 1 row affected (0.00 sec)
	Rows matched: 1 Changed: 1 Warnings: 0

	(root@127.0.0.1) [(none)]> commit;
	Query OK, 0 rows affected (0.01 sec)

	(root@127.0.0.1) [(none)]> show master status\G
	************************* 1. row *************************
	File: m3308.001008
	Position: 1027
	Binlog_Do_DB:
	Binlog_Ignore_DB:
	Executed_Gtid_Set: 6d650f1f-ba4e-11ed-99ab-000c2980c11e:1-29253,
	7ab066ef-c1be-11ec-92dd-000c2980c11e:2579-2584:2700,
	90bdfbb7-cbe2-11ec-a870-000c2980c112:25178542,
	90bdfbb7-cbe2-11ec-a870-000c2980c11e:1-14138280:25178542,
	aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-283382
	1 row in set (0.00 sec)

	12:23:55 [root@ddcw21 ~]#hexdump -C /data/mysql_3308/mysqllog/binlog/m3308.001008
	00000000 fe 62 69 6e 35 b0 0a 64 0f 6c 30 ad 18 77 00 00 \|.bin5..d.l0..w..\|
	00000010 00 7b 00 00 00 01 00 04 00 35 2e 37 2e 33 38 2d \|.{.......5.7.38-\|
	00000020 6c 6f 67 00 00 00 00 00 00 00 00 00 00 00 00 00 \|log.............\|
	00000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 \|................\|
	00000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 13 \|................\|
	00000050 38 0d 00 08 00 12 00 04 04 04 04 12 00 00 5f 00 \|8............._.\|

	import row_event
	aa = row_event.parse_event('/data/mysql_3308/mysqllog/binlog/m3308.001008',1000)
	for x in aa:
	print(x)

	>>> def btoint(bdata,t='little'):
	... return int.from_bytes(bdata,t)
	...
	>>> aa = b'\xfc\x02\x00\x00\x00\x04ddcw\xfc\x02\x00\x00\x00\x0bddcw update'
	>>> aa[0:1] #befor image null_bit_map
	b'\xfc'
	>>> btoint(aa[1:1+4]) #before image first column
	2
	>>> btoint(aa[5:6]) #查看varchar记录的长度, 仅考虑0-250(1字节的情况)
	4
	>>> aa[6:6+4] #before image seccond column
	b'ddcw'
	>>>
	>>> aa[10:11] #after image的 null_bit_map
	b'\xfc'
	>>> btoint(aa[11:15]) #after image的第一列
	2
	>>> btoint(aa[15:16]) #after image的第二列的长度
	11
	>>> aa[16:27]
	b'ddcw update'
	>>>

	import binlog_event_type
	import struct
	def btoint(bdata,t='little'):
	return int.from_bytes(bdata,t)

	def event_header(bdata):
	timestamp, event_type, server_id, event_size, log_pos, flags = struct.unpack("<LBLLLh",bdata[0:19])
	return {"timestamp":timestamp,'event_type':event_type,'server_id':server_id,'event_size':event_size,'log_pos':log_pos,'flags':flags,}


	def first_event(bdata):
	#FORMAT_DESCRIPTION_EVENT
	ethl = len(bdata) - 57 #2 50 4 1 var
	ff = f'<h50sLB{ethl}s'
	binlog_version, mysql_server_version, create_timestamp, event_header_length, event_type_header_length = struct.unpack(ff,bdata)
	mysql_server_version = mysql_server_version.decode('ascii').replace('\x00','') #美化一下
	event_type_header_length = [ int(x) for x in event_type_header_length ] #event specific header length. 比如TABLE_MAP_EVENT = 8 (table_id:6 + flag:2) #记录其它event的post header的长度
	return {'binlog_version':binlog_version, 'mysql_server_version':mysql_server_version, 'create_timestamp':create_timestamp, 'event_header_length':event_header_length, 'event_type_header_length':event_type_header_length,}

	def table_map_event(bdata):
	post_header = {'table_id':btoint(bdata[0:6]), 'flags':btoint(bdata[6:8])} #flags保留字段
	offset = 8
	database_length = btoint(bdata[offset:offset+1])
	offset +=1
	database_name = bdata[offset:offset+database_length].decode() #0x00 结尾
	offset += database_length + 1
	table_length = btoint(bdata[offset:offset+1])
	offset +=1
	table_name = bdata[offset:offset+table_length].decode() #0x00 结尾, 但是我不读,计数的时候别忘了就行
	offset += table_length + 1
	column_count = btoint(bdata[offset:offset+1]) #Packed Integer 我只考虑0-250个字段. 也就是占用1字节计算方式https://dev.mysql.com/doc/dev/mysql-server/latest/classbinary__log_1_1Binary__log__event.html#packed_integer
	offset += 1
	column_type_list = []
	for x in range(column_count):
	column_type_list.append(btoint(bdata[offset:offset+1])) #先不做转换了.具体类型参考https://dev.mysql.com/doc/dev/mysql-server/latest/classbinary__log_1_1Table__map__event.html
	offset += 1

	#metadata_length和column_count一样, 但是我不想写了
	#省略 metadata_length metadata null_bits optional metadata fields
	return {
	'post_header':post_header,
	'body':{
	'database_name':database_name,
	'table_name':table_name,
	'column_type_list':column_type_list,
	}
	}



	def row_event(bdata,imaget):
	#不解析具体的字段, 因为需要table_map才知道对应的字段类型
	#columns_before_image delete,update
	#columns_after_image insert,update
	data = {}
	post_header = {'table_id':btoint(bdata[0:6]), 'flags':btoint(bdata[6:8])} #flags保留字段
	data['post_header'] = post_header
	data['body'] = {}
	offset = 8
	width = btoint(bdata[offset:offset+1])
	offset += 1
	_toff = int((width+7)/8)
	cols = btoint(bdata[offset:offset+_toff])
	offset += _toff
	extra_row_info = btoint(bdata[offset:offset+1])
	offset += 1
	if imaget == 30 or imaget == 31: #30 write 31 update 32 delete
	columns_after_image = btoint(bdata[offset:offset+_toff])
	offset += _toff
	data['body']['columns_after_image'] = columns_after_image
	if imaget == 32 or imaget == 31:
	columns_before_image = btoint(bdata[offset:offset+_toff])
	offset += _toff
	data['body']['columns_before_image'] = columns_before_image
	data['body']['row'] = bdata[offset:]
	data['body']['width'] = width
	data['body']['cols'] = cols
	data['body']['extra_row_info'] = extra_row_info
	return data




	def parse_event(filename,n=10): #默认只解析前面10个event
	data = []
	with open(filename,'rb') as f:
	magic = f.read(4)
	if magic != b'\xfebin':
	return False
	for x in range(n):
	event_data = None
	try:
	common_header = event_header(f.read(19))
	except:
	break
	event_bdata = f.read(common_header['event_size']-19)
	if common_header['event_type'] == binlog_event_type.FORMAT_DESCRIPTION_EVENT:
	event_data = first_event(event_bdata)
	common_header['event_type'] = 'FORMAT_DESCRIPTION_EVENT'
	elif common_header['event_type'] == binlog_event_type.WRITE_ROWS_EVENT:
	event_data = row_event(event_bdata,common_header['event_type'])
	common_header['event_type'] = 'WRITE_ROWS_EVENT'
	elif common_header['event_type'] == binlog_event_type.UPDATE_ROWS_EVENT:
	event_data = row_event(event_bdata,common_header['event_type'])
	common_header['event_type'] = 'UPDATE_ROWS_EVENT'
	elif common_header['event_type'] == binlog_event_type.DELETE_ROWS_EVENT:
	event_data = row_event(event_bdata,common_header['event_type'])
	common_header['event_type'] = 'DELETE_ROWS_EVENT'
	elif common_header['event_type'] == binlog_event_type.TABLE_MAP_EVENT:
	event_data = table_map_event(event_bdata)
	common_header['event_type'] = 'TABLE_MAP_EVENT'
	elif common_header['event_type'] == binlog_event_type.GTID_LOG_EVENT:
	common_header['event_type'] = 'GTID_LOG_EVENT'
	elif common_header['event_type'] == binlog_event_type.XID_EVENT:
	common_header['event_type'] = 'XID_EVENT'
	elif common_header['event_type'] == binlog_event_type.QUERY_EVENT:
	common_header['event_type'] = 'QUERY_EVENT'
	event_data = event_bdata
	elif common_header['event_type'] == binlog_event_type.STOP_EVENT:
	common_header['event_type'] = 'STOP_EVENT'
	elif common_header['event_type'] == binlog_event_type.PREVIOUS_GTIDS_LOG_EVENT:
	common_header['event_type'] = 'PREVIOUS_GTIDS_LOG_EVENT'
	elif common_header['event_type'] == binlog_event_type.ROTATE_EVENT:
	common_header['event_type'] = 'ROTATE_EVENT'
	data.append({'event_header':common_header,'event_body':event_data})
	return data

	# -- coding: utf-8 --
	# libbinlogevents/include/binlog_event.h
	UNKNOWN_EVENT= 0
	START_EVENT_V3= 1
	QUERY_EVENT= 2
	STOP_EVENT= 3
	ROTATE_EVENT= 4
	INTVAR_EVENT= 5
	LOAD_EVENT= 6
	SLAVE_EVENT= 7
	CREATE_FILE_EVENT= 8
	APPEND_BLOCK_EVENT= 9
	EXEC_LOAD_EVENT= 10
	DELETE_FILE_EVENT= 11
	NEW_LOAD_EVENT= 12
	RAND_EVENT= 13
	USER_VAR_EVENT= 14
	FORMAT_DESCRIPTION_EVENT= 15
	XID_EVENT= 16
	BEGIN_LOAD_QUERY_EVENT= 17
	EXECUTE_LOAD_QUERY_EVENT= 18

	TABLE_MAP_EVENT = 19

	PRE_GA_WRITE_ROWS_EVENT = 20
	PRE_GA_UPDATE_ROWS_EVENT = 21
	PRE_GA_DELETE_ROWS_EVENT = 22

	WRITE_ROWS_EVENT_V1 = 23
	UPDATE_ROWS_EVENT_V1 = 24
	DELETE_ROWS_EVENT_V1 = 25

	INCIDENT_EVENT= 26

	HEARTBEAT_LOG_EVENT= 27

	IGNORABLE_LOG_EVENT= 28
	ROWS_QUERY_LOG_EVENT= 29

	WRITE_ROWS_EVENT = 30
	UPDATE_ROWS_EVENT = 31
	DELETE_ROWS_EVENT = 32

	GTID_LOG_EVENT= 33
	ANONYMOUS_GTID_LOG_EVENT= 34

	PREVIOUS_GTIDS_LOG_EVENT= 35 #描述之前的gtid信息(不需要扫描之前的binlog文件)

	TRANSACTION_CONTEXT_EVENT= 36

	VIEW_CHANGE_EVENT= 37

	XA_PREPARE_LOG_EVENT= 38

MYSQL BINLOG文件解析