MySQL binlog中的事件类型详解

mysql binlog记录的所有操作实际上都有对应的事件类型的，譬如statement格式中的dml操作对应的是query_event类型，row格式下的dml操作对应的是rows_event类型。

首先，看看源码中定义的事件类型

源码位置：mysql-5.7.14/libbinlogevents/include/binlog_event.h

enum log_event_type
{
/**
every time you update this enum (when you add a type), you have to
fix format_description_event::format_description_event().
*/
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 is like load_event except that it has a longer
sql_ex, allowing multibyte terminated by etc; both types share the
same class (load_event)
*/
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,
/**
the pre_ga event numbers were used for 5.1.0 to 5.1.15 and are
therefore obsolete.
*/
pre_ga_write_rows_event = 20,
pre_ga_update_rows_event = 21,
pre_ga_delete_rows_event = 22,
/**
the v1 event numbers are used from 5.1.16 until mysql-trunk-xx
*/
write_rows_event_v1 = 23,
update_rows_event_v1 = 24,
delete_rows_event_v1 = 25,
/**
something out of the ordinary happened on the master
*/
incident_event= 26,
/**
heartbeat event to be send by master at its idle time
to ensure master's online status to slave
*/
heartbeat_log_event= 27,
/**
in some situations, it is necessary to send over ignorable
data to the slave: data that a slave can handle in case there
is code for handling it, but which can be ignored if it is not
recognized.
*/
ignorable_log_event= 28,
rows_query_log_event= 29,
/** version 2 of the row events */
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,
transaction_context_event= 36,
view_change_event= 37,
/* prepared xa transaction terminal event similar to xid */
xa_prepare_log_event= 38,
/**
add new events here - right above this comment!
existing events (except enum_end_event) should never change their numbers
*/
enum_end_event /* end marker */
};

实际上还是蛮多的，下面就挑几个重点的说一下

query_event

query_event以文本的形式来记录事务的操作。

query_event类型的事件通常在以下几种情况下使用：

1. 事务开始时，执行的begin操作。

2. statement格式中的dml操作

3. row格式中的ddl操作

譬如：

mysql> show binlog events in 'mysql-bin.000021';
+------------------+-----+-------------+-----------+-------------+-----------------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+-------------+-----------+-------------+-----------------------------------------------+
| mysql-bin.000021 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000021 | 120 | query | 1 | 195 | begin |
| mysql-bin.000021 | 195 | query | 1 | 298 | insert into test.t1 values(1,'a') |
| mysql-bin.000021 | 298 | xid | 1 | 329 | commit /* xid=25 */ |
| mysql-bin.000021 | 329 | query | 1 | 408 | begin |
| mysql-bin.000021 | 408 | query | 1 | 515 | use `test`; insert into test.t1 values(2,'b') |
| mysql-bin.000021 | 515 | xid | 1 | 546 | commit /* xid=33 */ |
+------------------+-----+-------------+-----------+-------------+-----------------------------------------------+

format_description_event

format_description_event是binlog version 4中为了取代之前版本中的start_event_v3事件而引入的。它是binlog文件中的第一个事件，而且，该事件只会在binlog中出现一次。mysql根据format_description_event的定义来解析其它事件。

它通常指定了mysql server的版本，binlog的版本，该binlog文件的创建时间。

譬如：

# at 4
#160817 11:00:10 server id 1 end_log_pos 120 crc32 0x03010da1 start: binlog v 4, server v 5.6.31-log created 160817 11:00:10
# warning: this binlog is either in use or was not closed properly. 
mysql> show binlog events in 'mysql-bin.000021';
+------------------+-----+-------------+-----------+-------------+-----------------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+-------------+-----------+-------------+-----------------------------------------------+
| mysql-bin.000021 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
... 

rows_event

对于row格式的binlog，所有的dml语句都是记录在rows_event中。

rows_event分为三种：write_rows_event，update_rows_event，delete_rows_event，分别对应insert，update和delete操作。

对于insert操作，write_rows_event包含了要插入的数据

对于update操作，update_rows_event不仅包含了修改后的数据，还包含了修改前的值。

对于delete操作，仅仅需要指定删除的主键（在没有主键的情况下，会给定所有列）

对于query_event事件，是以文本形式记录dml操作的。而对于rows_event事件，并不是文本形式，所以在通过mysqlbinlog查看基于row格式的binlog时，需要指定-vv --base64-output=decode-rows。

譬如：

mysql> show binlog events in 'mysql-bin.000027';
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| mysql-bin.000027 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000027 | 120 | query | 1 | 188 | begin |
| mysql-bin.000027 | 188 | table_map | 1 | 236 | table_id: 80 (test.t1) |
| mysql-bin.000027 | 236 | write_rows | 1 | 278 | table_id: 80 flags: stmt_end_f |
| mysql-bin.000027 | 278 | xid | 1 | 309 | commit /* xid=198 */ |
| mysql-bin.000027 | 309 | query | 1 | 377 | begin |
| mysql-bin.000027 | 377 | table_map | 1 | 425 | table_id: 80 (test.t1) |
| mysql-bin.000027 | 425 | update_rows | 1 | 475 | table_id: 80 flags: stmt_end_f |
| mysql-bin.000027 | 475 | xid | 1 | 506 | commit /* xid=199 */ |
| mysql-bin.000027 | 506 | query | 1 | 574 | begin |
| mysql-bin.000027 | 574 | table_map | 1 | 622 | table_id: 80 (test.t1) |
| mysql-bin.000027 | 622 | delete_rows | 1 | 664 | table_id: 80 flags: stmt_end_f |
| mysql-bin.000027 | 664 | xid | 1 | 695 | commit /* xid=200 */ |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
13 rows in set (0.00 sec)

xid_event

在事务提交时，不管是statement还是row格式的binlog，都会在末尾添加一个xid_event事件代表事务的结束。该事件记录了该事务的id，在mysql进行崩溃恢复时，根据事务在binlog中的提交情况来决定是否提交存储引擎中状态为prepared的事务。

rotate_event

当binlog文件的大小达到max_binlog_size的值或者执行flush logs命令时，binlog会发生切换，这个时候会在当前的binlog日志添加一个rotate_event事件，用于指定下一个日志的名称和位置。

mysql> show binlog events in 'mysql-bin.000028';
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| mysql-bin.000028 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000028 | 120 | rotate | 1 | 167 | mysql-bin.000029;pos=4 |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
2 rows in set (0.00 sec)

# at 120
#160817 12:34:26 server id 1 end_log_pos 167 crc32 0xd965567c rotate to mysql-bin.000029 pos: 4 

gtid_log_event

在启用gtid模式后，mysql实际上为每个事务都分配了个gtid

譬如：

# at 448
#160818 5:37:32 server id 1 end_log_pos 496 crc32 0xaeb24aac gtid [commit=yes]
set @@session.gtid_next= 'cad449f2-5d4f-11e6-b353-000c29c64704:3'/*!*/;
# at 496
#160818 5:37:32 server id 1 end_log_pos 571 crc32 0x042ca092 query thread_id=2 exec_time=0 error_code=0
set timestamp=1471469852/*!*/;
begin
/*!*/;
# at 571
#160818 5:37:32 server id 1 end_log_pos 674 crc32 0xa35beb37 query thread_id=2 exec_time=0 error_code=0
set timestamp=1471469852/*!*/;
insert into test.t1 values(2,'b')
/*!*/;
# at 674
#160818 5:37:32 server id 1 end_log_pos 705 crc32 0x1905d8c6 xid = 12
commit/*!*/;

mysql> show binlog events in 'mysql-bin.000033';
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
| mysql-bin.000033 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000033 | 120 | previous_gtids | 1 | 191 | cad449f2-5d4f-11e6-b353-000c29c64704:1 |
| mysql-bin.000033 | 191 | gtid | 1 | 239 | set @@session.gtid_next= 'cad449f2-5d4f-11e6-b353-000c29c64704:2' |
| mysql-bin.000033 | 239 | query | 1 | 314 | begin |
| mysql-bin.000033 | 314 | query | 1 | 417 | insert into test.t1 values(1,'a') |
| mysql-bin.000033 | 417 | xid | 1 | 448 | commit /* xid=11 */ |
| mysql-bin.000033 | 448 | gtid | 1 | 496 | set @@session.gtid_next= 'cad449f2-5d4f-11e6-b353-000c29c64704:3' |
| mysql-bin.000033 | 496 | query | 1 | 571 | begin |
| mysql-bin.000033 | 571 | query | 1 | 674 | insert into test.t1 values(2,'b') |
| mysql-bin.000033 | 674 | xid | 1 | 705 | commit /* xid=12 */ |
| mysql-bin.000033 | 705 | rotate | 1 | 752 | mysql-bin.000034;pos=4 |
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
11 rows in set (0.00 sec)

previous_gtids_log_event

开启gtid模式后，每个binlog开头都会有一个previous_gtids_log_event事件，它的值是上一个binlog的previous_gtids_log_event+gtid_log_event，实际上，在数据库重启的时候，需要重新填充gtid_executed的值，该值即是最新一个binlog的previous_gtids_log_event+gtid_log_event。

譬如：

mysql> show binlog events in 'mysql-bin.000033';
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
| mysql-bin.000033 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000033 | 120 | previous_gtids | 1 | 191 | cad449f2-5d4f-11e6-b353-000c29c64704:1 |
| mysql-bin.000033 | 191 | gtid | 1 | 239 | set @@session.gtid_next= 'cad449f2-5d4f-11e6-b353-000c29c64704:2' |
| mysql-bin.000033 | 239 | query | 1 | 314 | begin |
| mysql-bin.000033 | 314 | query | 1 | 417 | insert into test.t1 values(1,'a') |
| mysql-bin.000033 | 417 | xid | 1 | 448 | commit /* xid=11 */ |
| mysql-bin.000033 | 448 | gtid | 1 | 496 | set @@session.gtid_next= 'cad449f2-5d4f-11e6-b353-000c29c64704:3' |
| mysql-bin.000033 | 496 | query | 1 | 571 | begin |
| mysql-bin.000033 | 571 | query | 1 | 674 | insert into test.t1 values(2,'b') |
| mysql-bin.000033 | 674 | xid | 1 | 705 | commit /* xid=12 */ |
| mysql-bin.000033 | 705 | rotate | 1 | 752 | mysql-bin.000034;pos=4 |
+------------------+-----+----------------+-----------+-------------+-------------------------------------------------------------------+
11 rows in set (0.00 sec)

mysql> show binlog events in 'mysql-bin.000034';
+------------------+-----+----------------+-----------+-------------+------------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+----------------+-----------+-------------+------------------------------------------+
| mysql-bin.000034 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000034 | 120 | previous_gtids | 1 | 191 | cad449f2-5d4f-11e6-b353-000c29c64704:1-3 |
+------------------+-----+----------------+-----------+-------------+------------------------------------------+
2 rows in set (0.00 sec)

mysql-bin.000033日志中的previous_gtids是cad449f2-5d4f-11e6-b353-000c29c64704:1，gtid是cad449f2-5d4f-11e6-b353-000c29c64704:2和cad449f2-5d4f-11e6-b353-000c29c64704:3，这样，在下一个日志，即mysql-bin.000034中的previous_gtids是cad449f2-5d4f-11e6-b353-000c29c64704:1-3。

# at 120
#160818 5:39:38 server id 1 end_log_pos 191 crc32 0x4e84f3b5 previous-gtids
# cad449f2-5d4f-11e6-b353-000c29c64704:1-3 

stop_event

当mysql数据库停止时，会在当前的binlog末尾添加一个stop_event事件表示数据库停止。

譬如：

mysql> show binlog events in 'mysql-bin.000030';
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| log_name | pos | event_type | server_id | end_log_pos | info |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
| mysql-bin.000030 | 4 | format_desc | 1 | 120 | server ver: 5.6.31-log, binlog ver: 4 |
| mysql-bin.000030 | 120 | stop | 1 | 143 | |
+------------------+-----+-------------+-----------+-------------+---------------------------------------+
2 rows in set (0.04 sec)

# at 120
#160818 5:18:04 server id 1 end_log_pos 143 crc32 0xf20ddc85 stop

以上所述是小编给大家介绍的mysql binlog中的事件类型详解，希望对大家有所帮助