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MySQL中二進制日志binlog中的事件類型
MySQL binlog記錄的所有操作實際上都有對應的事件類型的，譬如STATEMENT格式中的DML操作對應的是QUERY_EVENT類型，ROW格式下的DML操作對應的是ROWS_EVENT類型。
首先，看看源碼中定義的事件類型
源碼位置：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 */
};
實際上還是蠻多的，下面就挑幾個重點的說一下
QUERY_EVENT
QUERY_EVENT以文本的形式來記錄事務的操作。
QUERY_EVENT類型的事件通常在以下幾種情況下使用：
1. 事務開始時，執行的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中為了取代之前版本中的START_EVENT_V3事件而引入的。它是binlog文件中的第一個事件，而且，該事件只會在binlog中出現一次。MySQL根據FORMAT_DESCRIPTION_EVENT的定義來解析其它事件。
它通常指定了MySQL Server的版本，binlog的版本，該binlog文件的創建時間。
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
對於ROW格式的binlog，所有的DML語句都是記錄在ROWS_EVENT中。
ROWS_EVENT分為三種：WRITE_ROWS_EVENT，UPDATE_ROWS_EVENT，DELETE_ROWS_EVENT，分別對應insert，update和delete操作。
對於insert操作，WRITE_ROWS_EVENT包含了要插入的數據
對於update操作，UPDATE_ROWS_EVENT不僅包含了修改後的數據，還包含了修改前的值。
對於delete操作，僅僅需要指定刪除的主鍵（在沒有主鍵的情況下，會給定所有列）
對於QUERY_EVENT事件，是以文本形式記錄DML操作的。而對於ROWS_EVENT事件，並不是文本形式，所以在通過mysqlbinlog查看基於ROW格式的binlog時，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
在事務提交時，不管是STATEMENT還是ROW格式的binlog，都會在末尾添加一個XID_EVENT事件代表事務的結束。該事件記錄了該事務的ID，在MySQL進行崩潰恢復時，根據事務在binlog中的提交情況來決定是否提交存儲引擎中狀態為prepared的事務。
ROTATE_EVENT
當binlog文件的大小達到max_binlog_size的值或者執行flush logs命令時，binlog會發生切換，這個時候會在當前的binlog日志添加一個ROTATE_EVENT事件，用於指定下一個日志的名稱和位置。
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
在啟用GTID模式後，MySQL實際上為每個事務都分配了個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
開啟GTID模式後，每個binlog開頭都會有一個PREVIOUS_GTIDS_LOG_EVENT事件，它的值是上一個binlog的PREVIOUS_GTIDS_LOG_EVENT+GTID_LOG_EVENT，實際上，在數據庫重啟的時候，需要重新填充gtid_executed的值，該值即是最新一個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，這樣，在下一個日志，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
當MySQL數據庫停止時，會在當前的binlog末尾添加一個STOP_EVENT事件表示數據庫停止。
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
