1. exec_time 到底表示什么时间？

MySQL binlog日志解析后，我们能看到会有 exec_time= ，从字面意思理解这个记录的是执行时间，那这个记录的到底是单条sql的执行时间？还是事务的执行时间？下面通过测试来解读一下！

2.创建测试库表

mysql> create database test_shao;
Query OK, 1 row affected (0.03 sec)
mysql> use test_shao;
Database changed
mysql> create table test_1(id int not null auto_increment,primary key(id)) engine=innodb default charset=utf8mb4;
Query OK, 0 rows affected (0.03 sec)

3.RC隔离级别下 事务测试

3.1 RC 隔离级别下主库执行事务

show variables like 'transaction_isolation';
+-----------------------+----------------+
| Variable_name         | Value          |
+-----------------------+----------------+
| transaction_isolation | READ-COMMITTED |
+-----------------------+----------------+

flush logs;
begin;
select count(*) from cmp_sys_1.message;
insert into test_1 select sleep(5);
select count(*) from cmp_sys_1.message;
insert into test_1 select sleep(10);
commit;


mysql> flush logs;
Query OK, 0 rows affected (0.02 sec)

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> select count(*) from cmp_sys_1.message;

+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (45.24 sec)

mysql> 
mysql> insert into test_1 select sleep(5);
Query OK, 1 row affected (5.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> select count(*) from cmp_sys_1.message;
+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (35.73 sec)

mysql> insert into test_1 select sleep(10);
Query OK, 1 row affected (10.00 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

3.2 解析3.1操作生成的主库binlog

show master status;
+-----------------+-----------+--------------+------------------+----------------------------------------------+
| File            | Position  | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set                            |
+-----------------+-----------+--------------+------------------+----------------------------------------------+
| 3306-bin.000781 | 364155470 |              |                  | bc129ea5-5f01-11ed-ae48-fa163efcbfd5:1-17199 |
+-----------------+-----------+--------------+------------------+----------------------------------------------+
show variables like 'log_bin_basename';
+------------------+-----------------------------------+
| Variable_name    | Value                             |
+------------------+-----------------------------------+
| log_bin_basename | /app/mysql/mysql3306/log/3306-bin |
+------------------+-----------------------------------+

mysqlbinlog --base64-output=decode-rows -vvv  3306-bin.000781 >3306-bin.000781.txt

3.3 解析3.1操作生成的从库binlog

4.RR 隔离级别下，statment binlog格式下事务测试(从库还是row格式binlog)

#RC隔离级别下，binlog_format不允许使用statement格式

4.1 RR 隔离级别下主库不能使用statement 格式binlog

4.2 主库 RR 隔离级别+STATMENT binlog 格式下执行如下事务

4.3 解析4.2操作主库binlog日志(binlog_format=statement)

4.4 解析第6步从库隔离级别为RC,binlog_format=row

5.主库从库隔离级别都为RR，binlog_format=statement时事务测试

5.1 主库执行如下事务

mysql> use test_shao;
Database changed
mysql> set transaction_isolation='REPEATABLE-READ';
Query OK, 0 rows affected (0.00 sec)

mysql> set binlog_format='Statement';
Query OK, 0 rows affected (0.00 sec)

mysql> select * from test_1;
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
|  6 |
+----+
6 rows in set (0.00 sec)

mysql> flush logs;
Query OK, 0 rows affected (0.01 sec)

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> select count(*) from cmp_sys_1.message;

+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (29.95 sec)

mysql> 
mysql> insert into test_1 select sleep(4);
Query OK, 1 row affected, 1 warning (4.02 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> select count(*) from cmp_sys_1.message;
+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (24.32 sec)

mysql> insert into test_1 select sleep(8);
Query OK, 1 row affected, 1 warning (8.00 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

5.2解析5.1操作主库binlog日志(隔离级别RR，binlog_format=statement)

5.3解析5.1操作从库binlog日志(隔离级别RR，binlog_format=statement)

#对应的relaylog中记录的是statement格式的binlog

##从库记录的binlog格式依然为row格式是因为我只是设置了从库全局的隔离级别为RR，binlog_format=statement，但是我并没有重启从库io和sql线程。如果只是设置了从库的binlog_format=statement，主库binlog为row格式的话，从库复制会报如下错误

   LAST_ERROR_MESSAGE: Worker 1 failed executing transaction 'bc129ea5-5f01-11ed-ae48-fa163efcbfd5:17204' at master log 3306-bin.000785, end_log_pos 488; Error executing row event: 'Cannot execute statement: impossible to write to binary log since statement is in row format and BINLOG_FORMAT = STATEMENT.'

设置主库从库隔离级别为RR，binlog_format格式为statement重启复制线程后测试结果如下：

mysql> use test_shao;
Database changed
mysql> set transaction_isolation='REPEATABLE-READ';
Query OK, 0 rows affected (0.00 sec)

mysql> set binlog_format='Statement';
Query OK, 0 rows affected (0.00 sec)

mysql> flush logs;
Query OK, 0 rows affected (0.01 sec)

mysql> begin;
Query OK, 0 rows affected (0.00 sec)

mysql> select count(*) from cmp_sys_1.message;
+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (25.33 sec)

mysql> insert into test_1 select sleep(2);
Query OK, 1 row affected, 1 warning (2.03 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> select count(*) from cmp_sys_1.message;
+----------+
| count(*) |
+----------+
| 62882460 |
+----------+
1 row in set (20.08 sec)

mysql> insert into test_1 select sleep(4);
Query OK, 1 row affected, 1 warning (4.01 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> commit;
Query OK, 0 rows affected (0.00 sec)

主库binlog日志

从库binlog日志

#为什么从库binlog中第二个语句的exec_time时间为10s？？从库statement binlog格式下，exec_time 到底如何记录时间，有待继续研究