DBLE能否兼容设置隔离级别时不加session关键字

[gyshen5206]

• dble version：dble-3.21.10.0-97a3b6d73a49cb374020f930c59f82746220b424-20211119064810
• preconditions ：
  no
• configs：
  ** user.xml**

    <managerUser name="man1" password="654321" maxCon="100"/>
    <shardingUser name="sgy" password="admin" schemas="sbtest,testdb,tdb" readOnly="false"  maxCon="200"/>

• steps：
  step1.

[root@server_4 ~]#  mysql -usgy -padmin -h 10.186.65.4 -P 8066
mysql> \s
--------------
mysql  Ver 14.14 Distrib 5.7.25, for linux-glibc2.12 (x86_64) using  EditLine wrapper

Connection id:		3
Current database:	db_1
Current user:		[email protected]
SSL:			Not in use
Current pager:		stdout
Using outfile:		''
Using delimiter:	;
Server version:		5.7.11-dble-3.21.10.0-97a3b6d73a49cb374020f930c59f82746220b424-20211119064810 dble Server (ActionTech)
Protocol version:	10
Connection:		10.186.65.4 via TCP/IP
Server characterset:	utf8mb4
Db     characterset:	utf8mb4
Client characterset:	utf8
Conn.  characterset:	utf8
TCP port:		8066
--------------

• expect result：
  1.
• real result：
  1.

mysql> SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;    //不加session关键字，则执行报错,需要兼容
ERROR 1064 (HY000): setting transaction without any SESSION or GLOBAL keyword is not supported now
mysql> SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;   //添加session关键字后，可以正常运行
Query OK, 0 rows affected (0.00 sec)

需要帮忙兼容的原因是，通过.net框架生成的SQL为：SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;  暂未能添加session关键字

[PanternBao]

Use like this？

[gyshen5206]

mysql> \s

mysql Ver 14.14 Distrib 5.7.25, for linux-glibc2.12 (x86_64) using EditLine wrapper

Connection id: 6723
Current database:
Current user: sgy@localhost
SSL: Not in use
Current pager: stdout
Using outfile: ''
Using delimiter: ;
Server version: 5.7.25-log MySQL Community Server (GPL)
Protocol version: 10
Connection: Localhost via UNIX socket
Server characterset: utf8mb4
Db characterset: utf8mb4
Client characterset: utf8
Conn. characterset: utf8
UNIX socket: /data/mysql/data/3309/mysqld.sock
Uptime: 1 day 23 hours 11 min 36 sec

Threads: 29 Questions: 3513225 Slow queries: 110 Opens: 4800 Flush tables: 2 Open tables: 1600 Queries per second avg: 20.678

mysql> SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
Query OK, 0 rows affected (0.00 sec)

MySQL原生是支持设置事务隔离级别时不指定SESSION的写法，DBLE应该也支持。
DBLE为何允许不加session，主要影响是什么？

[PanternBao]

加session和不加session的语义是不一样的，具体可以参考：https://dev.mysql.com/doc/refman/8.0/en/set-transaction.html

在分布式的场景下，不加session的场景对于dble来说不易处理，因此，dble对不加session的场景是禁止的。

[gyshen5206]

好的，谢谢！