19C新特性--通过连接字符串以及触发器修改回话参数

根据业务需要，有些时候我们需要修改回话参数，但是应用代码无法进行修改，我们可以通过一下两种方式来进行修改

 

一:通过连接字符串--19c可行

 

1.通过字符串直接连接数据库

 

在19c上测试，这种方式是可行的，但是在11g上测试未果

[oracle@localhost ~]$ sqlplus dbmon/dbmon@"(DESCRIPTION=(CONNECT_DATA=(SESSION_SETTINGS=(optimizer_mode=first_rows_10)(statistics_level=all))(SERVER=DEDICATED)(SERVICE_NAME=ceshi))(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.56.30)(PORT=1521)))"

SQL*Plus: Release 19.0.0.0.0 - Production on Mon Aug 16 23:20:35 2021

Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle.  All rights reserved.

Last Successful login time: Mon Aug 16 2021 22:37:59 +08:00

Connected to:

Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

Version 19.3.0.0.0

 

 

SQL> show parameter optimizer_mode

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

optimizer_mode                       string      FIRST_ROWS_10

SQL> show parameter statistics_level

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

client_statistics_level              string      TYPICAL

statistics_level                     string      ALL

 

11g测试

[oracle@oracle11g ~]$ sqlplus dbmon/dbmon@"(DESCRIPTION=(CONNECT_DATA=(SESSION_SETTINGS=(optimizer_mode=first_rows_10)(statistics_level=all))(SERVER=DEDICATED)(SERVICE_NAME=orcl))(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.56.33)(PORT=1521)))"

SQL*Plus: Release 11.2.0.4.0 Production on Sun Aug 15 00:16:36 2021

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

 

 

SQL> show parameter optimizer_mode

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

optimizer_mode                       string      ALL_ROWS

SQL> show parameter statistics_level

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

statistics_level                     string      TYPICAL

 

 

2：通过连接字符串的方式连修改回话参数

 

下面这种方式不通过监听的方式连接数据库

pdbcs=

(DESCRIPTION=

  (ADDRESS_LIST=

   (ADDRESS=

    (PROTOCOL=BEQ)

    (PROGRAM=oracle)

    (ARGV0=oracleCDB1)

    (ARGS='(DESCRIPTION=(SILLY_EXAMPLE=TRUE)(LOCAL=YEP)(ADDRESS=(PROTOCOL=beq)))')

   )

  )

  (CONNECT_DATA=

   (SESSION_SETTINGS=(container=ceshi)(optimizer_mode=first_rows_10))

   (SERVICE_NAME = ceshi)

   (INSTANCE_NAME = orcl)

  )

)

 

 

下面方式通过监听连接数据库

pdbcs1 =

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.30)(PORT = 1521))

    )

    (CONNECT_DATA =

      (SESSION_SETTINGS=(container=ceshi)(optimizer_mode=first_rows_10))

      (SERVICE_NAME = ceshi)

      (INSTANCE_NAME = orcl)

    )

  )

 

这里不进行演示登录之后回话参数的变化。

 

二:通过触发器--11g可行

create or replace trigger dbmon.set_session_settings after logon on dbmon.schema

begin

  execute immediate 'alter session set optimizer_mode=first_rows_10';

end;

/

 

1.创建触发器

SQL> create or replace trigger dbmon.set_session_settings after logon on dbmon.schema

  2  begin

  3    execute immediate 'alter session set optimizer_mode=first_rows_10';

  4  end;

  5  /

Trigger created.

 

2.查看当前会话参数，并切换用户后再次查看回话参数

SQL> show parameter optimizer_mode

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

optimizer_mode                       string      ALL_ROWS

SQL> conn dbmon/dbmon

Connected.

SQL> show parameter optimizer_mode

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

optimizer_mode                       string      FIRST_ROWS_10