Oracle SYS.AUDSES$ 序列 说明

一.S YS.AUDSES$ 序列说明

1.1 MOS 说明

MOS 文档：How Sessions get Their AUDSID Identifier [ID 122230.1] Sessions connecting to an Oracle database have a number of identifiersassigned to them which can be found in the V$SESSION dynamic view.

--当session 连接到Oracle 数据库时，会分配一个标识号，这个标识号可以从v$session这个视图里查询。

One of these identifiers is V$SESSION.AUDSID. This identifier is particularlyuseful because it can also be obtained by a session using the SQL functionUSERENV('SESSIONID'). In this way, a session can find its own session-related information.

--其中一个标识符就是v$session.audsid. 这个标识符非常有用，因为它也可以用SQL 函数USERENV(‘SESSIONID’) 来获取，这样，session 就可以发现其关联的信息。

1.2 SESSION 获取v$session.audsid说明

A session connected to an Oracle database may obtain one of its sessionidentifiers, the Auditing Session ID, by use of the built-in USERENV SQLfunction.

For example, in SQL*Plus, a query like the following can be used:

SQL> select userenv('SESSIONID') from dual;

USERENV('SESSIONID')

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

13591

--查看当前的Auditing session id

This value may be used to find out more information about the current sessionas it is also recorded in the column AUDSID of the V$SESSION dynamic view.

--通过这个audid，然后和v$session结合，就可以查看session 的更多信息。Continuing the previous example:

SQL> select sid,serial#,audsid,program from v$session where audsid=13591;

SID SERIAL# AUDSID PROGRAM

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

13 2904 13591 sqlplus@sunclient1 (TNS V1-V2)

This Auditing Session ID is determined when the user connects to the databaseand is a constant value for the duration of the session.

--AUDID 决定用户是什么时候连接到数据库的，在session 活动期间，该值是不变的。

The value that is assigned to AUDSID is taken from a sequence in the OracleData Dictionary, the sequence SYS.AUDSES$. When AUDSID is assigned to a newsession the SYS.AUDSES$ sequence is incremented using NEXTVAL and the newvalue is assigned to the session.

--那么session 分配的AUDSID 值是从SYS.AUDSES$序列中获取的，当分配时，SYS.AUDSES$会使用nextval增加，然后赋值给session。

However, not all sessions get an AUDSID: Sessions connecting as 'internal'do not increment the SYS.AUDSES$ sequence and the value of their AUDSID is 0.

--但是，不是所有的session 都可以获取到AUDSID值。用internal 连接时，就不会增加SYS.AUDSES$序列，其对应session 的AUDSID 值是0.

For example, see what happens when we connect internal in svrmgrl:

SVRMGR> connect internal

Connected.

SVRMGR> select userenv('SESSIONID') from dual;

USERENV('S

----------

1 row selected.

Connect internal gets an AUDSID of 0 irrespective of which tool was used.

--不管使用什么工具连接，只要用的是internal用户，那么AUDSID 就是0

For example, connecting internal from SQL*Plus:

SQL> connect internal/oracle

Connected.

SQL> select userenv('SESSIONID') from dual;

USERENV('SESSIONID')

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

Background processes also have 0 as their AUDSID value。