Since the introduction of Oracle RAC, we have seen the additional system dictionary views of GV$ which reflect information across the various nodes of a RAC system. Unlike the V$ views of the data dictionary, which relate to the current status of the single node you are connected to, the GV$ allows you to see status throughout the system. In this article we will show how to view sessions through the entire system instead of just a single node.

1. Connect to NODE1 of your Oracle RAC system as a DBA users, in this example we connect as the user ljcatt..

mylinux>$ sqlplus ljcatt/ljcatt

SQL>

2. Connect to NODE2 of your Oracle RAC as sysdba.

mylinux>$ sqlplus ‘/ as sysdba’

SQL>

3. Use the SQL statement “select distinct(username) from v$session;” to view the current connections within NODE2 of your RAC. NOTE: You will not be able to see the connection from LJCATT in this dictionary view, because it only reflects connections to NODE2 and not the entire RAC.

SQL> select distinct(username) from v$session;

SYS

4. Wile still connected to NODE2 as sysdba, use the SQL statement “select distinct(username) from gv$session;” to view all sessions within the RAC. NOTE: Now you can see the connection to LJCATT.

SQL> select distinct(username) from gv$session;

SQL>

5. The GV$ dictionary views have the additional INST_ID column which give the node that the action is occurring in. Use the SQL statement “select inst_id from gv$session where username=’LJCATT’” to identify the NODE which LJCATT is currently connected to.

SQL> Select inst_id from gv$session where username=’LJCATT’;

SQL>

The lesson learned, when you are administrating a RAC system use the dictionary views of GV$ and not V$.

Larry J. Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com