How to find out if you're accessing a RAC database

How can you tell if you're accessing a RAC database? Simple!

You can tell if it is a cluster database by looking to see if the cluster database parameter is set:-

SQL> select name, value from v$parameter where name='cluster_database';

NAME VALUE
--------------------- ---------------------
cluster_database TRUE


or


set serveroutput on
BEGIN
IF dbms_utility.is_cluster_database THEN
dbms_output.put_line('Running in SHARED/RAC mode.');
ELSE
dbms_output.put_line('Running in EXCLUSIVE mode.');
END IF;
END;
/

You can tell how many instances are active by:-

SQL> SELECT * FROM V$ACTIVE_INSTANCES;

INST_NUMBER INST_NAME
----------- -----------------------

1 c1718-6-45:AXIOSS1

2 c1718-6-46:AXIOSS2