This blog is about my first installation of Oracle 12c(18.104.22.168.0) on Windows8 and a possible bug I was facing. I have created a Service Request at Oracle Support and they are trying to reproduce with different constallations of Oracle Database software and Windows OS versions.
SR 3-7725167161 : Installing 2nd database with connection to 1st database moves connection to 2nd database
I was installing 12c(22.214.171.124.0) on Windows8 and from the DBCA I created my first instance called ORCLPR.
After the database was created I opened a command prompt, started sqlplus and connected to the newly created database ORCLPR. I then did a shutdown immediate and kept the sqlplus connection running – leaving the command window open. I then started DBCA Again and created my second instance ORCLDR. It completed successfully. I went back to my sqlplus command window and did a startup MOUNT which gave me the error “ORA-01100: database already mounted”. An alter database OPEN resulted in the error “ORA-01531: a database already open by the instance”.
When I executed select * from v$instance the sqlplus session had, to my big surprise, switched over to my newly created ORCLDR instance.
Below a screenshot of my sqlplus session showing the behaviour:
You can reproduce the issue yourself, by folowing the steps 1-7 below.
1: Install 12cR1 (126.96.36.199.0) on Windows7/8 – software installation only
2: Create 1st instance using DBCA
3: Connect to 1st instance using sqlplus and shutdown immediate – leave sqlplus session connected
4: Create 2nd instance using DBCA
5: When 2nd instance is up and running go to the sqlplus session still running
6: Perform “startup mount” – you will then see the error “ORA-01100 database already mounted”
7: Select * from v$instance will show that you now are on the 2nd newly created instance