de-installation surprises

There are lots of stories on the web about how to do an oracle installation. For de-installations there a not so many notes around. Until oracle 10g life was fairly simple, you could just run de oui from $ORACLE_HOME/oui/bin/runInstaller, select the ORACLE_HOME to de-install, wait for the process to complete and remove the ORACLE_HOME directory from the filesystem.

10gR2

Then came oracle 10gR2, with a little surprise, it not only de-installed the requesten ORACLE_HOME as an extra 'service' for customers, it also removed the SQL*net files, sqlnet.ora, tnsnames.ora and listener.ora. If you happen to use the files from the ORACLE_HOME/network/admin/ location, you would have thrown them away any way so that would not be a big deal. However, if you have them in a location specified by TNS_ADMIN, or in one of the other default locations like /etc/ or /var/opt/oracle/, they are removed from there also. Sometimes this might be ok but in a case where you have multiple ORACLE_HOMES for multiple Oracle databases this certainly is not what you would have wanted.

In order to prevent the unwanted removal of the SQL*net files, we can force the installer to only visit the location pointed to by TNS_ADMIN. What I do in this case is:

export TNS_ADMIN=$ORACLE_HOME/network/admin
$ORACLE_HOME/oui/bin/runInstaller

and remove the ORACLE_HOME. Now the installer only removes the SQL*net files from the ORACLE_HOME/network/admin that you were to remove any way so that is no big deal.

11gR2

Release 11g has even more surprises in it's sleeve, it also removes the oratab file. For this I did not - yet - find a solution. I don't like this. This removal comes from one of the root scripts that we need to run to complete the task, in the case of removing the clusterware installation, so we could adjust those scripts not to do this but I really wonder why Oracle thinks to help the customers this way. This is not the help that I think customers need. It would be OK if we were given a choice, remote the administration files, or not. Removing the bluntly as they do now .... No, please don't.