Re: Patching Oracle without shutting down the database

Vsevolod Afanassiev wrote:
> Somehow it appears to be possible to patch Oracle on AIX 5.3 without
> shutting down the
> databases - and everything works fine!
> - We have several AIX 5.3 servers running Oracle 9.2.0.7.0 Enterprise
> Edition
> - Partitioning Option wasn't installed
> - I installed partitioning option by running 9.2.0.1.0 Installer, then
> 10g Installer then comes with 9.2.0.7.0 Patch Set, and then Patch
> 5496862 using OPatch - and then realised that the database was up.
> - Everything seems OK, there were no errors during installation,
> timestamp on the file $ORACLE_HOME/bin/oracle shows that it was
> re-created, I can shut down and start the database, partitioning works
> - The experiment was repeated on the second server with 6 databases
> running - same result.
>
> Is it a feature of AIX?

In general, when you run an oracle executable under unix, it starts up and then stays in memory. If the executable goes away on disk, the original continues to run in memory. If open files go away, oracle still accesses them because it is using program file handles from when the program started rather than descriptors from the filesystem - so they still don't go away for real until oracle closes them.

The problems occur when something gets read in from disk, and doesn't agree with what is in memory. Unless you take the time to figure out everything that is running and called into memory for all your applications, you can't predict what will happen.

Remember, when you patch, there are several different things that can happen - you can replace scripts, you can replace or rebuild executables, you can update tables, you can update procedures, you can change file protections, etc. It is impossible to properly test all of these things with a different procedure than the documented one (in fact, stuff gets missed in the much larger regression testing that Oracle does). So your "everything works fine!" statement is suspect. You may indeed be lucky. Do you feel lucky? If you were on some other platform, you probably would have had some part of the install or patching mess up with file locking issues.

See catpart.sql, anyways. Part of your luck is probably due to not having already used partitioning.

jg

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