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Dick,
Everything you and Dennis say are predicated by trade-offs. Both approaches have strengths and weaknesses and it really comes down to both company and personal management.
I prefer the separate instances. To me it's much cleaner and easier to sort out. Security requests are applied to one instance (let Tom see this stuff). Downtime is the same across both approaches, although if you have separate instances, one client may be down for a specific reason (say a truly ugly batch process) while the other two clients are not affected. Same goes for a database restore. That was my suggestion. I like your hard-line response (pay me to fix it) but it leaves me with little other options (and we know that company politics sometimes makes these decisions).
I would have one shared Oracle home. Migration is applied one instance at a time. Simple but effective. Oracle patch sets are another animal. No choice but to evaluate and apply them to all instances where the risk is high.
So we disagree, but I think on personal principles.
tom
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Goulet, Dick
Sent: Thursday, July 07, 2005 9:44 AM
To: oracledba.williams_at_gmail.com; dubey.sandeep_at_gmail.com
Cc: oracle-l_at_freelists.org
Subject: RE: VPD vs multiple schems vs multiple instance
Dennis,
May I disagree?
Oracle patch sets are cumulative in nature. If one client wants a specific patch, which should NOT be their choice in a hosted environment they may well have to accept other patches that are not desired by their management. Face it if your hosting the application patching is for your benefit, not the client's. They just want the application to work and work in a secure and timely manner. Someone else stated that one client may want the database rolled back. WHY?? Their using the application, not managing it. If they messed up some of their data they can fix it themselves or pay your company to fix it for them. Rolling back the database is not an option.
My druthers, one instance, possibly rac'ed and mirrored, with one owning schema, portioned tables. Several users accessing the common tables with their userid being part of the data and primary key, and each user in a separate partition. If you really need to allow adhoc query access use a set of view definitions, similar to Oracle's user_<view> definitions. It's a lot easier and simpler to create the views and instead of triggers for each view than to build all of those VPD triggers.
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Dennis Williams
Sent: Wednesday, July 06, 2005 5:50 PM
To: dubey.sandeep_at_gmail.com
Cc: oracle-l_at_freelists.org
Subject: Re: VPD vs multiple schems vs multiple instance
Sandeep
I would advocate separate instances for the following reasons:
For example, one client insists an Oracle patch be applied
immediately. Another client insists that they can't possibly accept
the downtime required. With a single instance, you are forced to
choose between clients. With separate instances you can treat clients
independently.
There are advantages to a single instance from a shared pool
perspective. However, in my experience the frustrations outweigh that
gain.
Dennis Williams
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Received on Thu Jul 07 2005 - 09:01:45 CDT