Re: Creation of Oracle databases

You can create a single database within Oracle, for sure, comprised of multiple tablespaces and using several schemas to keep data separated (user security etc). Whether that's a good idea or not depends... do all 5 of your databases behave in the same way? Do all 5 need complete data recovery? Are all 5 required to be up 24 hours a day? Can all 5 be shutdown simultaneously? Are all 5 OLTP applications, or all DSS applications?

If the answer to any of those questions is 'no', then sticking them all into the one database is not a good idea. An Oracle database either produces archives or it does not. You can't have a bit of a database producing them, and another bit not. That could mean that you were generating unnecessary archives.

Tuning is at the database level. If you have a mix of OLTP and DSS applications, then tuning will inevitably sub-optimal for both, as you struggle to make the necessary compromises. If the transaction rate on one application is high, expect the performance on the other 4 to be affected.

If you need to take the database down for maintenance, all 5 applications will be out of action for the duration. Is that acceptable?

On the whole, I tend not to like having separate applications within the one database, and Oracle would generally advise you likewise (but then Oracle tends to assume you have vast hardware resources and an infinitely stretchable budget). But that's not to say it couldn't work, or that it wouldn't be the most appropriate solution.

Unfortunately, "it all depends"!

Regards
HJR "Meng" <m.fangtao_at_genesis.co.nz> wrote in message news:1ddc56b5.0106241842.2a112f31_at_posting.google.com...
> Hi,
> We will migrate Mysql to Oracle soon. Now I have a question. We have
> 5 databases in one instance in Mysql. Do we need to create 5 databases
> in Oracle, or only one? We have to start 5 instances and assign
> different sizes of RAM to them If we create 5 databases. Thanks in
> advance.
>
> Meng
Received on Sat Jul 21 2001 - 16:15:59 CDT