Re: Using Multiple Databases

Byron Pearce (bpearc1_at_tisdec.tis.tandy.com) wrote:

<about having two database instances on the same machine> We do this all the time - we have one (Sequent/Unix) machine with 5 instances on the same box. We've even run multiple REVISIONS of Oracle (ie, 6.0.36 and 6.0.34 or 6.0.36 and 7.0.12) on the same machine, but that's another post.

: 1. How much overhead are we talking about in having two databases?
Well, for starters you've got the disk space for the data files (you should be able to share ORACLE_HOME as long as both DBs are at the same rev level). Then, you'll have whatever process load the second database will put on your system.

: 2. What type of performance cut (ballpark estimates are fine)
: will the system take from two databases?
Depends on the process load - the only other hit might be if your data files had to share the same disk I/O channels.

: 3. What are the effects on the existing programs that are already
: connecting to the existing database using '/' and not
: specifying an "AT" in the "CONNECT"?
Well, the way we set things up is with a little script that sets some environment variables (LOGICALS to VMS folks) that point to a different ORACLE_SID, but the same ORACLE_HOME. You've also got to make sure that you have database accounts in the right places.

: 4. What will be the effects on the Oracle Tools (SQL*Forms, etc.)?
Shouldn't be any - of course, you'll have to keep both databases at the same rev level unless your want to set up a different ORACLE_HOME.

: 5. Would a single program, form, etc. be able to access both
: databases at the same time?

Yeah - but it's a bit ugly. I dunno about FORMS4, but from FORMS3 you'd have to do either a user exit or a database link. From PRO*C (or PRO* <insert your favorite language here>), you can actually set up multiple connections (I haven't actually tried this, but the documentation says it can be done).

: 6. What other effects (positive or negative) might this have?
Not sure - we haven't had a lot of trouble - other than pointing at database A when we wanted database B (but not often, since we keep the passwords different for just that reason).

Good luck!

--
Clay Jackson - N7QNM
US WEST NewVector Group Inc
Bellevue, WA
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