Conference orarep::nomahs::dbstars

742.0. "hierarchical dbi db's vs single level" by BROKE::BITHER () Thu Jan 30 1997 13:12

From:	BROKE::ABUGOV       "Database Integration and Interoperability" 30-JAN-1997 12:45:05.85
To:	DIANE
CC:	RENEE STEVE ME
Subj:	hierarchical DBI databases


Hi Diane,

I sould suggest to the customer to put all Rdb databases in a single DBI 
catalog.  Not only is there a maintenance overhead associated with keeping 
other catalogs around but also there is a performance hit from going dbi to dbi 
to rdb instead of just dbi to rdb.

There are two places where i would think of using hierarchical DBI databases.
One is as a protection scheme (let some users have access to a lower level DBI, 
and all users have access at some higher level with a subset of what is in the 
lower level DBI database).  The other would be when there are gateways 
involved, and by moving a DBI database closer to the data there is potential to 
be able to integrate data at locations closer to the data and not have to 
stream lots of info to one dbi to do all of the work.  It has to be carefully 
thought out though, and in this case where all the databases are Rdb (fully 
capable dbms) and the use of an integration wouldn't buy them anything I 
wouldn't suggest they use DBI to DBI.

Hope this is semi-clear....

Dan

*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=

From:	BROKE::BITHER       "Please reply to [email protected]" 30-JAN-1997 09:45:13.66
To:	ABUGOV, BASTINE
CC:	BITHER
Subj:	? on hierarchical dbi catalog dbs (Henry Ajayi)

Hi Dan,

I have a new dbi customer who has 5 Rdb databases on the same
node.  One db is on a different disk drive, the other 4 are on the
same disk drive.  Customer read somewhere that hierarchical dbi
catalogs were a good thing for performance and their plan is to:

Database1  Put these in DBI catalog A
Database2

Database3  Put these in DBI catalog B
Database4

Database5  Put this in DBI catalog C

Create DBI catalog D that points to dbi catalogs A,B,C.  That way he
would have 2 levels of dbi catalogs and have formed a hierarchy.

I told him I thought this was more of a location thing.  Like if db1
and db2 were in New Jersey and the others were in New York, maybe
use a separate dbi catalog for the ones in N.J. and tie in to the
parent dbi catalog in N.Y.  But that's all I said and don't even know
if it's right.  Can you expand on the pros and cons of hierarchical
dbi databases?  This is the first customer that ever asked about this.

Thanks, Diane