Re: RDBMS Server Features Matrix - Beta Draft

>Dan, can u kindly explain the following features mentioned in your
>matrix :
>
>1. What's CASCADING UPDATES ? What sort of circumstances/applications would
> this be necessary ? Can u give an example ?
Think first of delete cascade. When you delete a row in a parent table all of its children are also deleted. Example: Delete a row in the orders table and all the corresponding line items get deleted. Now imagine the same thing for an update. You update the primary key in the parent table for some stupid reason - as soon as you do this you have invalidated all the rows in your child table as their foreign key is no longer valid. So therefore Cascade update would keep these records in synch. And yes, it is probably stupid and violates relational calculus in somewhat to change your primary key value, but some people seem to want to do it... And I don't think triggers will work to do this since you violate your declarative integrity rules as soon as you update your parent record...
>
>2. Multi-Protocal Routing
> From what I understand, the RDBMS vendors provides a connectivity software
> that sits on top of either DECnet, TCP/IP, named pipes, etc to
> communicate with the remote RDBMS server. My organisation uses TCP/IP
> to communicate with the host, however we have a lots of other network
> drivers sitting on the client's desktop too. Therefore would this
> feature be of significance to our environment ?
> If not, under what sort of setup would this be crucial.
>

Most of the vendors that allow distributed queries let you go via one protocol to your initial server, and distributed queries that spread out from there to other servers may go across other protocols. Typical example is PC Client talking to Lan RDBMS Server over SPX/IPX, and then part or all of a distributed query going from the LAN RDBMS Server to the mainframe over TCP/IP or LU6.2...

Oracle also has (late beta or early production, I think) a gizmo called the Net Interchange. This is basically a high performance software router that eliminates the need for the Lan RDBMS Server in the scenario above. It is a good solution for a company that has a huge Novell Lan or Appletalk LAN, and wants their PC's to be able to access TCP/IP, DECNET, or LU6.2 machines without having to purchase TCP/DECNET/LU6.2 for every PC. I believe this product is initially only for Oracle SQL queries but they want to extend it to include file transfer/RPC/Print Services/Etc... I also remember it is fairly intelligent in terms of best path routing, alternate paths in case of failure, etc...

I think Micro-Decisionware may also have a similar product.

Hope this helps,

• Dan

Daniel Druker
Anderson Graduate School of Management at UCLA                    

| Dan Druker                                                               |
| agsm mail 	: ddruker                                                  |
| internet 	: ddruker_at_agsm.ucla.edu                                    |
| oracle*mail	: unix:ddruker_at_agsm.ucla.edu                               |
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Disclaimer: None. I'm a student now and I don't care what you think. Received on Sat Jun 05 1993 - 12:00:03 CEST