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Home -> Community -> Usenet -> c.d.o.misc -> Re: Object-Relational Databases
> I want to familiarize with object reletational databases, and I have
> some questions for introduction.
First of all, there is no unique standard in OODB's or ORDB's, so the terms can mean different things to different people, but once said so, here come my opinions.
> What is the difference with object relational databases and object
> orientented databases?
In theory, not much (depending on who defines each). The main difference would be that OR DB's have to keep 'compatibility' with relational databases; but most OODB's try to do this one way or another.
In practice there is one big difference: OODBs usually implement the ODMG2.0 standard, while ORDB's try to implement SQL3 (which is not yet a standard, but hopefully will be soon).
The way I see it is that they will become almost equivalent sometime (probably in the next 5 or 10 years), since the ideas are very similar and most of the differences is marketing hype and where are they coming from.
The 'pure' OODBs come mainly from OO languages. They were initially more like persistence engines, but they are becoming true databases now.
The ORDB's come mainly from relational, so they are good databases, but have been lacking in OO features.
And have the idea that a lot of the difference is just marketing. If I'm a 'new' OODB vendor, I'll tell you they are much better than relational, so you trow away your ol RDB and buy my product. If I'm an 'old' DB vendor, I'll say OODB's (now ORDB's :) are just an improvement over the old ones, so don't buy another guy's DB, buy my new version. (just an idea :)
> What is the difference between relational databases and object
> relational databases?
ORDB's are essentially an improvement over traditional RDB's, but they allow you to define your own datatypes; they 'borrow' the concepts of OO (mainly classes, OID, inheritance and polymorphism) for how you define your types, so they are Object-Relational.
> Is special Oracle 8 a relational database with some nice extensions
> (e.g. nested Tables, Blobs),
> or is it already object-relational.
I don't know much about Oracle 8, but for what I've read they are pretty much OR, and those nice extensions (and some others) are what make a DB OR and not simply R :) (BTW I think Oracle 8 has several different version, of which only the 'highest' (Enterprise ?) is actually OR).
Some books:
OR-> Object Relational DB's: The next great wave. Stonebraker (probably misspelling :); there are some books about SQL3, SQL99 and the like.
OO-> There are a lot. some good (IMHO) books are by (Richard?) Cattell, Elisa Bertino, ?? Rao ... (their titles have OODBs on them :) Also the ODMG2.0 standard (which is by Cattell also)
Hope this helps.
Orlando
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Received on Thu Aug 05 1999 - 13:37:02 CDT
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