Re: Generic Modeling

In article <60360d48.0201031424.7e125f2_at_posting.google.com>, Brian Smith says...
>
>D_at_B.A wrote in message news:<z82Z7.2503$cD4.4766_at_www.newsranger.com>...
>> In article <60360d48.0201022255.b17627a_at_posting.google.com>, Brian Smith says...
>
>> >Futher, I don't doubt that a RDBMS could be built on top of an OODBMS;
>> >similarly, I think that you could be an OODB system that stored
>> >information in an underlying RDBMS.
>>
>> Building one thing on the top of the other can't hardly be anybody's
>> motivation.
>
>I was trying to hint that an RDBMS isn't necessarily more powerful
>than an OODBMS and vice versa, by saying (but not proving, obviously)
>either one could be implemented by the other.
>
>> I would like to see how would you query the equipment scattered at various
>> levels of the hierarchy in OODB.
>
>So would I.
>
>> >I know you can do this really easy by using a "THING" table in SQL,
>> >because I have already created something like that using two tables.
>> >For the deep copy it helps to have a recursive query operator like the
>> >Oracle "CONNECT BY". Then you just do an INSERT INTO ... SELECT ...
>> >CONNECT BY ...
>>
>> One more time, the more obscure concept of the language you use the more
>> chances are that optimizer doesn't supports it yet. Hierarchical subqueries
>> are not unnested by optimizer, for example.
>
>Well, in very limited testing, Oracle9i was able to do a pretty good
>job with my hierarchial query, and it included an outer join and three
>inner-joins between two tables, along with a DISTINCT clause to filter
>out duplicates (I didn't have a hierarchy, I had a directed graph, so
>I needed DISTINCT to filter out the items that were part of multiple
>"hierarchies" in the graph). But, I will have to see how my prototype
>system scales when presented with a larger amount of data.
>
>Thanks,
>Brian
Received on Fri Jan 04 2002 - 00:06:53 CET