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Home -> Community -> Usenet -> comp.databases.theory -> Re: The Fact of relational algebra (was Re: Clean Object Class Design -- What is it?)

Re: The Fact of relational algebra (was Re: Clean Object Class Design -- What is it?)

From: <D_at_B.A>
Date: Sun, 09 Sep 2001 23:12:55 GMT
Message-ID: <XHSm7.1515$%u4.1538@www.newsranger.com>


In article <9ngc8f$de9$05$1_at_news.t-online.com>, Adrian Veith says...

>Again you can't see the difference between left and right. A collection is a
>subset (sub not super) of a relation. But in real live databases, you are
>confronted with 80% of relations, that can be described by a collection.
>Therefore does a collection saves you from the task of doing stupid things
>again and again.

When insering into a collection does OODBMS locks the whole collection? Or programmer explicitly specifies the lock? Those questions are hard even in relational model; this is how predicate locks, for example, were invented. Predicate locks happened to be fundamentally unefficient, but at least the concept was identified. When object people don't even have a common object definition, how can they hope to be able to handle hard subjects like concurrency, for example?

Of course, this issue doesn't matter for CAD systems, but I wonder are there crazy people who implemented a banking system with OODBMS? Received on Sun Sep 09 2001 - 18:12:55 CDT

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