Re: The same simple question to relational theorist (with video now).

пятница, 5 апреля 2013 г., 2:43:22 UTC+4 пользователь Cimode написал:
> Le jeudi 4 avril 2013 20:22:04 UTC+2, Jan Hidders a écrit :
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> > On 2013-04-01 16:29:26 +0000, Evgeniy Grigoriev said:
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> > > Hi everyone.
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> > > Last year I asked a question:
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> > > "…is a way of how I create the normal relations important? Suppose a
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> > > part of system exists which creates the relations according to some
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> > > external non-normar expression descrided some data. This part of system
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> > > translates external expression into commands which create a set of
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> > > normal relations. So user of such system gives to the system some
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> > > non-normal data description expressions but operates with the data
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> > > presented in form of normal virtual relations only. (once again - all
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> > > data are presented for user in form of normal relations). Is such
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> > > system relational?"
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> > The answer depends a little on how you define "the relational model"
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> > and that is not uncontroversial, but I would say that if the generated
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> > tables satisfy all the required properties of relations and you
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> > manipulate them in the relational way, they are relational.
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> > > Now I can demonstrate a prototype which implements a very simple idea:
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> > > as soon as data have been described in object-oriented way, they are
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> > > immediately represented in relational way. You can see a video by link
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> > > (720HD is available) ---> http://youtu.be/K9opP7-vh18 .
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> > So how does your ORM differ from the other ones, like for example Hibernate?
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> > -- Jan Hidders
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> A new ORM. Check this one out.
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> http://www.maddash.net/videos/intersystems/cache/demo/

I'm not sure if you reply was addressed to me. But anyway I look through video presentation and I've found some detail which I don’t like me in the Cache's video. It's my reaction on this video.

• Object has two different stages – object instance have to be load from table and then write back in table. I don't want the two stages. I don’t want to think about where the object is, in memory or in table. I don’t want to "reload" object into memory after changes were made in the table. I want to work with persistent object.
• A class is mapped into a table. One class = one table (I think that you know how this idea is bad). I don’t want to think about what table is corresponding to class. I don’t want to work with single object in memory but with group of objects (sorry with their data) in the table. I want to work with active persistent objects. It may be a single object or group of object or whole class - no matter.
• I don't want to think about tables but I want to see the data presented in relational form. I don’t want to think about how classes are mapped into _evident_ tables because it means that I have to think how the tables have to be joined. Let system join, bind, calculate and process. It can.

All the "want" and "can" are implemented in RxO prototype. You can see my video.

PS. XML example looks like they don’t think about possible complex structures at all. Suppose I want to describe genealogy tree, so I create class PERSON, and each PERSON object has two references on pa person and ma person (by the way, is it possible in demonstrated system?). I will afraid to run XML query because all the person ancestors will be in result. Has the "XMLExport" function ability to form or to restrict a result? Received on Wed Apr 10 2013 - 22:55:45 CEST