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Re: relational tables and objects

From: Leandro Guimarăes Faria Corsetti Dutra <lgcdutra_at_terra.com.br>
Date: Tue, 29 Oct 2002 14:48:39 +0100
Message-ID: <apm3jn$2puii$1@ID-148886.news.dfncis.de>


Arkadiy Vertleyb wrote:

>
> The library implements an STL-compatible "relational table" container.

        Do you *really* mean _relational table_ or rather the more common _SQL table_?

        Do you mean a relation or a relvar?

> The full set of relational operators is implemented:
>
> -selection,
> -projection,
> -cross-product,
> -join,
> -union,
> -difference,
> -intersection,
> -groupby,
> etc.

[…]

> The operators can be combined in expressions using the technique known
> as "expression templates", so something like this can be written:
>
> print(projection >(selection(eq(1), employees))); //
> select an employee with ssn = 1, and print the name

        Do you provide support for mapping the data structures and the operations to relevant DSL, say SQL DDL & DML?

> We think that such a lightweight library could bring relational
> algebra into the areas where it previously was not considered because
> of the overhead and limitations traditional RDBMSs impose.

        There is no such a think as a "traditional RDBMS". Perhaps you are thinking "traditional SQL DBMS"?

> Consider
> writing a simulation system or a game. Which objects are located
> close to each other and so need to interact? All such pairs are
> easily found with join. What are integral characteristics of the
> system? Use groupby. And so on.

        I would rather have a lightweight, D-compliant relational engine built-in into the OS or development framework. Say Dataphor Alphora Lite… you might consider making your language D-compliant, see The Third Manifesto at http://www.thethirdmanifesto.com/.

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Received on Tue Oct 29 2002 - 07:48:39 CST

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