Re: [9fans] Multi-dimensional filesystem

[tlaronde@polynum.com]

On Thu, Aug 16, 2012 at 08:02:52PM +0300, Eugene Gorodinsky wrote:
> >
> > First one, related to what I was wandering about, is mathematical
> > definitions and relationships. Take the picture of the first volume of
> > van der Waerden's Albebra (I have the german edition and will keep the
> > german words). We speak about links between notions presented in a
> > linear order: the order of the chapters:
> >
> > Galois theory chapter is the descendant of concepts from
> > Vektorräume, Fortsetzung der Gruppentheorie and Körpertheorie chapters;
> > Vektorräume and Gruppentheory being siblings ("children" of Ringe und
> > Körper) while Körpertheorie is a grand-child of Vektorräume.
> >
> > Example of multiple parents, and not at the same level.
> >
> > This seems to be possible to recreate with befs, but I have to say: this
> particular problem is too specific to be solved with something like a
> filesystem. One should write a fileserver only when that would allow the
> user to use multiple familiar tools to work on the task. With your example
> it looks like the only thing the user would need here is the list of
> related topics along with the description of their relationship so that a
> related topic could be chosen and read. You can use a relational database
> for storage of the content along with the list of related topics and a
> program that can browse that database and follow the links. A user would
> never even think about doing something like 'cp ./Galors theory/parents
> ./Galors theory/children, even though the approach of implementing that in
> a fileserver allows that.

I think you missed the point. What I have given is an example, what
indeed made me wonder, initially, about a way to simply store
definitions as a text file, the relationships between the notions
being described by a directory structure. It was obvious rapidly
that this won't do in a classical hierarchical filesystem.

Say it is a "thought experiment". I don't plan to write a fileserver
just to implement this example. But multidimensional data is more widely
needed than this example. I have indeed cases where a fileserver like
that would allow storage of some data already stored in a database
(served by a database SQL engine, for example), and for which the
classical relational database is simply not a match.

Files have the benefits that you can use the text tools on them to grep
or whatever. And the file hierarchy reflects what is given by indexing
in a relational database.

Last, I always find it useful when I program or when I learn to ask me
questions about "what if" (as long as I don't spend the bulk of time
beating around the bush). One learns with exercices, questions, reading
a book a pen in the hand, simply because this is the only way to leave a
track in one's mind. Even dead ends are useful, since you know what is
possible and what is not. 

And I may do strictly nothing, at the moment, with some multidimensional
stuff, but use some of the solutions sketched, or something thought
about passing,  or part of a detail, to solve a non directly related 
problem later.

There is a paper by D.E. Knuth, IIRC, speaking about the usefulness of
"toy programming". This is it.

-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                      http://www.kergis.com/
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