A databse is not strictly a heirarchal tree. This is a rather common mis-application of a tree-type datastructure.

A tree is a conceptually simple datastructure. There's a root node with one or more children, and each child has one or more children, and so on. Strictly speaking, trees are acylic (this is where problems arise--read on). It's a good datastructure for a lot of problems, but it is not the only one, nor is it the best solution to all problems.

Relational Theory is based on set theory. You can implement a set as a tree, and relational databases will support it (though you have to do some hoop-jumping to get SQL to handle it). However, there are many other structures you could also build into a relational database (ones which SQL is also much better equipted to handle, though this is SQL's failure, not Relational Theory).

IMHO, people over-apply trees, and then try to introduce hacks when the structure doesn't fully map to the solution. For instance, symbolic links in a filesystem could be considered an attempt to coerce a tree structure into a general set structure. Symbolic links mean that your file tree is no longer acylic.

What I really want to see is the opposite direction the OP was thinking of: make the filesystem a relational database. Kill off the tree structure entirely, and lump all the files together. You get specific files by running some query language against them. There are projects doing something more or less like this (Microsoft's WinFS and ReiserFS 4, to name two), but nothing usable on a production system yet.

"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.

In reply to Re^2: RFC: Fuse::DBI - mount database as filesystem by hardburn
in thread RFC: Fuse::DBI - mount database as filesystem by dpavlin

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