Adjacency List or Nested Sets to model file system hierarchy?

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От Bill Moseley
Тема Adjacency List or Nested Sets to model file system hierarchy?
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Msg-id 20070212002010.GB30253@hank.org
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Ответы Re: Adjacency List or Nested Sets to model file system hierarchy?  ("Merlin Moncure" <mmoncure@gmail.com>)
Re: Adjacency List or Nested Sets to model file system hierarchy?  ("Ian Harding" <harding.ian@gmail.com>)
Re: Adjacency List or Nested Sets to model file system hierarchy?  ("hubert depesz lubaczewski" <depesz@gmail.com>)
Список pgsql-general
I'm looking for a little guidance in representing a file system --
well just the file and directory structure of a file system.

Often articles on representing a hierarchy discuss the advantages of
using Nested Sets (or nested intervals) it seems.  I'm not clear how
well they apply to a file system-like hierarchy, though.

The examples (and my limited understanding) of Nested Sets have the
leaf nodes at the end of the branches, where in a file system a node
can have both leaf nodes (files) and branches (directories).

Also, the Nested Sets seem to solve problems I don't have -- such as
finding all descendants of a given node.

My simple requirements are:

    -- Quickly be able to lookup content by a full "path" name

    -- Provide "directory" views that shows parent, list of contents
       including any "sub-directories".

    -- To be able to easily move branches.

It will not be a large collection of "files" in the tree, so that's
not an issue.

Seems like an Adjacency List along with a de-normalized "path" column
in the leaf nodes would meet the requirements.  But, as I see nested
sets discussed so often I wonder which is a better approach.

I assume this is a reasonably common problem so I'm curious how others
have implemented it.

Thanks,


--
Bill Moseley
moseley@hank.org


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