[Dbix-class] Representing directory structures

Ben Tilly btilly at gmail.com
Mon Apr 8 01:43:04 GMT 2013


http://www.ibase.ru/devinfo/DBMSTrees/sqltrees.html is a good read for
anyone who wants to construct hierarchical data structures.  It would
need some modification to handle "shared folders."

On Sun, Apr 7, 2013 at 11:42 AM, Bill Moseley <moseley at hank.org> wrote:
> Anyone using DBIC to represent hierarchal directory (folder) structures?
>
> Essentially just like a file system, except users each have their own root.
> To add to the complexity, I need to be able to "share" folders and all child
> elements to other users.
>
> My assumption is this would involve a single table where each row can
> represent either a directory entry (e.g. a "file") or a sub-directory that
> references its parent.
>
> Postgresql has "WITH RECURSIVE" which DBIC has no support for (other than
> virtual views):
>
> http://www.postgresql.org/docs/9.2/static/queries-with.html
>
>
> But, Adjacency Lists and Nested Sets are (were?) often discussed as
> solutions for hierarchal data in the database.  I asked on the Pg list back
> in 2007:
>
> http://postgresql.1045698.n5.nabble.com/Adjacency-List-or-Nested-Sets-to-model-file-system-hierarchy-td1876116.html
>
>
> but, so far, I've happily avoided using these approaches of representing
> hierarchal data in the database.
>
>
> BTW -- I have recently written a "tag"-based system (like the familiar
> gmail) which is easy to represent in a highly normalized schema but is a
> fundamentally different approach.
>
>
> --
> Bill Moseley
> moseley at hank.org
>
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