Re: Trees in SQL

Try here maybe:

http://cddb.sai.msu.su/~megera/postgres/gist/

Look at their new 'tree' module...

Chris

----- Original Message ----- 
From: "Gregory Brauer" <greg@wildbrain.com>
To: <pgsql-sql@postgresql.org>
Sent: Friday, May 24, 2002 11:08 AM
Subject: [SQL] Trees in SQL


> 
> I hope this isn't an overly broad topic that ends up diverging into graph
> theory, but I have a tree structure of identical items (analogous to a
> filesystem directory tree) that I need to store in Postgres.  The
> "obvious" design is to give the table that will represent these objects
> a field identifying its "parent" that is a relation to the same table.
> However, this seems to make many common SQL queries rather difficult.
> 
> What sort of strategies are best for storing tree structures in a
> relational database, and how would one structure SQL queries to find,
> say, "all of the children anywhere under this node", or to represent
> the condition "if this node is a child at any depth under this other
> node"?  Are there good strategies for preventing cycles?
> 
> I'd appreciate any insights anyone can give.
> 
> Thanks.
> 
> Greg Brauer
> greg@wildbrain.com
> 
> 
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