Hubert,
> i recently spent some time on tree-structures in sql. > i started with simple id/parent_id approach, used by nearly everyone, > then i stopped at joe celko's nested sets, but i found it not very > usable. I'll be posting an article on implementing nested set trees "real soon now". My experieince: Adjacency list trees are easier to understand conceptually, there are more tools on freshmeat.net for them, and they are the most efficient form of tree for graphical display. Nested Set trees are hard to wrap your mind around, lack a lot in the way of code samples on freshmeat, are harder to build GUI tools for, but are much, much faster for determining branch membership and branch parenthood. So which model you use depends on what you intend to do with the tree. -- -Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
