PUBLIC MARKS from ogrisel with tags sql & tree

Relational databases are universally conceived of as an advance over their predecessors network and hierarchical models. Superior in every querying respect, they turned out to be surprisingly incomplete when modeling transitive dependencies. Almost every couple of months a question about how to model a tree in the database pops up at the comp.database.theory newsgroup. In this article I'll investigate two out of four well known approaches to accomplishing this and show a connection between them. We'll discover a new method that could be considered as a "mix-in" between materialized path and nested sets.

First mail of a thread on the postgresql mailing list dealing of various ways to implement a tree structure with PostgreSQL.

This document describes an approach for handling hierarchical data in a relational database.