Trees in the database: Advanced data structures

Lorenzo Alberton wrote in his blog about his paper presented at PHP conference

Storing tree structures in a bi-dimensional table has always been problematic. The simplest tree models are usually quite inefficient, while more complex ones aren’t necessarily better. In this talk I briefly go through the most used models (adjacency list, materialized path, nested sets) and introduce some more advanced ones belonging to the nested intervals family

ED: some of the principles can be applied to Firebird with CTE