The PostgreSQL Conference 2011 :"Trees and Graphs in the database" https://www.pgcon.org/2011/schedule/events/357.en.html

* Trees in the database - Slides: http://www.slideshare.net/quipo/trees-in-the-database-advanc...

* Graphs in the database - Slides : http://www.slideshare.net/quipo/rdbms-in-the-social-networks...