EXPLAIN EXTENDED

On Jul 1, 2009, PostgreSQL 8.4 was released.

In this series of articles, I'd like to show how to reimplement some tasks I wrote about in the previous blog posts using new PostgreSQL features.

Previously in the series:

• Flattening timespans: PostgreSQL 8.4

Now, let's see how we can implement the hierarchical queries using the new features of PostgreSQL 8.4.

In PostgreSQL 8.3, we had to create a recursive function to do that. If you are still bound to 8.3 or an earlier version, you can read this article to see how to do it:

• Hierarchical queries in PostgreSQL

In 8.4, we have recursive CTE's (common table expressions).

Let's create a sample hierarchical table and see how can we query it:
Read the rest of this entry »