This article is an extension of my previous article This time, however, I will write the algorithm completely in PostgreSQL’s PL/pgSQL. For background information and to understand the premise of this post, please glance through my previous post.
Ok now that you’re familiar with what we’re working towards, here’s my assumption of your database structure:

You have [...]

As the final question in one of my interviews a while ago, I was asked to compute the average degrees of separation in social networking site. If you don’t know what degree of separation, here’s an example.
Amy is a friend of Robert. Therefore, Amy and Robert are 1st degree friend. Robert is a friend of [...]