What is a basic algorithm for related content queries?

Question

Let's say I have a DB of questions, like SO! When a user has asks a question, I'd like to provide related questions on the sidebar.

Is there a standardized technique for this? Split question by spaces, search on each word, etc... ??

Not really sure where to begin.

Answer 1

This is known as More Like This feature. IR libraries like Lucene support this feature. Read here for more details.

1. How MoreLikeThis Works in Lucene
2. Using Lucene and MoreLikeThis to show Related Content