Let me start this post with a question, “Do you think that it can be beneficial to have a single column index for the foreign key column in the child table?“
Well, I believe I can ear three types of answers to this question:
- It Depends…
Click through for Etienne’s answer. I’d still prefer these indexes to have multiple uses, which generally means having enough columns on the index to act as a covering index for one or more important queries. But Etienne does show a good use case for this single-column index.