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The Value of Indexing Foreign Key Columns

Etienne Lopes takes us through a scenario:

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:

  • Always!
  • Never!
  • 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.