Database Administrators Stack Exchange is a question and answer site for database professionals who wish to improve their database skills and learn from others in the community. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

What do indexes look like in an Entity Relationship Diagram?

I've googled it and I'm unsure what the standard look of an index is in an ERD. And I'm talking about the crowsfoot diagram that includes all of the fields.

share|improve this question
Why do you want to show indexes on ERD? Most tools provide a physical view of the model where you can denote and name indexes, but not on the ERD diagram itself. – NoChance Sep 4 '12 at 6:37
up vote 7 down vote accepted

They don't tend to be shown in ERDs. An ERD focuses on the Entities and their Relationships, but an index is a copy of the data from one (or potentially more) of the entities, created to assist in the execution of queries. While it's possible that an index could be unique and therefore contribute to the database design, they are not typically shown on ERDs.

...which is a shame, because in my experience, a database design should involve careful acknowledgement of the indexes, as they can make-or-break the effectiveness of a database system.

share|improve this answer
this is not a shame but it is not the intention of the entity relationship diagram to document physical implementation but to provide a conceptual model. The entity relationship diagram (usually with additional information) can be used to develop a physical implementation. – miracle173 Sep 4 '12 at 6:34
Sure. But there is no diagrammatic standard for indexes (so much as I'm aware) - and that's a shame. – Rob Farley Sep 4 '12 at 7:05
While there is no standard the CA Associates ERwin tool does enable indexes to be shown using the words "IEx.y" or "AKx.y" where x is the index number and y is this columns position in that index. That convention is helpful to query writers when using the ERD to help them navigate the database for joins. I hope this helps. – Todd Everett Sep 4 '12 at 21:44

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.