Index a sum column

Question

Is creating an index for a column that is being summed is faster than no index?

Answer 1

If you want to make the summation faster, you can pre-materialized the result. On Oracle, use Materialized Views, on MS SQL use Indexed Views.

On your specific question "Is creating an index for a column that is being summed is faster than no index?", answer is No.

The answer to your question lies on Spencer's answer:

"An aggregate function (count, max, min, sum, avg) has to run through all the entries in a columns being summed regardless."

Just clarified the context of columns in Spencer's answer. His answer is correct nonetheless.