Is it possible to avoid "Using temporary" when distinct is used with join?

[Wai Yip Lau]

Let say I have this query:

SELECT DISTINCT(consumer_id) FROM consumers INNER JOIN consumer_opts ON consumer_id=consumer_ref;

And I have the id as the primary key. I always get the "using temporary" notice.

I can't use a right join because I need to look at some extra columns in the consumer_opts table.