SQL Myth – Indexes and small tables

I have often heard people say that indexes or primary keys (and their associated clustered indexes) are not needed on small tables.  I just had a performance issue with a query and found the culprit to be a relatively small table that did not have any primary key or any indexes.  The problem was the small table was being hit with a full table scan inside a nested loop.  By adding an index it significantly changed the query plan and as a result performance increased by 87%.

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