Re: all foreign key should have index?

Frank, you have a point in that I did not answer the first question the OP asked IF FK require indexes, but I did answer the question if the results of his query were bad, 8-D.

For interested readers -
Where the referencing table is very small and will always be that way an index to support a FK is often not necessary. Also where the parent row is never deleted and the FK column is not updated in the parent then the index may not be necessary.

In general, the more concurrent DML on the parent and the larger the child table the more usful an index on the FK column becomes as Frank pointed out.

HTH -- Mark D Powell -- Received on Mon Jan 30 2006 - 15:59:44 CST