Re: Index on foreign key constraint

> Why does Informix create a duplicate index on columns used in > foreign-key constraints? To make it easier to check for child rows when deleting rows from the parent table. Without these indexes, Informix would have to perform a sequential scan of the child table anytime there was a delete in the parent table to see if there were any matching rows in the child table. It would then either reject the parent row delete or cause cascading deletes in the child table, depending on the foreign key constraint definition. Mark Collins mcollins@us.dhl.com