Hello Every time a PK is declared on a table, a corresponding Index is created automatically. But every time a foreign key is declared, the corresponding Index has to be created manually. Since it is recomended that an index must exist for every FK on a table (unless I am wrong), why the index is not created automatically? I have other question: Strictly speaking, if one wants queries to run fast, are Keys of any use? I mean, is it only required to create appropiate indexes on a table when optimum performance of queries are the objective? Thanks a lot.