>why can't "select A,B from foo" be served directly from the index mysql supports that with covering indexes. https://books.google.co.uk/books?id=IagfgRiKWd4C

>why can't "select A,B from foo" be served directly from the index mysql supports that with covering indexes. https://books.google.co.uk/books?id=IagfgRiKWd4C&lpg=PA178&vq=covering&pg=PA177 https://books.google.co.uk/books?id=IagfgRiKWd4C&lpg=PA178&v...