Paul White NZ (4/20/2010)
Including the trivial case where the table has one row, if the rows in the table fit on a single page, SQL Server has a perfectly 'efficient' way to retrieve the rows. That is why I said it depends on the number of rows.
Yes, you are right. For a single page, or even just a few dozen pages, scanning the table is fast enough to be called "efficient". I did not consider that when phrasing the question.