delete for date = vDate
This would use any index on field "date", if it exists.
Change this to:
delete for date+1 = vDate + 1
This would not use an index on field date. It would, however, use any index on "date+1", in case you have one! Which you surely don't.
Hilmar.Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)