Types of Conditions
•Date-range
restrictions specifically related to a date pertaining to the
events.
–E.g., “Orders shipped in the past week,” “This month’s
customer complaints”
–These begin as unselective, before history accumulates,
but become highly selective as history piles up – design for the old
system, not for the new!
–These
date columns are useful to index, but they should usually be the last
column of the index, because they are reached with range
conditions, not with equalities.