>In your example, if I need all "D" reservations from last week, I'd probably only create an index on the date, but if I need all "D" reservation in the entire table, I'd add an index on the reservation type. If I have to count the number of different reservation types last week, I'd add an index on both fields.
>
>Christof


That jives with my thinking, Christof. It's very unlikely that one would ask for all the "D" reservations which would include all of the 1999, 2000, and 2001 reservations.

Almost always the request would be for reservations for this week, next week, today, a span of unit numbers, etc. The request would then be qualified by specifying some combinations of reservation types. Definitely need an index on week, start date, unit number, etc. but I think I will do better without the index on type.

Given that there are usually other (indexed) factors, what do you think about the "no index when less than 10 discrete values" rule-of-thumb?

Peter