Re: Order of key fields

[Gary Thompson <GThompson@xxxxxxxxxxx>]

George wrote:
> What I'm wondering is if there is a signifigant performance advantage
> (or penalty) to ordering them according to their variability. In other
> words, given a situation where you have a lot#, case#, piece# with many
> pieces# per case, per lot, would a key order of (lot, case, piece)
> affect performance differently than (piece, case, lot)?


My understanding is the most frequently uses fields should appear before 
any others in the key list.

The idea is that row selection, think SQL WHERE clause, is a main factor 
in access path selection;
therefore those fields more frequently used as WHERE criteria should 
appear before others.

I do think there is a general recommendation for fewer access paths that 
are "wider" as
opposed to many "narrow" access paths.