For better performance, you would typically put the more unique value
first in the index, then the less unique. With this index you would
look up everything on the shelf, and coincidentally (for lack of a
better term) filter by the warehouse.

That is unless you are striving for an index only retrieval path - then
you would put your keys in most to least unique order, followed by the
desired result column. So, if you are looking for the item number on
the shelf in the warehouse, you would have IO only against the index if
the index was shelf, warehouse, item number. This is typically used in
complex searches against large tables with many columns.

I haven't checked yet - does firebird support index only access paths?

On Fri, 2004-11-19 at 10:34, Ann W. Harrison wrote:
>
>
> >
> >At 11:08 AM 19/11/2004 -0500, Ann wrote:
> >
> > >If the fields are listed as warehouse, shelf, you can use that
> > >index to lookup everything in a warehouse
> > >or everything on a particular shelf in a warehouse.
>
> At 11:08 AM 11/19/2004, Helen Borrie wrote:
>
> >Only if you include warehouse in the search, since the shelf segment won't
> >be visible for a shelf-only search, right?
>
> I should have said "everything on a particular shelf
> (or range of shelves) in a particular warehouse.
>
> Cheers,
>
>
> Ann
>
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>
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