"Dual criteria indexes" (was Re: What should fp 6.0 look like?)

[Howie]

----- Original Message ----- 
From: "Kenneth Brody" <kenbrody at bestweb.net>
To: "Howie" <howiewz at beonthenet.com>
Cc: "tom heine" <tch at aljex.com>; <filepro-list at lists.celestial.com>
Sent: Friday, October 22, 2004 5:22 PM
Subject: Re: "Dual criteria indexes" (was Re: What should fp 6.0 look like?)


| Howie wrote:
| [...]
| > | > associated fields working in dual criteria index's
| > |
| > | What is a "dual criteria index", and what "doesn't work" with them
with
| > | associated fields?
| > |
| >
| > It hasn't worked in quite a while.
| >
| > I assumed you and fptech were aware of it.
|
| Perhaps so, but not with the term "dual criteria index".
|
| > Example: You have a records with a set of state fields where {S1) PU
State"
| > are up to 10 states that the company picks up from and "S2) Delv State"
are
| > 10 states the company delivers to.
| >
| > If you build an index on s1) as the first criteria and s2) as the second
and
| > try to use it to find a company that picks up in say NJ and delivers to
CA
| > nothing will be returned, even though many records contain the requested
| > data.
| >
| > I understand that the example seems flawed and it should return any
record
| > that contains NJ in any of the S1) fields and CA in any of the S2)
fields
| > but that's exactly what we want - only nothing is returned.
|
| It's working exactly as designed, and it's doing exactly what you told
| it to do.  (Though not what you meant to tell it to do.)
|
| You have group S1 as the pick-up states, and S2 as the delivery states.
| Since they are both S groups, you have told filePro that they are
| matched pairs.
|
| For example:
|
|     @AF     1    2    3    4
|     S1      NY   NJ   DC   FL
|     S2      CA   WA   OR   TX
|
| This means that they pick up in New York and deliver to California, pick
up
| in New Jersey and deliver in Washington, pick up in DC and deliver in
Oregon,
| and pick up in Florida and deliver in Texas.
|
| If you build and index on S1 and S2, and look for a pickup of NJ and a
| delivery of CA, you won't find one here.  (ie: the NJ pickup gets
delivered
| to WA, and the delivery to CA was picked up in NY.)
|
| Based on your description (a list of pickups, and an unrelated list of
| deliveries), you need to use separate groups (such as S1 and T1).
|

Wow! I am so glad to be wrong about this one - It solves a number of
problems that we have been having.

I tested it and it works as Ken says, at least in DOS - I will test UNIX
later.

filePro and Ken are even smarter than I give them credit for.

Howie