Re: Logical Files vs. Physical Keys

Not necessarily so. For instance if you are using a hashing function to
generate the key then you have to rely on collision detection :-)

Eric

______________________________________________
Eric N. Wilson
President
Doulos Software & Computer Services
2913 N Alder St.
Tacoma WA 98407


----- Original Message -----
From: "Mike Cunningham" <MCUNNING@pct.edu>
To: <rpg@cross-check.com>; <MIDRANGE-L@midrange.com>
Sent: Friday, March 24, 2000 9:00 AM
Subject: RE: Logical Files vs. Physical Keys


> Any coding design that relys on an abnormal termination for a unique key
> error instead of doing a SETLL to see if the key exists before writing a
> record  is just bad design technique
>
> >>> rpg@cross-check.com 03/24/00 10:47AM >>>
> Yes you can use unique keyed logicals to force your physical unique,
> that is
> until the logical gets its data member removed, thus no index
> maintained,
> and some batch program updates the physical.  Now the logical member
> cannot
> be added back because of duplicate unique keys.  OOPS! some green
> program
> just caused you a big headache in scrubbing the data to remove the
> duplicates or re-assign the unique keys.  Gee what aux files have the
> key
> you need to scrub and which record goes to which?
>
> Ok that's a worst case scenario but can be prevented by putting the
> unique
> key directly on the physical.  I have had the index of a physical get
> corrupted during a power failure and the ups blowing a fuse.  It was
> real
> easy to recapture ALL the data to a new, freshly compiled, physical
> with a
> simple CPYF FROMRCD(1).  JMHO and bad experience, it is better to put
> the
> lowest level unique key on the physical for forcing the data to remain
> unique always.
>
> Christopher K. Bipes mailto:ChrisB@Cross-Check.com
> Sr. Programmer/Analyst mailto:Chris_Bipes@Yahoo.com
> CrossCheck, Inc. http://www.cross-check.com
> 6119 State Farm Drive Phone: 707 586-0551 x 1102
> Rohnert Park CA  94928 Fax: 707 586-1884
>
> If consistency is the hobgoblin of little minds, only geniuses work
> here.
> Karen Herbelin - Readers Digest 3/2000
>
>
> -----Original Message-----
> From: Kaynor@aol.com [mailto:Kaynor@aol.com]
> Sent: Thursday, March 23, 2000 7:46 PM
> To: MIDRANGE-L@midrange.com
> Subject: Logical Files vs. Physical Keys
>
>
> Chris,
> The reasons you give for keying the physical can be achieved by using
> the
> UNIQUE keyword on a logical.  Keeping your physicals unkeyed is
> arguably
> better because of the flexibility it provides.
> --Chapin Kaynor
>   Vermont
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