On Thu, 6 Nov 1997 21:30:05 -0700, John Pearce <[log in to unmask]>
writes:

>I seem to recall the technique I'm looking for did something like putting
>the single character in front of an existing key for each record and used
>that compound item as the key.  That helped out with the chain length at
>the expense of having more data in the key than really necessary.  I'm not
>sure how the retrieval worked although I can guess it involved a
sequential
>read of the automatic master looking at the first character of the data.

This is how a former employer of mine (a software vendor) designed their 
system.  But the problem they were solving was making the data plant 
specific.  What they did was prefix the key value (say, the product 
number, for instance) with a one character code that indicated which 
plant the product number "belonged" to.  They had a special value for 
the code (a zero, IIRC) which indicated that the record was for all 
plants.

To retrieve a record you prepended the plant code to the key value and 
did the retrieval.  If you don't know the key value, or want all key 
values for a specific plant code, then yes, you have to do a serial 
read of the data set.

Contact me directly if you want more data.

Jim Phillips                            Manager of Information Systems
E-Mail: [log in to unmask]      Therm-O-Link, Inc.
Phone: (330) 527-2124                   P. O. Box 285
  Fax: (330) 527-2123                   Garrettsville, Ohio  44231