Date: Jan 7, 2013 4:23 PM
Author: Joe Niederberger
Subject: Re: The Great Purge of Literature

This is important so that the kids can read all the information coming forth concerning the regulation of types, quantities, time-of-day considerations, etc. of the soft drinks they consume. Besides, all the best literature is rapidly being re-worked by Hollywood into movie form with great CGI-effects added.

Now, should they be lucky and fit enough upon graduation to land a technical job, they might be delighted to find gems such as this (thanks IBM!):
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To identify which logical parent is pointed to by a logical child, the concatenated key of the logical
parent must be present
Each logical child segment must be present in the application program?s I/O area when the logical child
is initially presented for loading into the database. However, if the logical parent is in an HD database,
its concatenated key might not be written to storage when the logical child is loaded
If the logical parent is in a HISAM database, a logical child in storage must contain the concatenated
key of its logical parent. For logical child segments, you can define a special operand on the PARENT=
parameter of the SEGM statement. This operand determines whether a symbolic pointer to the logical
parent is stored as part of the logical child segment on the storage device. If PHYSICAL is specified, the
concatenated key of the logical parent is stored with each logical child segment. If VIRTUAL is specified,
only the intersection data portion of each logical child segment is stored. When a concatenated segment
is retrieved through a logical database, it contains the logical child segment, which consists of the
concatenated key of the destination parent, followed by any intersection data. In turn, this is followed
by data in the destination parent.
The concatenated key of the destination parent is returned with each concatenated segment to identify
which destination parent was retrieved. IMS gets the concatenated key from the logical child in the
concatenated segment or by constructing the concatenated key. If the destination parent is the logical
parent and its concatenated key has not been stored with the logical child, IMS constructs the
concatenated key and presents it to the application program. If the destination parent is the physical
parent, IMS must always construct its concatenated key.
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Cheers,
Joe N