At 02:30 PM 10/30/97 -0800, [log in to unmask]
wrote (privately):

>> Any file on which you want to create a B-tree must
>> first be given a new automatic master which will add to the overhead on
>> every new record added.
>
>Huh?
>
>My understanding (such as it is) of the new Image B-tree feature is that
>(1) it goes against only Master sets, and (2) it involves the creation
>of only a NM KSAM file.
>
>Thus, I don't see where the auto master mentioned above comes in at all.

Since Glenn raises issues that I can't altogether answer, I am sending a
copy his message to the list.

Many people keep data in detail datasets with automatic masters, rather
than in manual masters so that it can be accessed by other keys.  If you
want to add a B-tree to this dataset on, say, a name field, then this field
must be given its own automatic master in order to access it using a
B-tree.  This adds one extra level of updating and searching as compared to
a B-tree constructed directly on the detail data set.

From another point of view, if you want more than one B-tree on a
particular dataset, it must be a detail and there must be a master
(automatic or manual) for each index.

If my understanding on this is wrong, please correct me.

John D. Alleyn-Day
Alleyn-Day International
408-286-6421   408-286-6474 (Fax)
[log in to unmask]       http://www.Alleyn-Day.com