Dictionary/3000 Reference Manual (32244-90001)

Appendix D 333
How HP INFORM Links Files to Generate Reports
Indirect Links
• If no files meet these two criteria, then files which contain an element to be included
in the report are considered in the following order:
MPE files
KSAM files
IMAGE detail data sets
IMAGE master data sets
If more than one file exists in the highest possible category, the file with the most elements
to be included in the report is chosen as the driving file. If there are two such files or more,
one of them is arbitrarily chosen.
• If more than one file meets these two criteria, the file which has the highest priority
link value specified (lowest positive integer) is chosen as the driving file. If more than
one of these files has the highest priority link value, then the driving file is chosen from
among them as in the above second case.
NOTE The driving file will always be read serially. It is desirable to use an MPE file
as the driving file whenever there is one which contains an element to be
included in the report; this is because HP Inform/3000 must perform a serial
read every time it accesses an MPE file to retrieve a value for a line of the
report. If the MPE file is the driving file, this serial read is done only once; if
it is not, then a serial read is done for each value of the element used to link
to the MPE file. This is not true for KSAM files or IMAGE data sets.
Hence, to ensure that a particular file is the driving file whenever an element which exists
in that file is requested for a report, add an element from that file to the group, specify the
name of that file in response to the FILE prompt, and specify a positive link value in
response to the VALUE AS A LINK prompt. The element used should be one which allows
HP Inform/3000 to link directly with other files to obtain as many elements from the group
as possible. The file you choose to specify in this manner should:
1. be an MPE file (see the NOTE earlier) if the group contains elements which only exist
in that file or if the MPE file is needed by HP Inform/3000 to link directly to other files;
2. contain the appropriate subset of data desired for reports which will be generated from
that group.
If more than one file satisfies (1) or (2), specify a link value of 1 for the file that contains the
greatest number of elements from the group, 2 for the file that contains the next greatest
number of elements from the group, and so on. Note that the more specific or limited a
group is (that is, the less varied the kinds of reports that will be generated from it are), the
more likely it is that a file which meets (2), above, can be specified.
EXAMPLE 1 at the end of this appendix demonstrates choosing a file which meets (1),
above. EXAMPLE 2 demonstrates choosing a file which meets (2), above.