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Section
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Page
20
40
I
60
01
File Processing
Before the file design is finally determined, the run
time and associated costs should be calculated for
the entire system. The results must be evaluated
to determine whether the original design objectives
have been met. If the system is I/O-limited (that
is, if
I/o
time exceeds prooess time), the following
approaches may be considered:
•
Create a second master file splitting awayfrom
the main master file those fields not required on the
primary runs. For example, name and address
records could be kept in
a
separate name and address
file. This new file would be used perhaps only as
output documents are printed.
•
Extract from the master file the active records
for processing. This method is useful if the ratio of
active master records to total master records is
very low.
•
Increase the number of input buffers.
If
the
activity rate is low and processing time per hit is
high, more process time can be overlapped
if
the
input is queued in additional buffers. Ifprocesstime
requires 250 milliseconds while an input area can
be filled in 50 milliseconds, there will be 200 milli-
seconds of unoverlapped process time per hit, with
two input areas.
If
the number of input areas were
increased to four, only 100 milliseconds would not
be overlapped.
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