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read record. Notice that with this processing mechanism, if only a single record
has to be processed, on an average, about half the file has to be searched to
retrieve the desired record for processing. Thus, sequential files are not suitable for
applications that process only one or a few records at a time.
Sequential file organization is the most efficient and economical file organization
in case of applications in which there is a large number of file records to be
updated at regularly scheduled intervals. That is, when the activity ratio (the ratio
of the total number of records in transaction file and the total number of records in
master file) is very high. This can be ensured by using the idea of batch
processing, in which transactions of a similar type are accumulated into batches,
then these batches are sorted into sequence with respect to the key field values of
the records, and then the entire batch of records is processed in a single pass
through the file. Applications such as payroll processing and monthly bill
processing are processed in this manner.
Advantages of Sequential Files
Sequential files typically have the following advantages:
1. They are conceptually simple to understand and use.
2. They are also easy to organize and maintain.
3. They need relatively inexpensive I/O media and devices for their storage and
4. They are most efficient and economical to use in applications in which the
activity ratio is high (me records are changed during update runs).
Disadvantages of Sequential Files Sequential files typically have the following disadvantages:
1. They prove to be very inefficient and uneconomical for applications in which
the activity ration is very low.
2. Since an entire sequential file may need to be read just to retrieve and update
few records, accumulation of transactions into batches is recommended before
processing them. Hence the use of sequential files is limited to a batch processing
3. Because of the need to accumulate transactions into batches before processing
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This document was uploaded on 04/07/2014.
- Spring '14