This problem is known as collision when a collision

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Unformatted text preview: equential processing precludes the possibility of up-to-the-minute data. 4. Sequential processing requires the files to be sorted before processing. That is, both the transaction and master files must be sorted and placed in the same sequence prior to processing. 5. Sequential processing often leads to data redundancy problem, since the same data may be stored in several files sequenced on different .keys. Direct Files Many applications require up-to-the-minute timeliness of data. The users of such applications cannot afford to wait for the transactions to be accumulated in batches and then processed together. Such applications require a transaction to be processed immediately as and when it occurs. A few examples of such applications are airline or railway reservation systems, teller facility in banking applications, systems for enquiring whether a certain item is in stock in a store, etc. Note that the activity ratio is very low in these applications since only one transaction is processed at a time. Hence the use of sequential files for such applications proves to be very inefficient and uneconomical. The use of direct/random files is recommended for such applications because in a direct/random file organization, the desired record pertaining to the current transaction at hand can be directly located by its key field value without having to search through a sequence of other records. For example, when a passenger makes a reservation request for a particular train on a particular date, the computer can directly access the record for the train and update its seats position for that date. Obviously, direct/random files need to be stored on a direct access storage device to enable direct access of records. The principal storage medium for direct/random files is magnetic/optical disk. The obvious question that arises now is how are the records in a direct file physically organized so that it becomes possible to directly access a particular record, given its key field value, from a number of records store...
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This document was uploaded on 04/07/2014.

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