From the course: Migrating COBOL Apps

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The buried update

The buried update - COBOL Tutorial

From the course: Migrating COBOL Apps

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The buried update

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- Legacy COBOL programs often make coding compromises, in order to boost their performance. For example, advice in one COBOL reference manual, includes the statement. Sequential file users should code for performance by retaining several records at a time. Performance is optimal if the number of records retained, is a multiple of the blocking factor, and the execution of the retain statement is synchronized with logical block boundaries. However, retaining records longer, increases the risk of other programs trying to concurrently access the file. Which in turn may cause programs to lock up. While this may not be a problem, in a legacy batch environment, problems can occur after migrating to a more contemporary environment. The first problem is known as the buried update. Which occurs when one program updates a record, but the update is overwritten when a second program, which also has a copy of the original record,…

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