ACCG358 Lecture Notes - Lecture 8: Virtual Storage Access Method, Unique Key, Database Design
29 Jun 2019
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Document Summary
The way data is organized i. e. physically arranged on the secondary storage device. Techniques used to access data i. e. locate records and to navigate through the database or file. Records in a specific sequence by key field in the contiguous storage space. The application reads from the start in sequence. Not the most efficient approach when only reading a small portion of the file. Record cannot be accessed directly must go through sequence. No consideration of physical proximity to other related records. Organization of index file could be sequential or random. Maintenance is easier than sequential i. e. adding records. Rapid search capability o uses storage space on disk more efficiently and searching is quicker. Sequential records are better when large portions of the record are being modified. Three components: indexes, prime data storage area, overflow area. This could cause slower search times as all three areas may need to be searched.
