Records and Blocks

Question: What is the difference between Records and Blocks?

Answer: Blocks are physical records written to the storage device as a single record. With fixed length records the operating system knows how long each physical record / block will be. With variable elngth records the record length is stored on the front of the record.

Records within a block are virtual records. The program will red and write data in blocks and then the program will break the block up into the individual records for use by the program.

As each physical record has certain overheads in the amount of storage space required and read and write time, grouping records into blocks saves on both space and processing time.


This article written by Stephen Chapman, Felgall Pty Ltd.

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