2 - Data Organization

An indexed field is a fiield in a fi f random

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Unformatted text preview: processing: The file can be processed in an order different than the processed in an order different than the physical order. record used for identifying/ locating records records from a group of records BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo 21 BUSI 335 22 Copyright © 2009-10 Y.M. Cheung, William Tan and Carson Woo Indexes (Good or Bad) (Good or Bad) For discussion … discussion • Will it be useful to index the “sex” field for the • Disadvantages following table? Why and why not? Wh – Two data access: Before accessing the actual record, the index file need to be accessed. Emp# FirstName LastName Sex Phone Salary – Additional storage space: Space is required for the indexes 24879435 Mary 89340945 Joe Watson M (416) 902-7943 $40,000 – Processing time: Search for the index file is time: for the index file is required in order to locate the address of the record. 49220894 Anna Johnson F (250) 235-9099 $45,000 94325765 John Smith M (604) 222-7698 $30,000 62834948 Susan Wood F (905 )823-7948 $55,000 98430917 98430917 Ken Jackson M (780) 209-4859 $50,000 209 – Additional Processing: When the data are changed, special processing will be required to update the indexes (especially if there is more than one index) one index). BUSI 335 Copyright © 2009-10 Y.M. Cheung, William Tan and...
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