Introduction To Data Management And File Structures

Introduction to Data Management and File management Most computers are used for data processing, as a big growth area in the "information age" Data processing from a computer science perspective: Storage of data Organization of data Access to data Processing of data Data Structures vs File Structures Both involve: Representation of Data Operations for accessing data Difference: Data structures: deal with data in the main memory File structures: deal with the data in the secondary storage Main Memory-MM ast small volatile, i. e. ata is lost during power failures. Secondary Storage-SS big (because it is cheap) stable (non-volatile) i. e. data is not lost during power failures slow (10,000 times slower than MM) How fast is the main memory? Typical time for getting info from: Main memory: —10 nanosec = 10 x 10-9 sec Hard disks: —10 milisec = 10 x 10-3 sec An analogy keeping same time proportion as above: seconds versus weeks Goal of the file structures What is performance Time Minimize the number of trips to the SS in order to get desired information Group the SS.

Memory Balance the memory size and the time How to improve performance Use the right file structure Understand the advantages disadvantages of alternative methods Metrics used to measure efficiency and effectiveness of a File structure-I simplicity, reliability, time complexities, space complexities, scalability, programmability, and maintainability. *Note that the domains of the efficiency and effectiveness concerns rely on time and pace complexity more than any other factor.

Metrics used to measure efficiency and effectiveness of a File structure-2 The file structures involve two domains: hardware and software. Hardware primarily involves the physical characteristics of the storage medium. Software involves the data structures used to manipulate the files and methods or algorithms to deal with these structures. The physical characteristics of the hardware together with data structures and the algorithms are used to predict the efficiency of file operations.