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File Systems and Database Systems

File Systems and Database Systems. Outline. Roots of the Database System: File System Problems with File System Data Management Database System. 1. File System. Case of a File. A manager of any small organization was able to keep track of necessary data using a manual file system.

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File Systems and Database Systems

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  1. File Systems and Database Systems

  2. Outline • Roots of the Database System: File System • Problems with File System Data Management • Database System

  3. 1 File System

  4. Case of a File • A manager of any small organization was able to keep track of necessary data using a manual file system. • A MANUAL FILE SYSTEM consist mainly of a collection of file folders, properly tagged(or labeled) and kept in a filing cabinet.

  5. Manager’s File Cabinet • Personnel • Technical Technical: Data pertaining to only those people whose duties were properly classified as TECHNICAL. • Sales • Admin

  6. Doing well for a while • At first, data collection was relatively small and an organization’s manager had few reporting requirements, the manual system served its role well as a data storehouse.

  7. But the organization grew… • However, as the organization grew and the storing requirements became more complex, keeping track of the data became more difficulty. • Retrieval was time consuming and cumbersome, thus, it is unlikely that the data could generate useful information.

  8. Consider these questions: • How many products sold during the past week, month, quarter or year? • What is the current daily, weekly, quarterly or yearly sales peso volume? • Did we gain more this month compared to last month’s sales?

  9. The Data Processing Specialist • Thus, the manager needs to hire a new kind of professional: a Data Processing (DP) Specialist. • The task is to be able to manage and process data. Process means to draw out useful information from the data. • The DP creates file structures, the software and design reports from the data.

  10. Customers Alfred Ramos Phone: 0927-565-4896 Address: #42 Rodeo St. Macabalan, CDO ZIP: 9000 Agent Name: Leah Vidal Phone: 0927-565-4444 Insurance Type: T1 Amount: P500.00 Renewal Date: December 12, 2012

  11. Customer File

  12. Consider these questions: • How many agents do we have? • Sales per agent?

  13. Singular File System • Each department has their own file system. • It is not the concern of the Customer’s Department. • The Customer’s Department must create their own file system.

  14. File Mgmt Program File Mgmt Program CUSTOMER FILE SALES FILE AGENT FILE Personnel Dept Sales Dept File Report Program File Report Program

  15. FILE SYSTEM PROGRAM FILE STRUCTURE

  16. 2 Problems with File System Data Management

  17. Task of a Filing System • Storing Data • Saving and Organizing • Updating Data (Edit or Delete) • Retrieving Data • Processing Data to Reports

  18. File Systems are inefficient with the three task

  19. 1. Data Retrieval Task • 3GL Languages vs 4GL Languages • 3 GL : • BASIC,C++, Fortran,Cobol • Programmer to specify what must be done and how it is to be done • 4 GL : • SQL • Programmers to specify what must be done without specifying how it must be done. • Save an average of 60% of lines of code

  20. 3GL vs 4GL • It requires extensive programming • There is no ad hoc query capabilities • System Administration can be complex and difficulty • It is difficult to make changes to existing structure • Security features are likely to be inadequate

  21. 2. Data Storing and Organizing STRUCTURAL • Structural Dependence: If the file structure changes, the file system program must adapt. • Structural Independence: the file system program need not to change if the file structure changes

  22. DATA • Data Dependence: Data access programs are subject to change when any of the file’s data storage characteristics change. • Data Independence: possible to make changes in the data storage characteristics without affecting the application program’s ability to access data.

  23. 2. Data Updating • Data Redundancy • Premise: data should be accurate (no data inconsistencies) and verifiable (always yield consistent results) • Data anomalies – develops when all of the required changes in the redundant data are not made successful • Update Anomalies – not all are updated • Insertion Anomalies • Deletion anomalies -

  24. 3 Database Systems

  25. What is a DATABASE? • The database is consist of logically related data stored in a single logical data storeroom or repository.

  26. Employees File System Customers Inventory Sales Accounting Department

  27. Hardware • Software • People • Procedures • Structures

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