1 / 15

Predecessor to the Database: Traditional File Processing

Predecessor to the Database: Traditional File Processing. Records are stored in files. Programs are customized to process the data. File Structure. Bit 1 0r 0 Byte 8 bits (number, character, letter, symbol) Field Grouping of characters into a word or number Record

bona
Download Presentation

Predecessor to the Database: Traditional File Processing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Predecessor to the Database: Traditional File Processing • Records are stored in files. • Programs are customized to process the data

  2. File Structure • Bit • 1 0r 0 • Byte • 8 bits (number, character, letter, symbol) • Field • Grouping of characters into a word or number • Record • A group of related fields • File • A group of records of the same type • Database • A group of related files

  3. File Environments • Record / Entity • A collection of fields that contain information concerning a specific thing or event • field / attribute • a piece of information that further describes the record • key field (primary key) = unique identifier • attribute(s) that uniquely identifies an entity • Example = social security number, course number

  4. How are the records stored and accessed?

  5. Accessing records • Stored on secondary storage devices • Storage methods • sequential file storage / access • records retrieved in the same physical sequence in which they are stored • Normally uses magnetic tape • Think of your cassette tapes • direct file storage / access • access records in any sequence • Must know the key of the record • Stored on magnetic / optical disks

  6. Direct Access Methods • Direct File Access Method • key of the record is mathematically transformed into the actual address of the record (hashing) • Go directly to the address to retrieve the record • ISAM • indexed sequential access method • records are stored sequentially on DASD • retrieved through the use of indexes that store the cylinder / track of the record • cylinder / track is then searched sequentially for the record you want

  7. Effect of Data Organization on Processing • speed of storage • How long does it take to store the records • speed of retrieval • How long does it take to retrieve the records • speed of processing • Processing time is suspended while the CPU waits for the record to be retrieved

  8. Traditional File Processing • Uses transaction processing • A transaction is the record of an event. • Requires a Master File, and many transactions files • Master File – “permanent” information • Transaction file – contains information relevant to the most recent transactions.

  9. Transaction Processing Master File Transaction File

  10. Traditional Files

  11. Limitations of File Processing • Separated and Isolated Data • Data Duplication (i.e. data integrity) and Confusion • Application Program Dependency • Incompatible Files • Difficult to Represent Users’ Perspectives of Data • Lack of Data Sharing and Availability

  12. Advantages of Database Processing • Integrated Data • Less Duplication of Data • Program/Data Independence • Easier Representation of Users’ View of Data • Restrict Unauthorized Access • Backup and Recovery

More Related