Your SlideShare is downloading. ×
File organization
Upcoming SlideShare
Loading in...5

Thanks for flagging this SlideShare!

Oops! An error has occurred.

Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

File organization


Published on

Published in: Education, Technology, Business

No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

No notes for slide


    • Serial
    • Sequential
    • Indexed Sequential
    • Direct Access /Random Access
  • 3. Serial File Organization
    • A collection of records
    • No particular sequence
    • Cannot be used as master
    • Used as temporary transaction file
    • Records stored in the order received
  • 4. Sequential File Organization
    • A collection of records
    • Stored in key sequence
    • Adding/deleting record requires making new file
    • Used as master files
  • 5. Sequential file
  • 6. Advantages
    • Simple file design
    • Very efficient when most of the records must be processed e.g. Payroll
    • Very efficient if the data has a natural order
    • Can be stored on inexpensive devices like magnetic tape.
  • 7. Disadvantages
    • Entire file must be processed even if a single record is to be searched.
    • Transactions have to be sorted before processing
    • Overall processing is slow
  • 8. Direct (Random) File Organization
    • Records are read directly from or written on to the file.
    • The records are stored at known address.
    • Address is calculated by applying a mathematical function to the key field.
  • 9. Direct (Random) File Organization
    • A random file would have to be stored on a direct access backing storage medium e.g. magnetic disc, CD, DVD
    • Example : Any information retrieval system. Eg Train timetable system.
  • 10. Advantages
    • Any record can be directly accessed.
    • Speed of record processing is very fast.
    • Up-to-date file because of online updating.
    • Concurrent processing is possible.
  • 11. Disadvantages
    • More complex than sequential
    • Does not fully use memory locations
    • More security and backup problems
  • 12. Indexed sequential file
    • Each record of a file has a key field which uniquely identifies that record.
    • An index consists of keys and addresses .
    • An indexed sequential file is a sequential file (i.e. sorted into order of a key field) which has an index .
    • A full index to a file is one in which there is an entry for every record.
  • 13. Indexed sequential file
  • 14. Indexed sequential file
    • Indexed sequential files are important for applications where data needs to be accessed.....
      • sequentially
      • randomly using the index.
  • 15. Indexed sequential file
    • An indexed sequential file can only be stored on a random access device e.g. magnetic disc, CD.
  • 16. Advantages
    • Provides flexibility for users who need both type of accesses with the same file
    • Faster than sequential
  • 17. Disadvantages
    • Extra storage space for the index is required
  • 18. Batch Processing
    • Batch processing is updating master files periodically to reflect all transactions that occurred during a given time period.
    • The master file is updated at set times or whenever a manageable number of transactions are gathered.
    • Transaction data can either be entered as a batch or as each transaction occurs.
  • 19. Batch Processing Master file Group source documents into batches.
  • 20. On-line Batch Processing Master file Enter transactions into system as they occur.
  • 21. On-line, Real-Time Processing
    • In on-line, real-time processing, the computer captures data electronically,...
      • edits it for accuracy and completeness, and...
      • immediately processes it.
    • The computer also processes information requests from users.
  • 22. On-line, Real-Time Processing Master file Enter transactions into system as they occur.
  • 23. Advantages of Each Method
    • The main advantage of batch processing was efficiency in processing.
    • On-line data entry is more accurate than periodic batch input because the system can refuse incomplete of erroneous entries.
    • Real-time processing ensures that the information in master files is always current.