4. Storage and Retrieval

In this lesson we are going to look at storage and retrieval, in particular the role of the database management systems (DBMS) including –  

  • the role of a DBMS in handling access to a database  
  • the independence of data from the DBMS 
  • direct and sequential access of data 
  • on-line and off-line storage 
  • centralised and distributed databases 
  • storage media including: 
    1. hard discs 
    2. CD-ROMS  
    3. cartridge and tape 
    4. encryption and decryption 
    5. backup and security procedures 

We will also learn how to calculate the storage requirements for a given number of records (given a data dictionary for a database)

Objectives

  • H4.1  proposes and justifies ways in which information systems will meet emerging needs 
  • H5.2  assesses the ethical implications of selecting and using specific resources and tools, recommends and justifies the choices 
  • H6.1  analyses situations, identifies needs, proposes and then develops solutions 
  • H7.1  implements and explains effective management techniques

Introduction

Storage and retrieval of data occurs within all information systems, however it is particularly critical in regard to maintaining large data stores.  

Examples of large data stores include relational databases accessed using a DBMS and also web pages and other online files accessed via the Internet.  

The performance data centred systems is dependent of the efficiency and security of storage and retrieval hardware that physically maintains and moves data and also the software that controls and directs this hardware.