Sunday January 21st 2018




Difference between Index and Primary Key

This post is on very important topic – “Difference between Index and Key” and is explained in very clear and easy terms by Michael J. Hernandez in his book Database Design for Mer Mortals on page 61. We are emphasizing in this post that most of the IT books lacks clarity or makes concepts more complicated resultantly negative impact on the productivity and probably should look at the above book how it explains an important topic.

An index is a structure RDBMS provides to improves the data processing. Your particular RDBMS program will determine how the index works and how you use it. How index has absolutely nothing to do with logical data structure and people often confuse it with term key.

Index and key are just two more terms that are widely and frequently misused throughout the database industry and in numerous database related publications – you’ll always know the difference between the two if you remember that keys are logical structures you use to identify records within a table and indexes are physical structures you use to optimize data processing.