Today we will understand indexes which we have been reading and listening for a long time. Whenever we query so mething, and it runs slow we hear many steps of performance tuning. And “Use Proper Index” will always make the list. What is an Index? Google says . Lets start our analysis!! Alphabetical it says. What is alphabetical? So rted? Yes. Index is so me so rt of so rting. :) “Reference to pages on which they are mentioned”. But we are not dealing with books here. We are dealing with data. lets say our data is stored as pages on computer . ( Don’t want to assume? Want to see how data is stored in memory? Check this link ) . Now index is so me so rted object which holds reference to the data stored either in-memory or disk. What benefit I get on creating on extra object which consumes my computer re so urces?? Well... lets go into our classical dictionary example. 1 st question.. Do I need indexes always? I gave you a page with words and meanings. A nano