Blog posts tagged with 'index':

Covering indices

Date: 22 Dec 2009
Tags: [ covering ]  [ index ]  [ MySQL

It’s almost to easy to use a SELECT * FROM query in your code. First of all, you instantly get all the fields from your database so you don’t have to worry about changing your queries when you decide to use other fields (in case you don’t use a DAL). However, there are some drawbacks on a SELECT * method,.. the most famous one: it takes more time to retrieve all fields instead of the fields you actually use.. but that’s NOT the most important reason why you should not SELECT * FROM queries..

The main reason? Covering indices…