Blog posts tagged with 'covering':
Covering indices
Date: 22 Dec 2009Tags: [ 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…