title: What is a SPATIAL INDEX and when should I use it?
body: <p>Like most of the average PHP web developers I use MySql as a RDBMS. MySql (as other RDBMS also) offers SPATIAL INDEX features, but I'm don't get it very well. I have googled for it but didn't find clear real world examples to clarify my bad knowledge about it.</p>
  
  <p>Could someone explain me a little bit what is a SPATIAL INDEX and when should I use it?</p>