Let us continue our question of the day series with day sixteen.

What is index fragmentation ?

Index fragmentation occurs as records are added, deleted or updated over time.  As data on a page fills the page, a page split occurs moving half of the data to a new page created after all of the other pages in the table.  As you can see, when the engine is searching for data it must bounce around the pages instead of moving along contiguous pages.  As the level of fragmentation rises, query performance will degrade considerably so regular maintenance is a good idea.

Enjoy!