Comments on: Data Page Count Influence on the Query Execution Plan

By: Joseph Sack

Joseph Sack — Tue, 22 Oct 2013 13:07:39 +0000

In reply to Neeraj.

Hi Neeraj,

Fragmentation can inflate the page count – and the query optimizer looks at page count for some operators, so yes. But the QO doesn’t look directly at fragmentation as part of the set of properties considered…

Joe

By: Neeraj

Neeraj — Tue, 22 Oct 2013 06:48:29 +0000

thanks the the post,
i have a question here
does fragmentation also affect the query plan?

By: Joseph Sack

Joseph Sack — Mon, 15 Apr 2013 13:34:53 +0000

In reply to Lonny Niederstadt. Thanks Lonny. That's a good list of considerations. And I think the overall takeaway is that fragmentation doesn't just impact I/O and memory, but also impacts plan choices.

By: Lonny Niederstadt

Lonny Niederstadt — Mon, 15 Apr 2013 02:49:19 +0000

Good stuff. So, when an index has significantly less than expected use, evaluate: fragmentation, fit to query candidates(key columns/included columns), and page count comparison to the alternative path selected by the plan?