Brent Ozar notices a difference:
Forever now, FOREVER, it’s been a standard thing where I can say, “When you’re measuring storage performance during index and query tuning, you should always use logical reads, not physical reads, because logical reads are repeatable, and physical reads aren’t. Physical reads can change based on what’s in cache, what other queries are running at the time, your SQL Server edition, and whether you’re getting read-ahead reads. Logical reads just reflect exactly the number of pages read, no matter where the data came from (storage or cache), so as long as that number goes down, you’re doing a good job.”
But this is not always the case, as Brent demonstrates.
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