Is Read Uncommitted (NOLOCK) An Optimistic Or Pessimistic Isolation Level?

Poll Worker


I ran a Twitter poll recently, because as I was writing another blog post, I wasn’t quite sure how to group uncommitted/nolock between pessimistic or optimistic isolation levels.

On the one hand, locking and blocking does still come into play with them. anyone who has seen locking on schema stability can attest to that. On the other hand, they will read just about anything you want. That’s sort of optimistic in spirit, but maybe not in letter.

Most of you kind folks out there called it optimistic, though some others had more colorful language to describe it:

At the end of the day, it’s probably not the right isolation to use, no matter what you choose to call it.

Thanks for reading!



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