Short answer: the SQL Server optimizer will know that the table was truncated, but statistics might not update when you expect.
For the long answer, let’s walk through an example using the WideWorldImporters sample database.
Whether I’m working as a DBA, a consultant, a teacher, or just answering questions in my inbox, I always end up needing a script to inspect statistics one way or another.
Here are some freshly written scripts for a classic DBA question: what’s going on in my stats?
The bigger your indexes are, the harder your index maintenance falls. Is it better to rebuild big indexes? Or should you reorganize?
What tools in SQL Server will notify you about blocking and help track the queries behind your toughest blocking and deadlocking problems?
If you haven’t checked out Microsoft’s new WideWorldImporters sample database for 2016, it’s a pretty cool new little database. The database makes it easy to play around with new 2016 features, and it even ships with some cool little executables to run inserts in the “workload-drivers” folder.
Unique constraints and unique nonclustered indexes have a lot in common: unique constraints are implemented with a unique index behind the scenes.
While unique nonclustered indexes have a couple of additional features, I can still think of a scenario where it might be best to use unique constraints.
This is one of those little details that confused me a ton when I was first working with execution plans.
One problem with learning to work with plans is that there’s just SO MUCH to look at. And it’s a bit spread out. So, even when looking at a single tooltip, things can be confusing.
Let’s talk about the nested loop operator, who can be particularly weird to understand.
Copyright (c) 2025, Catalyze SQL, LLC; all rights reserved. Opinions expressed on this site are solely those of Kendra Little of Catalyze SQL, LLC. Content policy: Short excerpts of blog posts (3 sentences) may be republished, but longer excerpts and artwork cannot be shared without explicit permission.