Statistical Legacy
A client question that I get quite a bit is around why queries in production get a bad query plan that queries in dev, QA, or staging don’t get is typically answered by looking at statistics.
Primarily, it’s …
Category: Cardinality
Local Variables vs Forced Parameterization In SQL Server Queries
Questions, Arise!
I think it was sometime in the last century that I mentioned I often recommend folks turn on Forced Parameterization in order to deal with poorly formed application queries that send literal rather than parameterized values to SQL …
One Thing The “New” Cardinality Estimator Does Better In SQL Server
Or “Default”, If That’s Your Kink
Look, I’m not saying there’s only one thing that the “Default” cardinality estimator does better than the “Legacy” cardinality estimator. All I’m saying is that this is one thing that I think it does …
Starting SQL: What’s The Difference Between Parameters And Local Variables In SQL Server?
Parameter Positive
There are many good reasons to parameterize a query, but there are also trade-offs. There’s no such thing as a free parameter, as they say.
In this post, we’re going to discuss what is and isn’t a parameter, …
How Are Table Variables Different In SQL Server 2019?
WallaWallaBingBang
Going Further
If this is the kind of SQL Server stuff you love learning about, you’ll love my training. I’m offering a 75% discount on to my blog readers if you click from here. I’m also available for …
How Bad Cardinality Estimates Lead To Bad Query Plan Choices
Let’s Run A Cruddy Query
We’ve got no supporting indexes right now. That’s fine.
The optimizer is used to not having helpful indexes. It can figure things out.
SELECT p.*
FROM dbo.Posts AS p
JOIN dbo.Votes AS v
ON p.Id … Why Some SQL Server Date Functions Get Better Cardinality Estimates
Date Debate
Searching dates is a common enough task. There are, of course, good and bad ways to do this.
Aaron Bertrand’s article, Bad habits to kick: mis-handling date / range queries, is a good place to start to …
SQL Server Join Containment for the Common Man
Lots of smart people have written about join containment, but none of the explanations really made sense to me. I felt like a student memorizing definitions for a test. Sure, I could tell you the definitions of base and …