How to Think Like the SQL Server Engine

Earlier in this series, we ran a query with ORDER BY, and we realized that it was CPU-intensive work that tripled the cost of the query: Now, let’s run that query a bunch of times. In SSMS, you can add numbers after the GO, and SSMS will run your query a number of times. I’ll…

In our last post, we ran a query with an ORDER BY, but we only got one column in the SELECT: Transact-SQL SELECT Id FROM dbo.Users WHERE LastAccessDate > '2014/07/01' ORDER BY LastAccessDate; 1234 SELECT Id   FROM dbo.Users   WHERE LastAccessDate > '2014/07/01'   ORDER BY LastAccessDate; The estimated cost was about $18 Query Bucks because SQL…

We started out the How to Think Like the Engine series with a simple query with a WHERE clause: Now let’s add an ORDER BY: Transact-SQL SELECT Id FROM dbo.Users WHERE LastAccessDate > '2014/07/01' ORDER BY LastAccessDate; 1234 SELECT Id   FROM dbo.Users   WHERE LastAccessDate > '2014/07/01'   ORDER BY LastAccessDate; Here’s the updated plan – note…

You’re a developer or a DBA, and you’re comfortable writing queries to get the data you need. You’re much less comfortable trying to design the right indexes for your database server. In the next several posts, you’ll learn: The differences between clustered and nonclustered indexes How (and when) to make a covering index The basics…