Execution Plans

In our last episode, I’d expanded our query to include DisplayName and Age – two columns that weren’t in our nonclustered index: Transact-SQL SELECT LastAccessDate, Id, DisplayName, Age FROM dbo.Users WHERE LastAccessDate > '2018-09-02 04:00' ORDER BY LastAccessDate; 1234 SELECT LastAccessDate, Id, DisplayName, Age  FROM dbo.Users  WHERE LastAccessDate > '2018-09-02 04:00'  ORDER BY LastAccessDate; So as a result,…

In our last episode, we added a nonclustered index, and now even though this query has a filter and an ORDER BY, it hardly did any work at all – just a lightweight index seek: Ah, index seeks – nothing better than that, right? Well, not exactly. Let’s make one tweak to the WHERE clause…

In the first post in my How to Think Like the Engine series, I started by doing a pretty simple query: But I noted that if you were following along on your computer, you might see a different execution plan. If I tweak just one thing about my SQL Server, I see a different plan:…