Detecting Plan Regression in SQL Server Using Query Store
Bad code rarely begins the cascade of most SQL Server performance problems. Typically, it begins with something that is much harder to explain: a query that had been running fine for weeks starts slowing down even when no apparent change occurs. There were no deployments, no schema changes, no new features, but just slower, and users started complaining. The dashboards still all look mostly fine, the first reaction is usually: "What is different?" The most frustrating part is that from the application side, nothing changed.
The Query Didn’t Change, but Something Else Did
From the application perspective, everything still looks the same. Same request, same stored procedure, same parameters, same application code. Nobody touched anything, so naturally, people expect the database to behave the same way, too. Now, this is not really how SQL Server works.
Behind the scenes, SQL Server is constantly reevaluating the best way to run a...
Copyright of this story solely belongs to hackernoon.com. To see the full text click HERE
