Introducing the Query Store

The requirement to track query performance statistics over time has been a longtime request by SQL Database Engine users because it unlocks the ability to go back in time and understand trends and point-in-time occurrences. Maybe a point-in-time issue with the database caused our company website to glitch, or a critical application slows down periodically without a predictable pattern, or we noticed that part of our workload is much slower after an upgrade to a new version of the SQL Database Engine. Barring any hardware problems, all these scenarios can usually be boiled down to one common cause – query plan optimization choices. This led to the creation of the Query Store – an effective flight recorder for our databases that’s available in SQL Server (starting with SQL Server 2016) and Azure SQL Database, including Managed Instance.

Recall what we discussed on the process of query optimization in Chapter 1, Understanding Query Processing...