Statistics, An Unreliable Friend
Statistics are essential for SQL Server’s optimizer to generate a good query execution plan. A common practice is to update the statistics regularly. Although recent version of SQL Server has improved automatic statistics update with a lower threshold before automatic update is performed the larger an index grows, it is still a common problem that the statistics are not accurate when that one important and time critical query needs to run.
In this demo-packed session, I will demonstrate how statistics are used by the Query Optimizer, introduce the Ascending Key problem and talk about how SQL Server 2016 offers a great improvement compared to previous versions of SQL Server. I will also show some examples of missing statistics problems that have NOT been addressed by Microsoft, and a few different ways to address them in your code.
#statistics #tsql #performancetuning #ascendingkeyproblem