Dave Ballantyne
clearskysql.co.uk
Dave is a freelance SQL Server database architect / designer / developer / consultant and lives near London, England. He is a regular speaker at UK and European events and user groups.
SQLBits 2015
Estimation and Statistics : The Basis of query optimization
This will be a deep dive into how the optimizer makes its decisions to give you a plan, the things that can go wrong and how you can have influence over these choices.
At the heart of SQL Server is the cost based optimizer. Stop and think about that a minute, the optimizer attempts to give the “best plan” based on the cost of the work undertaken.
How does it know the cost of the work before its done the work ? This isn’t a conundrum, it doesn’t. It estimates! How does it estimate ? That is statistics.
This will be a deep dive into how the optimizer makes its decisions to give you a plan, the things that can go wrong and how you can have influence over these choices.
How does it know the cost of the work before its done the work ? This isn’t a conundrum, it doesn’t. It estimates! How does it estimate ? That is statistics.
This will be a deep dive into how the optimizer makes its decisions to give you a plan, the things that can go wrong and how you can have influence over these choices.