Paul White (@SQL_Kiwi) is an independent SQL Server technical consultant with 25 years experience, specializing in performance tuning the SQL Server Core Engine, and is well known for his expertise in execution plans, the query processor, and the query optimizer. Currently living in New Zealand, Paul writes the SQL Server internals blog Page Free Space.
Over the years, Paul has worked internationally on a number of high-volume critical systems where ultimate performance and reliability were the primary goals. A SQL Server MVP from 2011 to 2022, he contributes regularly to a range of web sites and forums, including Database Administrators Stack Exchange. Paul has also spoken at a variety of user groups and community events such as SQL Saturdays and the annual SQL Pass Summit.
Paul White goes deep on grouped aggregation pushdown, and explains examples where this optimization is unsuccessful or simply not attempted, using the undocumented command DBCC CSINDEX.
Paul White explains why the IGNORE_DUP_KEY index option on a clustered index can result in much poorer performance than for a nonclustered unique index.
