In the conclusion of his series on grouping and aggregation costs, Itzik Ben-Gan reveals some of the math behind seek vs. scan decisions.
In the fourth installment of his series on optimization thresholds, Itzik Ben-Gan looks at how SQL Server applies costs to parallel operations.
Itzik Ben-Gan dissects the Hash Match (Aggregate) algorithm in his latest post in a series on SQL Server optimization thresholds.
Continuing his series on optimization thresholds, Itzik Ben-Gan dives into the costs behind stream aggregates when the data needs to be sorted first.
For his first post on SQLPerformance.com, Itzik Ben-Gan shows you how to reverse engineer optimizer costing for a Stream Aggregate operator.
The next release of Microsoft SQL Server, announced as SQL Server 2017, is available for download in CTP2 at http://tinyurl.com/SQLvNextLinux and offers many cool new features. One set of features that I really want to focus on is adaptive query processing. These new features speed processing of workloads, especially those that have historically been the […]
Paul White (@SQL_Kiwi) takes you on an optimizer journey, exploring how SQL Server comes up with cardinality estimates for COUNT queries.
I had the pleasure to spend some time with my old friend Mark Souza, a general manager in the Data Platform team at Microsoft, while speaking at the SQL Saturday event in Dublin, Ireland last summer. Now keep in mind that Mark and I have known each other since the 1990s when SQL Server was […]
Paul White (@SQL_Kiwi) shows how an update may fail when a partition has some data on a read-only filegroup, and explains several workarounds.
Aaron Bertrand (@AaronBertrand) highlights a handful of Connect items aimed at improving SQL Server showplan diagnostics and query tuning in general.
Paul White (@SQL_Kiwi) rolls up his sleeves in his usual way, showing off the debugger several times while explaining the internals of SQL Server sorts.