Paul White (@SQL_Kiwi) digs into row goals as he explains some interesting and inconsistent behavior with UNION ALL.
Paul White (@SQL_Kiwi) takes you on an optimizer journey, exploring how SQL Server comes up with cardinality estimates for COUNT queries.
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.