Articles tagged

10 October 2011
10 October 2011

Complete Showplan Operators

Fabiano Amorim has taken the time to really drill into the behavior of a small set of execution plan operators in an effort to explain the optimizer's behavior. He's explored why things happen, how you can change them, positively or negatively, and he's done it all in an approachable style.… Read more
10 September 2010
10 September 2010

Showplan Operator of the Week – Stream Aggregate

Fabiano continues his mission to explain the Query Optimiser in practical terms, describing, one week at a time, all the major Showplan Operators used by SQL Server's Query Optimiser to build the Query Plan. He discusses the Stream Aggregate function and shows how easy it is to get performance gains in GROUP BY clauses by choosing the right index.… Read more
07 May 2010
07 May 2010

Showplan Operator of the Week – BookMark/Key Lookup

Fabiano continues in his mission to describe the major Showplan Operators used by SQL Server's Query Optimiser. This week he meets a star, the Key Lookup, a stalwart performer, but most famous for its role in ill-performing queries where an index does not 'cover' the data required to execute the query. If you understand why, and in what circumstances, key lookups are slow, it helps greatly with optimising query performance. … Read more