SQLCAT.Com – eBook Downloads

As of September 1, 2013 we decided to remove SQLCAT.COM site and use MSDN as the primary vehicle to post new SQL Server content. This was done to minimize reader confusion and to streamline content publication.  MSDN SQLCAT blogs already includes most SQLCAT.COM Content and will continue to be updated with more SQLCAT learnings.  You can also… Read more

A Computed Column Defined with a User-Defined Function Might Impact Query Performance

Author: Kun Cheng Reviewers: Shaun Tinline-Jones, Silvano Coriani, Steve Howard, Thomas Kejser, Sanjay Mishra A computed column is computed from an expression that can use other columns in the same table. The expression can be a noncomputed column name, constant, function, and any combination of these connected by one or more operators, but the expression… Read more

Writing New Hash Functions for SQL Server

Author: Thomas Kejser Contributors/Reviewers: Alexei Khalyako, Jerome Halmans, Fabricio Voznika, Sedat Yogurtcuoglu, Mike Ruthruff, Tobias Ternstrom and Steve Howard In this blog, I will explore ideas for extending SQL Server with new, fast hash functions. As will be shown, the high speed, built in functions CHECKSUM and BINARY_CHECKSUM are not always optimal hash functions, when… Read more

Unintended Consequences of Scalar-Valued User Defined Functions

Author:            Chuck Heinzelman Reviewers:     Kevin Cox, Dan Jones, Lara Rubbelke   During a customer engagement, we noticed a query that was taking a long time to execute.  We saw that the query had a scalar-valued User Defined Function (UDF) encapsulating functionality in the SELECT clause.  To understand why this could be a problem, you need… Read more