Craig Freedman's SQL Server Blog

A discussion of query processing, query execution, and query plans in SQL Server.

July, 2007

Blog - About

About Craig Freedman's WebLog

About my blog

I am using this blog to write about how query processing works in SQL Server.

Some of the topics that I write about:

  • How to read and understand query plans and query operators.
  • How different query plans affect performance.
  • The tradeoffs made by the query optimizer when choosing query plans.
  • How subtle changes to a query can affect the choice of plan and impact performance.

About me

I've been developing commercial database engines and working on query processing for more than 10 years.  I've worked for the SQL Server team for more than 5 years and am a co-author of Inside Microsoft SQL Server 2005: TM 2005: Query Tuning and Optimization" href="http://www.microsoft.com/MSPress/books/8565.aspx" mce_href="http://www.microsoft.com/MSPress/books/8565.aspx">Query Tuning and Optimization.  You can learn more about me at this SQLServerCentral.com interview.

  • Craig Freedman's SQL Server Blog

    ROWCOUNT Top

    • 8 Comments
    If you've looked at any insert, update, or delete plans, including those used in some of my posts, you've probably noticed that nearly all such plans include a top operator. For example, the following update statement yields the following plan: CREATE...
  • Craig Freedman's SQL Server Blog

    The UNPIVOT Operator

    • 3 Comments
    The UNPIVOT operator is the opposite of the PIVOT operator. As I explained in my earlier post , the PIVOT operator takes a normalized table and transforms it into a new table where the columns of the new table are derived from the values in the original...
  • Craig Freedman's SQL Server Blog

    PIVOT Query Plans

    • 0 Comments
    In my last post , I gave an overview of the PIVOT operator. In this post, I'm going to take a look at the query plans generated by the PIVOT operator. As we'll see, SQL Server generates a surprisingly simple query plan that is essentially just a fancy...
  • Craig Freedman's SQL Server Blog

    The PIVOT Operator

    • 10 Comments
    In my next few posts, I'm going to look at how SQL Server implements the PIVOT and UNPIVOT operators. Let's begin with the PIVOT operator. The PIVOT operator takes a normalized table and transforms it into a new table where the columns of the new table...
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