Tuesday, March 3, 2009

T-SQL: A Set-Oriented Language + Ranking Functions

The other day I had a query that invloved several tables and complex logic to a certain degree. The initial query involved using user-defined functions and the such and it took roughly 12 minutes to run which was not acceptable. After a little bit of tweeking and thinking of sets and not procedural logic I managed to the query to run in under 10 seconds for the same amount of data. Thanks partially to t-sql ranking functions [ http://msdn.microsoft.com/en-us/library/ms189798.aspx#]

Dense_Rank was especially useful. Unlike Rank(), Dense_Rank() does not leaves gap in the sequence of numbers desginating ranks.

No comments:

Post a Comment