Wednesday, May 30, 2012

Power Pivot Security Architecture Diagram

This morning (thanks to my colleague Bas) I came across a nice diagram of an end-to-end view of all the related components of PowerPivot (for Excel and for SharePoint) for SQL Server 2008 R2.


Included in this diagram are:

  • Service Accounts
  • SharePoint Databases
  • Security Hardening
  • Automatic Data Refresh
  • User Identity Flow
  • PowerPivot Permissions Levels

The original document (in Microsoft Visio, PDF, or XPS format) can be downloaded from the MS Technet site (link).


Wednesday, May 23, 2012

Microsoft TechEd Europe 2012

I'm proud to announce I am one of the already 2.5k+ attendees at the TechEd Europe in Amsterdam next month!
I allready put up my agenda at europe.msteched.com, to attend at least some of the sessions of the following speakers:

See you all at the TechEd!


Monday, May 21, 2012

Performance difference between DISTINCT and GROUP BY


I was wondering if the following two queries differ in performance when used in SQL Server.
select DISTINCT persNrDV, volgnrDienstverband from medewerker
select persNrDV, volgnrDienstverband from medewerker 
GROUP BY persNrDV, volgnrDienstverband

The goal of both of the above queries is to produce a list of distinct employee numbers and employment numbers from the employee table. The first query uses SELECT DISTINCT to accomplish this task, and the second query uses GROUP BY.
I ran these queries with the Execution Plan option turned on, I found that not only the results are identical, but the Execution Plans are also identical. The SQL Server Query Optimizer has the ability to decipher each query, determining what the ultimate results are, and to produce the most efficient Execution Plan possible.
So my conclusion is that there is no performance advantage using one form of the query over the other.

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