PowerPivot is great! It offers a lot of promise and it is also a great technology for Self-Service BI now! The concept of accessing data from various sources and bringing them together in a PowerPivot workbook is very powerful. And look at the amount of data that it can process. Whoever thought that Excel would ever get to this stage where it could handle more than 65,000 rows at one time? But it is still version 1.0 and as such there are a few issues when using it.
I work with SharePoint 2010 and SQL Server 2008 R2 in integrated mode. Usually I will import Reporting Services data into PowerPivot. This is a great feature. It provide out-of-the-box PowerPivot functionality. SQL Server 2008 R2 Reporting Services provides an Atom rendering extension to generate a data feed from an existing report. For best results, you should have Excel 2010 with the PowerPivot for Excel on your workstation. The PowerPivot client application will launch in response to the data feed export, automatically adding and relating the tables and columns as they are streamed in. It imports SSRS datasets, not the rendering of data. And it allows the user to select the individual report parts that the user might want to import, such as tables, lists, and/or charts.
But I have experienced a few issues with PowerPivot. I attribute them to the fact that it is version 1.0 and that improvements are probably right around the corner. Things like the refresh issue, the lack of security, etc. But here are a couple of issues that I recently experienced and I am not sure that anyone else has written about them.
To import Reporting Services data into PowerPivot I can click on the new icon that is incorporated in the Report toolbar.
Once when I was trying to import Reporting Services data into PowerPivot, the Table Import Wizard popped up as it normally does.
I clicked Next and the next window in the wizard was displayed.
Only one source table is displayed. I checked that and clicked Finish. Then the following popup appeared.
It says, "For security reasons DTD is prohibited in this XML document. To enable DTD processing set the ProhibitDtd property on XmlReaderSettings to false and pass the settings into XmlReader.Create method."
I’m thinking I have an access issue. It took a while to solve it, but I found out that my real problem was that PowerPivot was timing out. With more research I found out that what is really going on behind the scenes.
There is a new feature in SQL Server 2008 R2 Reporting Services called ATOM data feeds. The ATOM data feed allows the user to extract the data from a SQL Server 2008 R2 Reporting Services report. Each data region on the report becomes a data feed.
When I clicked on the icon to export to data feed, it re-executes the report as it generates the data for PowerPivot. And with long-running reports it could time out. That is what happened here.
How do we solve it?
SharePoint has a time limit. So one option is to increase the SharePoint time limit. The option I used, though, was to go to the report in SharePoint and under “Manage Processing Options” I set the “Data Refresh Options” to use cached data. When a report has caching enabled it only needs to be processed once within the expiry period. This means that when the first user hits that report, the report server will keep a copy until it expires, and it will serve up this copy to any users that request the report within the cache period. With the option I chose, the timeout is not an issue anymore.
I have encountered another issue.
Again I was trying to import Reporting Services data into PowerPivot. I went through the same steps described with my previous issue. I clicked the icon on the toolbar, clicked Next when the Table Import Wizard popup is displayed, checked the source table and clicked Finish when the next popup was displayed. Then the popup displays the following message.
It says, "Unable to obtain schema for data feed ’Data’. Please make sure this feed exists."
Wow! What do I do now?
Again, with more research, I find my problem. My parameter list is too long.
It can happen with any report. You can easily exceed the buffer length that SQL Server allows for a query string and cause a fatal error. My solution was use a hidden parameter to replace the multi-valued parameter list that was being passed to the report. I had a couple of instances where the user selected all of the available parameters in a multi-valued parameter list and the lists were rather long. I used the hidden parameter and when the user Selects All, instead of sending each individual parameter value, I send one value = “All” to the stored procedure. That cuts down on the size of my parameter list and allows my import of Reporting Services data into PowerPivot to work.
The next issue.
Again I was trying to import Reporting Services data into PowerPivot. I went through the regular process and the last popup looked like the following.
It says, "Input string was not in a correct format."
What?
But this time I am better prepared to solve this one. My report was using a shared dataset. I tried executing the same report without using a shared dataset and it worked. So my conclusion is that when using shared datasets I will not be able to import the Reporting Services data into PowerPivot.