Specifications

PowerPivot for SharePoint CHAPTER 10 203
balancing across servers for query processing if multiple servers are available. Furthermore,
the PowerPivot System Service manages the connections for active, reusable, and cached
connections to PowerPivot workbooks, as well as administrative connections to other Power-
Pivot System Services on the SharePoint farm.
To speed up access to data, the PowerPivot System Service caches a local copy of a work-
book and stores it in Program Files\Microsoft SQL Server\MSAS10_50.POWERPIVOT\OLAP\
Backup. The service unloads this copy of the workbook from memory if no one has accessed
the workbook after 48 hours and deletes it from the folder after an additional 72 hours of
inactivity. If a user updates the workbook in SharePoint and a copy of the workbook already
exists in the cache, the PowerPivot System Service also removes the older cache copy.
The PowerPivot Database
Each service application has its own relational database, called the PowerPivot database. In
particular, this PowerPivot database stores the load or cache status of workbooks, server usage
information, and schedule information for data refresh operations. More specically, the
application database stores an instance map that identies whether a workbook is currently
loaded on the server or in the cache. Usage information in the application database applies to
connections, query response times, load and unload events, and other information pertinent to
server health statistics. The data refresh schedule information includes details about data sources,
users, and the workbooks associated with a schedule. None of the workbook content is in the
PowerPivot database. Instead, workbooks are stored in the SharePoint content database.
The PowerPivot Web Service
The PowerPivot Web Service is a thin middle-tier connection manager implemented as a Win-
dows Communication Foundation (WCF) Web service that runs on a SharePoint Web front end.
The Web service listens on the port assigned to a Web application enabled for PowerPivot, and
responds to requests by coordinating the request-response exchange between client ap-
plications and PowerPivot for SharePoint instances in the farm. This Web service requires no
separate conguration or management.
The PowerPivot Managed Extension
The PowerPivot Managed Extension is an assembly in the Analysis Services OLE DB provider
client. This provider client is installed on a client computer when you install the PowerPivot
for Excel add-in, and on the SharePoint server when you install PowerPivot for SharePoint. For
managed connections, the Web service and the managed extension operate the same way.
The query processing request determines which one is used.