Microsoft Office Tutorials and References
In Depth Information
Understanding Operational Concepts
By default, the location of the local cache is under the temporary directory of the ECS machine.
Administrators should limit the permissions to the cache directory to the ECS process account so that users
cannot go around the security of the storage locations by reading the files from the ECS cache. In addition,
you should consider using Windows Encrypted File System (EFS) to provide encryption to this folder.
The maximum workbook size has a default of 10MB. Administrators can change this workbook to
control if large files are allowed on the server. This setting can be configured for each trusted location. For
more information about settings and trusted locations granularity, see Chapter 7.
Querying Data from External Databases
You can refresh all the data connections in a workbook or drill down in an Online Analytical Processing
(OLAP) pivot table query data from an external database.
The ECS is the component that performs the data retrieval. It first determines the end-user credentials
through single sign-on (SSO), the user and password embedded in the workbook, Kerberos-constrained
delegation, or the ECS process account. The ECS then connects to the database by using those
credentials and performs the query. The ECS updates the sheet with the results of the query, and calculates
any dependent formulas before returning the result to the WFE.
Querying data from external databases is a very complex scenario in terms of the server architecture.
Chapter 5 covers external queries in depth, including the following topics:
The types of connections that are supported
The protocols and databases that can be used
The types of credentials and credential delegations that the ECS provides
Connection pooling and data caching
Asynchronous and parallel queries
Refresh on open and periodic refresh
Administrator settings for controlling and optimizing data queries
Caching and Memory Utilization
The ECS caches information in memory to improve performance. This section discusses those caches,
and the settings available to control their impact on the overall memory footprint of the ECS.
The following table outlines an example of how a workbook is cached.
User Operation
Server Operation
User opens workbook A.
Session 1 loads and calculates the workbook.
User opens workbook A in a second session.
Session 2 reuses workbook calculated by session 1.
User closes session 1 and session 2.
The workbook is kept in the cache.
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