Microsoft Office Tutorials and References
In Depth Information
Understanding Operational Concepts
User Operation
Server Operation
User opens workbook A in a third session.
Session 3 reuses calculated workbook from
User closes session 3.
The workbook is returned to the cache.
No activity.
The server frees resources, and the workbook is
User opens workbook A in a fourth session.
Session 4 loads and calculates the workbook.
Workbooks are kept in the cache so they do not have to be reloaded and recalculated for every new session.
Sharing Workbooks Between Sessions
There are some cases in which it is not possible to share a workbook. For example, to avoid disclosing
personal information, if the workbook refreshes a data query that uses the end-user’s credentials on
open, the query results are not shared.
The following list shows some of the cases in which it is not possible to share a workbook state between
sessions and require recalculation for each session:
The user has performed some interactivity on the workbook (for example, the user has set some
parameters values or has drilled down in a pivot table). In that case, the workbook state is private
to the session and will not be shared.
The workbook contains the results of a data query that was performed with different credentials.
(For more details on external queries and their caching implications, see Chapter 5.)
The workbook contains calls to user-defined functions (UDFs) that are marked as returning
personal information.
The workbook contains some volatile functions (for example =Now() or =Rand()) and the Volatile
Function Cache Lifetime administrator setting does not allow for sharing the workbook state. This
setting allows administrators to specify the maximum amount of time in which workbooks that
contain volatile functions can be reused from the cache, in order to trade the accuracy of these
volatile functions with performance and better caching. The default value is 5 minutes. This
setting can be configured for each trusted location. (For more information about settings and trusted
locations granularity, see Chapter 7.)
Managing Unused Objects
A workbook can be used by one or more sessions, or not used by any session. If the workbook is unused,
then it may be kept in the cache as long as resources are available.
The ECS will free some of the unused objects if one of the following conditions is met:
A memory allocation has failed.
One of the administrator settings for the management of unused objects is exceeded.
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