Proactive Caching Settings
As we have noted in other
articles within this series, when we use MOLAP or HOLAP storage, the data in the affected cube
becomes stale the second the relational data source changes. Proactive
Caching is a feature in Analysis Services that allows us to specify when to
process a measure group partition or a dimension as the data in the relational
data source changes. When Proactive Caching is implemented, Analysis
Services handles maintaining updates on its own, based upon parameters we
specify. A common scenario for Proactive Caching would include a
situation where we have a measure group partition where the latest data is
added periodically, and then at some point the partition is merged with an
existing partition. The data for our partition is often determined based upon
a transaction date. For instance, we might want the partition updated
hourly during the day with new transactions, and then at night we might merge
the contents of the partition into a partition for the current week. This
approach would enable us to process the partition often, keeping it synchronized
often with the relational data source, while also minimizing the amount of data
that needs to be processed each cycle.
Because Proactive Caching
is established at the partition level, the need to provide this update
capability is a partition planning criterion. We might, for example, choose to
provide a partition for the data of the current year, wherein we might
implement Proactive Caching, while we might create a partition, sans Proactive
Caching, for historical data.
We can access Proactive
Caching settings within the Business Intelligence Development Studio through any
of the following means:
-
Clicking
the ellipsis button (...) for the ProactiveCaching property value of a dimension,
cube, measure group, or partition in the respective Properties window of Business
Intelligence Development Studio;
-
Expanding
a measure group in the Partitions tab of Cube Designer and clicking Storage
Settings;
-
Expanding
a measure group and selecting a partition in the grid for that measure group in
the Partitions tab of Cube Designer and clicking Storage Settings;
-
Expanding
a measure group and selecting a partition in the grid for that measure group in
the Partitions tab of Cube Designer and clicking Storage settings on the Toolbar
of the Partitions tab of Cube Designer.
1.
Ensure that
the Internet_Sales_2003 partition of the Internet Sales measure group is
selected, once again, on the Partitions tab.
2.
Select Cube -> Storage Settings ... from the menu atop the Partitions
tab, as depicted in Illustration 35.
Illustration 35: Select Cube -> Storage Settings ... from the Menu atop the Partitions Tab
We return to the Partition
Storage Settings – Internet_Sales_2003 dialog that
we encountered in an earlier section above. As we mentioned there, we can use Settings here to
specify the proactive caching, storage, and notification settings for a dimension,
cube, measure group, or partition. We can set storage type through the use of
the setting slider that we see by clicking the radio button labeled Standard
setting, and enabling the slider with its predefined settings for storage mode
and proactive caching features. The predefined settings, along with
descriptions, appear in Table 1 above.
3.
Click Cancel to
dismiss the dialog.
4.
Exit Business
Intelligence Development Studio, when desired.
Conclusion
In this
article, we continued the general exploration of cube storage that we began in Cube Storage: Introduction, this time
focusing upon partitions, which we initially introduced in Cube Storage: Introduction to Partitions. We
noted that this article was one of several others in this subseries that
explore various concepts surrounding partitions in Analysis Services. We
discussed partition planning considerations and how they are important to partition
design within our business intelligence solutions.
After
discussing partition planning in general in Analysis Services, we explored each
of several individual resource assignment and settings considerations in
planning partition design within Analysis Services. Finally, for each of the resource
assignment and settings considerations we discussed, we examined a respective example
resource assignment / setting within the Adventure Works sample cube, from the
perspective of the Cube Designer of the Business Intelligence Development
Studio, where applicable.
About the Series ...
This
article is a member of the series Introduction
to MSSQL Server Analysis Services. The monthly column is designed to provide hands-on
application of the fundamentals of MS SQL Server Analysis Services (“Analysis
Services”), with each installment progressively presenting features and
techniques designed to meet specific real-world needs. For more information on
the series, please see my initial article, Creating Our First Cube.
»
See All Articles by Columnist William E. Pearson, III
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