Defining Analysis Services Dimensions - SQL Server Analysis Services 2012 Cube Development - page 22

each type of data source. If you check the Cartridges folder under your Analys-
is Services installation directory (by default, this folder will be under c:\Program
Files\Microsoft SQL Server\instance name\OLAP\bin\ ), you will find
XSL files for each supported data source. These cartridge files control how SSAS
interacts with various relational databases.
There's more...
Now that you have created the data source, you can review and edit its properties
by right-clicking on it in the Solution Explorer window within SSDT and selecting
Open . This screen reveals a few additional properties, which can be useful for fine
tuning your data source configuration; they are given in the following bullet list:
• Isolation : This property configures the transaction isolation level for retriev-
ing data from relational tables. The default (and recommended) value is
Read Committed . You also have an option of using the snapshot isolation
level. The discussion of transaction isolation levels is beyond the scope of
this topic. However, you should be aware that different isolation levels use
different types of locking strategies to ensure data consistency.
• Query timeout : This property allows you to specify the number of seconds
during which SSAS should run the SQL statement used for processing any
object within this data source, after which the relational query should timeout.
If you have a busy relational database used to populate SSAS objects, the
stability of the relational source might be more important than having up-
to-date data in Analysis Services. Therefore, you might want to throttle the
amount of time a processing query takes to run. The default value is 0 , which
means that queries aren't limited at the data source level. Analysis Ser-
vices has a configuration property that controls how long processing queries
should run before the timeout; please refer to Chapter 8 , Administering and
Monitoring Analysis Services , for more information.
• The maximum number of connections property defaults to 10, and controls
how many connections SSAS can establish with the data source while pro-
cessing its corresponding objects.