By enabling Allow Duplicates, you ensure that OLAP Exchange® will allow Cube-building to proceed when it detects two identical Member values in a table. Typically, this would occur when you are building a Dimension other than Measures from your Measures table.
Important
On the other hand, keep in mind that tables such as Product Master or Customer
Master used as the basis for building Dimensions should contain
unique names—e.g.,
there should not be two different products with the same name in a Product
Master table. If this occurs, you can concatenate the Product Code with
Product Name to differentiate the two. Otherwise, if Allow Duplicates
is used, this will create a single product for which data for both products
would be aggregated.
Let's consider an example of when you might want to use Allow Duplicates. In the Measures table you might find a field that records the time when transactions occur—suppose month is the only thing specified. It is very likely that more than one transaction will occur per month; thus, if you are building a Months dimension from this table you must account for the fact that January, for example, will be "duplicated" in the field. By clicking on the Allow Duplicate Members check box, you ensure that you can proceed with the creation of a Months dimension, where each month will be listed as a Member.
If you do not check Allow Duplicates in this case, you will not be allowed to proceed with Cube creation.
To give a solid example for this particular feature only, you can try to create a new cube called Test Duplicates. Assuming you will create your Measures dimension from the dbo.Orders Details SQL table like in the previous exercise. Additionally, you want to create a dimension called ShipCountry from the dbo.Orders dimension. By creating a preview of the dbo.Orders table, you will see that some countries (e.g., France) appear more than once in the table.
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When you proceed to create the dimension following the same process, where you first create a link to your dbo.Order Details table and dbo.Orders table (Star Schema) then designate the member by selecting a field/s (ShipCountry field). If Allow Duplicates feature is not enabled, when you finish creating the ShipCountry dimension, you will receive a message like the one following (Where the Table value France appears more than once).
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To enable duplicates to be processed:
1. Return to the Define Members screen.
2. Check Allow Duplicates check box option.
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For the next topics go back to using the Order Information Cube and corresponding Dimensions.
Important
Some features of OLAP Exchange®, including the Allow Duplicates
option (provided it is not enabled) will clue you in to issues
and anomalies in your underlying database.
Refer to Section on Administrator Topics, Prepare
Relational Data for Use With OLAP Exchange and Error
File Reporting.