KNOWLEDGE BASE

Blending with Multiple Secondary Data Sources Returns Incorrect Values


Published: 28 Jul 2017
Last Modified Date: 31 Jul 2017

Issue

When one secondary data source is blended on a higher level of granularity than the view, and another secondary data source is not blended on this field, the other secondary data source might return duplicate values.

Environment

  • Tableau Desktop 

Resolution

Try one of the following options, as appropriate for your workbook: 
  • It may be possible to cross database join instead of blending. See Join Your Data for more information.
  • Filter each of the data sources independently on the more granular dimensions.
  • Make sure that you are blending on dimensions present in the view or on all of the same dimensions across secondary data sources.

Cause

A primary data source is partitioned behind the scenes by the fields that it has been linked on. So if a dimension not present in a view is blended on one secondary data source but not a second secondary data source, the view is partitioned and the blend duplicates values for the second secondary data source.
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