Priority Groups is being used to prioritized the LTS to BI server while creating the SQL query.
For example, lets consider a case where there are 2 aliases for the same dimension CHANNELS as shown below
In the business model and mapping layer, lets assume that both the LTS are mapped to all the columns. Both the LTS are at the same detail level. Now, lets assign a priority group of 0 for the Channel Alias – B LTS and a priority group of 1 for the Channel Alias – A LTS. Also the SALES LTS of the Fact table will also be assigned to the priority group 0. In 11g, the LTS with the least number is considered as the one that has to be chosen for querying (highest priority)
Now, lets create a report containing columns from Channels dimension and the Sales fact.
If you look at the query of the report, you will notice that Channels Alias – B will be chosen as it is the one having the highest priority.
Lets now go back to the repository and reassign the highest the priority to Channels Alias – A as shown below
For the same report, if you look at the query now, you will notice that Channels Alias – A will be chosen instead of the B alias.
