Setting Priority Group Numbers for Logical Table Sources

You can set priority group numbers to determine which logical table source should be used for queries for which there is more than one logical table source that can satisfy the requested set of columns.

For Example , A column is mapped to multiple LTS(LTS1 & LTS2)  and you want to give first priority to LTS1 whenever this particular column is being fetched in the report so in this case you can assign a higher priority to LTS1.

To assign priority group numbers, rank your logical table sources in numeric order, with 0 being the highest-priority source and so on.
Assigning priority groups is optional. All logical table sources are set to priority 0 by default.

See below snapshot: