Physical Layer Joins & Connection Pools
Understand how physical table joins, keys, and connection pools are configured to enable correct and efficient query generation.
The Physical layer is where the RPD grounds itself in reality — every join here must reflect an actual, valid relationship in the source database, because the BI Server trusts these joins completely when generating physical SQL. Getting a physical join wrong doesn't just produce a wrong report; it can silently multiply rows (fan-out) or drop rows (unintended inner join) with no obvious error.
Physical joins are like the actual plumbing between rooms in a house — you can't just declare two rooms connected on a floor plan (BMM) if there's no real pipe between them. Connection pools are like separate water lines for the kitchen versus the sprinkler system, so watering the lawn doesn't cut off the kitchen's water pressure.