See series starting at
The First Normal Form in Theory and Practice Part I
I'm not sure why you think integrity constraints are purely logical. Primary keys are physical constraints. They enforce that the primary key remains unique. Here's an example of SQL that creates a physical foreign key constraint.
ALTER TABLE FactInventoryCollections
ADD CONSTRAINT
FK_FactInventoryCollections_ClientPK,
FOREIGN KEY (ClientPK)
REFERENCES ViewCubeDimClient(ClientPK);
Physical constraints allow the database engine to return an error if an operation attempts to insert a row that violates any defined constraints. --LinkedIn.com
When One Data Model Just Won't Do: Polyglot Persistence
I have been in the data side of IT for quite some time now and have seen the evolution of how data is ingested, manipulated and regurgitated to the end users in hope of telling our consumers "how much of something did something". The main issue seems to be complexity of the data models and the fact we don't have a model that can expand with the data without adding tons of new schema. The solution. --LinkedIn.com