Logical to Physical with Polyglot Relationships

Polyglot relationships are defined at a conceptual and logical level, independently of any physical technology.  When you derive a physical model from a Polyglot model, each relationship is translated into a construct supported by that target.

 

During derivation, relationships are translated in the most appropriate way for each target, based on:

• what the target supports,
• and what you expressed in the Polyglot model.

 

Targets with Foreign Key / Foreign Master

This includes relational databases, NoSQL databases with the exclusion of graph database (see below), and all targets that support relationships, even if not enforced:

• relationships already defined as Foreign Key / Foreign Master are derived as-is.
• many-to-many relationships without relationship attributes may result in an associative table for relational targets (configurable, enabled by default).
• relationships that carry attributes are automatically materialized as an associative table. The associative structure contains the relationship attributes and two Foreign Key relationships toward the originally linked entities.  Such transformation is mandatory for these targets: since Foreign Key-based platforms do not support attributes directly on relationships, generating an associative entity (a.k.a junctions tables, join tables, bridge tables, link tables, intersection tables, mapping tables, crosswalk, or many-to-many resolver) is the only way to preserve the relationship attributes without information loss.

 

Targets with Edges (graph databases)

For graph-only targets, all relationships become edges.

• all Polyglot relationships are derived as edges, regardless of how they were modeled.
• linked entities become source and target nodes.
• direction follows the graph convention (out-node → in-node), using the order of linked entities.

 

Polyglot to Polyglot

When deriving a Polyglot model into another Polyglot model, relationships carrying attributes are, by default, materialized as associative entities.

This reflects the typical modeling progression from a conceptual structure toward a more explicit logical model.  A relationship that carries attributes (for example, Order-Product with quantity) becomes an associative entity with two Foreign Key relationships to the originally linked entities.

An option during the derive operation allows you to disable this behavior.  If the option is unchecked, relationships carrying attributes remain unchanged and are preserved as relationships with attributes in the derived Polyglot model.  The option is enabled by default.

 

Not derived information

Some relationship properties are conceptual or logical only and are not propagated to physical models, regardless of the target:

• verbs,
• roles,
• constraint type (identifying vs non-identifying).

 

These properties enrich understanding in Polyglot but do not currently map to physical constructs.