The Data Modeling Workspace › Logical and Physical Modeling › Comparison of Logical and Physical Model Objects

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Comparison of Logical and Physical Model Objects

Most of the objects in the logical model correspond to a related object in the physical model. For example, the logical model contains entities, attributes, and key groups, which are represented in the physical model as tables, columns, and indexes, respectively. In the following table, see how logical and physical components compare in a typical model:

Logical Model

Physical Model

Entity

Dependent entity
Independent entity

Table

FK is part of child table's PK
Parent table or, if child table,
FK is NOT part of child table's PK

Attribute

Logical datatype (text, number, datetime, blob)

Column

Physical datatype such as char(18), int, or varchar

Domain (logical)

Domain (physical)

Key Group

Primary key (PK)
Foreign key (FK)
Alternate key (AK)
Inversion entry (IE)

Index

PK (in model) and PK Index (in schema)
FK (in model) and FK Index (in schema)
A unique, non-primary index
A non-unique index

Relationship

Identifying
Non-Identifying
Subtype
Many-to-many
Referential Integrity
Cardinality

Relationship implemented using FKs

FK is part of child table's PK (above the line)
FK is NOT part of child table's PK (below the line)
Denormalized tables
Associative table
INSERT, UPDATE, and DELETE Triggers
Zero, One or More, One or More; Zero or One; Exactly

Not applicable

View or View Relationship

Not applicable

Pre- and Post-script

Note: You can specify whether an object is included in the logical model only, the physical model only, or both, by using the Logical Only and Physical Only check boxes in the corresponding property editor.

More information:

Logical and Physical Model Denormalization

How to Resolve Many-to-Many Relationships

Switch Between Logical and Physical Models