ER/Studio - Embarcadero Technologies Product Documentation

USING ER/STUDIO > DEVELOPING THE PHYSICAL MODEL
The physical design focuses on performance and tuning issues for a particular database platform. A highly normalized
database design often results in performance problems, particularly with large data volumes and many concurrent
users. These problems are often due to complex query patterns, the cost of multi-table joins, and the high I/O intensity
of querying or modifying large tables. When addressing performance problems, you should consider the following
physical design issues:
• Transforming Model Objects from Logical to Physical: How the elements of a physical model correspond to the
elements of the corresponding logical model.
• Optimizing Query Performance on the Physical Model: How to modify the logical design to increase the efficiency
of database operations.
• Creating and Editing Indexes: How to create indexes to increase the efficiency of read operations (queries)
without sacrificing the efficiency of write operations (insert, update, delete).
• Physical Storage Considerations: How to determine the physical storage of the tables and indexes in the
database to maximize efficiency and allow for growth.
For information on physical data model objects in ER/Studio, see the following topics:
• Creating and Editing Entities and Tables
• Creating and Editing Attributes and Columns
• Customizing Table DDL
• Creating and Editing Indexes
• Defining Table Storage
• Creating and Editing Database Dependent Objects
Creating and Editing Tables
For information on creating and editing tables, see
• Creating and Editing Entities and Tables
• Creating and Editing Attributes and Columns
Transforming Model Objects from Logical to Physical
Before considering physical design issues, it is important to understand how a physical design maps to its
corresponding logical design. When ER/Studio derives a physical design from a logical one, it transforms logical
model objects into their physical model analogs. The table below details how different logical objects are transformed
into physical objects. Understanding the transformation lets you better assess the impact of altering the physical
design to differ from the logical design.
The table below describes logical model objects and their corresponding physical model objects:
Logical
Model Object
Physical Model
Object
Notes
Entity Table An entity translates directly into a table. In a dimensional model, tables are
automatically assigned types (fact, dimension, snowflake, or undefined) based on an
analysis of the schema.
Attribute Column An attribute translates directly into a table column.
EMBARCADERO TECHNOLOGIES > ER/STUDIO® 8.0.3 USER GUIDE 144