Chapter 11
WarehouseArchitect Model Basics

About this chapterThis chapter presents the WarehouseArchitect Model (WAM).

What is a WAM?

The WAM specifies the physical implementation of the data warehouse.

With the WAM, you consider the details of actual physical implementation. It takes into account both software or data storage structures. You can modify the WAM to suit your performance or physical constraints.

WAM rolesYou can use or create a WAM to:

Represent the physical organization of data in a graphic format

Reverse engineer existing databases

Import objects with traceability links

Define referential integrity triggers and constraints

Generate data warehouse creation and modification scripts

Generate extraction scripts

Generate files for OLAP or decision support systems

WAM creationThere are several ways to create a WAM:

Import one or more existing PDM

Import one or more existing WAM

Reverse-engineer an existing database creation script

Reverse-engineer an existing database via an ODBC connection

Create a WAM from scratch

Objects in a WAM

A WAM represents the interaction of the following objects:

Object

Description

Table

Collection of rows (records) that have associated columns (fields)

Column

Data structure that contains an individual data item within a row (record), model equivalent of a database field

Primary key

Column or columns whose values uniquely identify a row in a table

Alternate key

Column or columns whose values uniquely identify a row in a table and are not primary key columns

Foreign key

Column or columns whose values depend on and migrate from a primary key, or alternate key, in another table.

Index

Data structure that is based on a key and that speeds access to data and controls unique values

Reference

Link between the primary key, or an alternate key, and a foreign key of different tables. Depending on its selected properties, a reference can also link columns that are independent of primary and alternate key columns

View

Data structure that results from a SQL query and that is built from data in one or more tables

Fact

Focus of a decision support investigation. Is connected to a fact table

Dimension

Axis of investigation of a fact. Is connected to a dimension table

Fact hierarchy

A fact that is split into other facts. Results from aggregation or partitioning of a fact table

Dimension hierarchy

A dimension that is split into other dimensions. Each descending level in a dimension hierarchy corresponds to a finer level of detail

Attribute

Object that qualifies a dimension. Is connected to a column in a dimension table

Metric

Variable or measure that corresponds to the focus of the decision support investigation. Is connected to a column in a fact table

Object	Description
Table	Collection of rows (records) that have associated columns (fields)
Column	Data structure that contains an individual data item within a row (record), model equivalent of a database field
Primary key	Column or columns whose values uniquely identify a row in a table
Alternate key	Column or columns whose values uniquely identify a row in a table and are not primary key columns
Foreign key	Column or columns whose values depend on and migrate from a primary key, or alternate key, in another table.
Index	Data structure that is based on a key and that speeds access to data and controls unique values
Reference	Link between the primary key, or an alternate key, and a foreign key of different tables. Depending on its selected properties, a reference can also link columns that are independent of primary and alternate key columns
View	Data structure that results from a SQL query and that is built from data in one or more tables
Fact	Focus of a decision support investigation. Is connected to a fact table
Dimension	Axis of investigation of a fact. Is connected to a dimension table
Fact hierarchy	A fact that is split into other facts. Results from aggregation or partitioning of a fact table
Dimension hierarchy	A dimension that is split into other dimensions. Each descending level in a dimension hierarchy corresponds to a finer level of detail
Attribute	Object that qualifies a dimension. Is connected to a column in a dimension table
Metric	Variable or measure that corresponds to the focus of the decision support investigation. Is connected to a column in a fact table

Defining a WAM

You define a WAM from the model property sheet.

Defining WAM options

You can set the following WAM options:

Option

Description

Enforce

When selected, does not allow columns to diverge from domains for certain uses (see table below)

Default data type

Data type to apply to columns and domains if no data type is selected

Unique code

When selected, requires that references have unique codes

Auto-migrate FK

When selected, migrates foreign keys automatically with their corresponding domain, check parameters, and validation rules. You can choose to automatically migrate extended attributes

Confirm

When selected, offers choice between deleting symbols only or deleting symbols and their associated objects in the dictionary

You can enforce domains for the following uses:

Option	Description
Enforce	When selected, does not allow columns to diverge from domains for certain uses (see table below)
Default data type	Data type to apply to columns and domains if no data type is selected
Unique code	When selected, requires that references have unique codes
Auto-migrate FK	When selected, migrates foreign keys automatically with their corresponding domain, check parameters, and validation rules. You can choose to automatically migrate extended attributes
Confirm	When selected, offers choice between deleting symbols only or deleting symbols and their associated objects in the dictionary

Use

Columns in the domain cannot have divergent

Data type

Data type, length, and precision

Check

Check parameters

Rules

Business rules

Mandatory

Mandatory or optional property

Extended

Extended attributes

If you modify WAM options, these options apply to the current WAM and every WAM you create subsequently.

Use	Columns in the domain cannot have divergent
Data type	Data type, length, and precision
Check	Check parameters
Rules	Business rules
Mandatory	Mandatory or optional property
Extended	Extended attributes

For information on other model options, see Chapter 2 Managing Models.

To define WAM options:
1. Select File→Model options.
  The Model Options dialog box opens to the General page.
2. Select WAM options.
3. Click OK.

WAM properties

The WAM definition includes the following properties:

Property

Description

Maximum length

In title box?

Project name

Name for the project. This name identifies WAM and submodels that work together in a project

80

(

Project code

Reference name for the project

80

--

Database name

Name of the target database for the model

--

--

Name

Name for the model. This name makes the model identifiable

80

(

Code

Reference name for the model. On the physical level, this code is generated in database scripts

80

--

Label

Descriptive label for the model

254

--

Author

Name or initials of the author of the model

80

(

Version

Specifies the version of the model

8

(

Language

Language of the model. For a limited number of languages, this property also indicates the language of the title box and of default report templates

--

(

Created

Date and time of model creation

--

--

Modified

Date and time of last model modification

--

(

File

Full pathname of the WAM file

--

--

Property	Description	Maximum length	In title box?
Project name	Name for the project. This name identifies WAM and submodels that work together in a project	80	(
Project code	Reference name for the project	80	--
Database name	Name of the target database for the model	--	--
Name	Name for the model. This name makes the model identifiable	80	(
Code	Reference name for the model. On the physical level, this code is generated in database scripts	80	--
Label	Descriptive label for the model	254	--
Author	Name or initials of the author of the model	80	(
Version	Specifies the version of the model	8	(
Language	Language of the model. For a limited number of languages, this property also indicates the language of the title box and of default report templates	--	(
Created	Date and time of model creation	--	--
Modified	Date and time of last model modification	--	(
File	Full pathname of the WAM file	--	--

Modifying model properties

The Model property sheet displays the definition of the current model. From this property sheet you can modify the model definition.

To modify the model properties:
1. Select Dictionary→Model Properties.
  or
  If you have inserted a title box, click the Property tool and then the title box.
  The model property sheet appears.
2. Type changes to model properties.
3. Click OK.

Opening an existing PDM

A WAM is a PDM that contains or can contain certain additional objects and attributes corresponding to objects and attributes in a Data Warehouse database. You can build a WAM from an existing PDM.

To open an existing PDM:
1. Select File→Open.
  A standard Windows File Open dialog box appears.
2. Select PDM Model (*.pdm) from the Files of Type dropdown listbox.
  or
  Select All (*.*) from the Files of Type dropdown listbox.
3. Select a file with a PDM extension, and click OK.
  The PDM appears in the WarehouseArchitect workspace.
4. (Optional) Change the target database, if necessary.
5. Select File→Save As.
  A standard Windows File Save As dialog box appears. The Files of Type default is WAM Model (*.wam).
6. (Optional) Change the filename of your model.
7. Remove the PDM extension from the filename in the File Name box.
8. Click OK.


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WarehouseArchitect - User's Guide

Chapter 11 WarehouseArchitect Model Basics