Dimension Attributes: Introduction and Overview, Part III

Thursday May 15th 2008 by William Pearson
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Join Business Intelligence Architect Bill Pearson as he continues his subseries surrounding components of the Analysis Services dimensional model. In this article we continue our introduction to dimension attributes, focusing upon the Misc group of attribute properties.

About the Series ...

This article is a member of the series Introduction to MSSQL Server Analysis Services. The series is designed to provide hands-on application of the fundamentals of MS SQL Server Analysis Services (“Analysis Services”), with each installment progressively presenting features and techniques designed to meet specific real-world needs. For more information on the series, please see my initial article, Creating Our First Cube. For the software components, samples and tools needed to complete the hands-on portions of this article, see Usage-Based Optimization in Analysis Services 2005, another article within this series.

Introduction

In Dimensional Model Components: Dimensions Parts I and II, we introduced the dimensional model in general, noting its wide acceptance as the preferred structure for presenting quantitative and other organizational data to information consumers. We then began our examination of dimensions, the analytical perspectives upon which the dimensional model relies in meeting the primary objectives of business intelligence, including its capacity to support:

  • the presentation of relevant and accurate information representing business operations and events;
  • the rapid and accurate return of query results;
  • “slice and dice” query creation and modification;
  • an environment wherein information consumers can pose questions quickly and easily, and achieve rapid results datasets.

In Dimension Attributes: Introduction and Overview, Part II, the second of a multi-part article introducing dimension attributes, we continued our current subseries focusing upon dimensional model components, with an objective of discussing the associated concepts, and of providing hands-on exposure to the properties supporting each. We reviewed our initial introduction to the dimensional model and summarized its role in meeting the primary objectives of business intelligence. Next, we provided a brief overview of dimension attributes in general.

Having covered the general characteristics and purposes of attributes, we fixed our focus upon the properties underlying them, based upon the examination of a representative attribute within our sample cube. We discussed the Basic group of properties, looking forward to subsequent parts of our introduction and overview of dimension attributes, where we explore the remaining attribute properties groups. In this, the second part of our overview of attributes, our examination will include:

  • A continuation of our introduction to dimension attributes from a conceptual perspective;
  • Extended discussion surrounding the general characteristics of attributes;
  • An examination of the Misc group of attribute properties (including what these properties define and support, and how we can manage them).

Dimensions in Analysis Services: Attributes (continued ...)

We learned, in Dimensional Model Components: Dimensions Parts I and II, that dimensions form the foundation of the dimensional model. They represent the perspectives of a business or other operation, and reflect the intuitive ways that information consumers need to query and view data. We noted that we might consider dimensions as nouns that take part in, or are otherwise associated with, the verbs (or actions / transactions undertaken by the business) that are represented by the facts or measures contained within our business intelligence systems.

We discovered in these two articles that, within the Analysis Services model, database dimensions underlie all other dimensions, whose added properties distinguish them from the database dimensions they reference, within the model. Each dimension within our model contains one or more hierarchies. As we will learn in later articles of this subseries, two types of hierarchies exist within Analysis Services: attribute hierarchies and user (sometimes called “multi-level”) hierarchies. For purposes of most of our articles, the term “attribute” means the same thing as “attribute hierarchy”. (We will examine user hierarchies, to which we will simply refer as “hierarchies,” in subsequent articles.)

As we noted in Dimension Attributes: Introduction and Overview, Part II, we might summarize our introduction in Dimension Attributes: Introduction and Overview, Part I by stating that we might extend the metaphor we used in Part I in describing dimensions as nouns and measures as verbs, and consider attributes as somewhat similar to adjectives. That is, attributes help us to define with specificity what dimensions cannot define by themselves. Dimensions alone are like lines in geometry: they don't define “area” within multidimensional space, nor do they themselves even define the hierarchies that they contain. A database dimension is a collection of related objects called attributes, which we use to specify the coordinates required to define cube space.

As we discussed in Part I, within the table underlying a given dimension (assuming a more-or-less typical star schema database) are individual rows supporting each of the members of the associated dimension. Each row contains the set of attributes that identify, describe, and otherwise define and classify the member upon whose row they reside. For instance, a member of the Patient dimension, within the Analysis Services implementation for a healthcare provider, might contain information such as patient name, patient ID, gender, age group, race, and other attributes. Some of these attributes might relate to each other hierarchically, and, as we shall see in subsequent articles of this subseries (as well as within other of my articles), multiple conceptual hierarchies of this sort are common in real-world dimensions.

As we further discussed in Part I, Dimensions and dimension attributes should support the way that management and information consumers of a given organization describe the events and results of its business operations. Because we maintain dimension and related attribute information within the database underlying our Analysis Services implementation, we can support business intelligence for our clients and employers even when these details are not captured within the system where transaction processing takes place. Within the analysis and reporting capabilities we supply in this manner, dimensions and attributes are useful for aggregation, filtering, labeling, and other purposes.

In looking forward to our practice sessions in Part I and Part II, we stated that, in addition to a few key values, several properties (each of which has, in its own right, multiple possible values) are associated with each attribute residing in a given model. We got some hands-on exposure to some of these key values and properties in the practice session – focusing upon the Advanced properties group of attribute properties (including what they define and support, and how we can manage them). We will examine, in like manner, the Misc, Parent-Child and Source groups of attribute properties in the practice section of this (where we focus upon the Misc properties) and subsequent articles. Before we get started working within a sample cube clone, we will need to prepare the local environment for the practice session. We will take steps to accomplish this within the section that follows.

Preparation: Locate and Open the Sample Basic UDM Created Earlier

In Dimensional Model Components: Dimensions Part I, we created a sample basic UDM within which to perform the steps of the practice sessions we set out to undertake in the various articles of this subseries. Once we had ascertained that the new practice database appeared to be in place, and once we had renamed it to ANSYS065_Basic AS DB, we began our examination of dimension properties. We will continue our examination of attributes within the same practice environment, which we will access taking the following steps within the SQL Server Business Intelligence Development Studio, as we did within Dimensional Model Components: Dimensions Part II.

NOTE: Please access the UDM which we prepared in Dimensional Model Components: Dimensions Part I before proceeding with this article. If you have not completed the preparation to which I refer in the previous article, or if you cannot locate / access the Analysis Services database with which we worked there, please consider taking the preparation steps provided in Dimensional Model Components: Dimensions Part I before continuing, and prospectively saving the objects with which you work, so as to avoid the need to repeat the preparation process we have already undertaken for subsequent related articles within this subseries.

1.  Click Start.

2.  Navigate to, and click, the SQL Server Business Intelligence Development Studio, as appropriate.

We briefly see a splash page that lists the components installed on the PC, and then Visual Studio .NET 2005 opens at the Start page.

3.  Close the Start page, if desired.

4.  Select File -> Open from the main menu.

5.  Click Analysis Services Database ... from the cascading menu, as depicted in Illustration 1.


Illustration 1: Opening the Analysis Services Database ...

The Connect to Database dialog appears.

6.  Ensuring that the Connect to existing database radio button is selected, type the Analysis Server name into the Server input box atop the dialog.

7.  Using the selector just beneath, labeled Database, select ANSYS065_Basic AS DB, as shown in Illustration 2.


Illustration 2: Selecting the New Basic Analysis Services Database ...

8.  Leaving other settings on the dialog at default, click OK.

SQL Server Business Intelligence Development Studio briefly reads the database from the Analysis Server, and then we see the Solution Explorer populated with the database objects. Having overviewed dimension attributes in previous articles, we will continue to get some hands-on exposure to properties for an example attribute, from within our sample UDM.

Procedure: Examine Further Attribute Properties in Analysis Services 2005

Having continued our examination of the properties that define and support a representative attribute in Dimension Attributes: Introduction and Overview, Part II, we focused upon the Basic group of attribute properties within our practice session. In the practice procedures that follow, we will examine the properties that are classified within the Misc group of the same attribute with which we worked in Part I & Part II, namely Geography Key, one of the attributes belonging to the Geography dimension.

We will conduct our practice sessions within the SQL Server Business Intelligence Development Studio, from which we will perform our examination of attribute properties within our Analysis Services database, ANSYS065_Basic AS DB. In Dimension Attributes: Introduction and Overview, Part I, we noted that to access the properties settings for attributes within a representative dimension, we needed to open that dimension within the Dimension Designer first. (Recall that, because database dimensions, and not cube dimensions, contain attributes, we access properties supporting dimension attributes via the Dimension Designer, and not the Cube Designer.)

1.  Within the Solution Explorer, right-click the Geography dimension (expand the Dimensions folder as necessary).

2.  Click Open on the context menu that appears, as depicted in Illustration 3.


Illustration 3: Opening the Dimension via the Dimension Designer ...

The tabs of the Dimension Designer open.

3.  Click the Dimension Structure tab, if we have not already arrived there by default.

We noted in Part I that five attributes appear within the Attributes pane of the Dimension Structure tab. The attributes belonging to the Geography dimension appear as shown in Illustration 4.


Illustration 4: The Member Attributes, Geography Dimension

We will continue our examination of the properties associated with attributes by re-entering the Geography Key attribute, as before.

Overview of the Attribute Properties

As we noted in previous articles of this subseries, Analysis Services exposes many properties that determine how dimensions and dimension attributes function. We can review the properties for our selected attribute, Geography Key, within our sample UDM, by taking the following steps.

1.  Within the Attributes pane of the Dimension Structure tab, right-click the Geography Key attribute.

2.  Click Properties on the context menu that appears, as depicted in Illustration 5.


Illustration 5: Select Properties from the Context Menu ...

The Properties pane appears for the Geography Key attribute. (The Properties pane likely appeared when we selected the Geography Key attribute within the Dimensions pane, by default, below the Solution Explorer. The design environment can, of course, be customized in many ways to accommodate our local development needs.)

We can, at this stage, see the thirty DimensionAttribute properties for the Geography Key attribute within the Properties pane. We examined the first eleven properties, the members of the Advanced properties group, in Dimension Attributes: Introduction and Overview, Part I. We noted that these properties include the following:

  • AttributeHierarchyDisplayFolder
  • AttributeHierarchyEnabled
  • AttributeHierarchyOptimizedState
  • AttributeHierarchyVisible
  • DefaultMember
  • DiscretizationBucketCount
  • DiscretizationMethod
  • EstimatedCount
  • IsAggregatable
  • OrderBy
  • OrderByAttribute

The five Basic properties (which we examined in Part II), appearing underneath the Advanced properties group, include the following:

  • Description
  • ID
  • Name
  • Type
  • Usage

The Misc group comes next, (we examined them in this article), and includes the following four properties:

  • AttributeHierarchyOrdered
  • GroupingBehavior
  • InstanceSelection
  • MemberNamesUnique

Beneath the Misc group in the Properties pane lies the Parent-Child group, which includes the following five properties:

  • MembersWithData
  • MembersWithDataCaption
  • NamingTemplate
  • RootMemberIf
  • UnaryOperatorColumn

Finally, the five Source properties, appearing underneath the Parent-Child properties group, include the following:

  • CustomRollupColumn
  • CustomRollupPropertiesColumn
  • KeyColumns
  • NameColumn
  • ValueColumn

The Properties pane for the Geography Key attribute, with the Misc properties group (which we will examine in the practice session that follows) expanded, appears as shown in Illustration 6.


Illustration 6: The Properties Pane for the Geography Key Attribute (Misc Properties Expanded)

Having completed our review of the Basic attribute properties in Part II, let’s examine the next attribute properties group that appears for Geography Key.

Examine Attribute Properties: Misc Properties

Let’s take a look at the four available Misc properties for our chosen attribute example. We will again discuss the purpose of each property, examining or discussing, in most cases, possible settings with which we can come into contact within the context of the respective property.

Misc Property: AttributeHierarchyOrdered

One of several attribute properties that define and control the behavior of the attribute hierarchy, the AttributeHierarchyOrdered property setting specifies whether the members of the attribute hierarchy are ordered. The setting options are, unsurprisingly, True or False (with a default of True). While it might seem intuitive to order members most of the time, we can use this setting to conserve processing power in certain cases: if we know in advance that the associated attribute hierarchy will not be used for querying (or it is otherwise enabled, but not often used), processing time can be saved by changing this property value to False.

Misc Property: GroupingBehavior

The value we select for the GroupingBehavior property can be used to provide a “hint,” or indicator, to a client application.

1.  Click the downward arrow selector button that appears to the immediate right of the GroupingBehavior property label button, to expose the two options for selection, as depicted in Illustration 7.


Illustration 7: GroupingBehavior Property Value Selection Options

The two selection options, EncourageGrouping (the default) and DiscourageGrouping appear. As we have noted, the setting is relevant only from the perspective of a targeted client application that is designed to take advantage of the setting in the first place.

Misc Property: InstanceSelection

The value we supply to InstanceSelection is similar to that which we provide to the GroupingBehavior property, in that it can be used to provide a “hint,” or indicator, to a client application. In short, the value selected here specifies the recommended means by which a client user interface should allow selection of a member. That is, the selected setting (there are five options) provides direction to the targeted client application(s) about how they should present a list of items to users, based largely upon the expected number of items within the list involved.

2.  Click the downward arrow selector button that appears to the immediate right of the InstanceSelection property label button, to expose the five options for selection, as shown in Illustration 8.


Illustration 8: InstanceSelection Property Value Selection Options

The five selection options appear as follows:

  • None: (Default) InstanceSelection not enabled / applicable.
  • DropDown: Appropriate for situations where the number of items is small enough to display within a dropdown list.
  • List: Appropriate for situations where the number of items is too large for a dropdown list, but not large enough to require filtering.
  • Filtered List: Most useful in scenarios where the number of items is large enough to require users to filter the items to be displayed.
  • Mandatory Filter: Appropriate for situations where the number of items is so large that the display must always be filtered.

Misc Property: MemberNamesUnique

The MemberNamesUnique property setting specifies whether member names in the attribute hierarchy must be unique. The setting options are True or False (with a default of False). The setting affects how member unique names are assigned.

Having completed our review of the members of the Misc properties group, we will conclude this part of our examination of attribute properties. We will extend our introductory examination of dimension attributes, specifically continuing our discussion with the Parent-Child and Source groups of properties, within subsequent parts of this article.

NOTE: Please consider saving the project we have created to this point for use in subsequent related articles of this subseries. Doing so will allow us to avoid the need to repeat the preparation process we have undertaken, initially, to provide a practice environment.

3.  Select File -> Save All to save our work, up to this point, within the originally chosen location, where it can be easily accessed for our activities within subsequent articles of this subseries.

4.  Select File -> Exit to leave the design environment, when ready, and to close the Business Intelligence Development Studio.

Conclusion

In this, the third part of a multi-part article introducing dimension attributes, we continued our current subseries focusing upon dimensional model components, with an objective of discussing the associated concepts, and of providing hands-on exposure to the properties supporting each. We reviewed our initial introduction to the dimensional model and summarized its role in meeting the primary objectives of business intelligence. Next, we provided a brief review of dimension attributes in general.

We overviewed many of the general characteristics and purposes of attributes, including their names, and the names of the groups within which each is classified. We then continued our focus upon the properties underlying them, based upon the examination of a representative attribute within our sample cube. In this article, we extended our discussion beyond the Advanced group of properties, which we began in Part I, and the Basic group of properties, with which we continued in Part II and examined the attribute properties belonging to the Misc group, including what they define and support, and how we can manage them. We will continue our examination of attribute properties, this time for those that constitute the membership of the Parent-Child properties group, in the next part of this article.

» See All Articles by Columnist William E. Pearson, III

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