Microsoft KB Archive/936595

= FIX: The estimate of the number of children that a dimension member has may be inaccurate when you request the CHILDREN_CARDINALITY property for a dimension member in SQL Server 2005 Analysis Services =

Article ID: 936595

Article Last Modified on 11/4/2007

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APPLIES TO


 * Microsoft SQL Server 2005 Analysis Services

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Bug #: 50001104 (SQL Hotfix)



Microsoft distributes Microsoft SQL Server 2005 fixes as one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release.



SUMMARY
This article describes the following about this hotfix release:
 * The issues that are fixed by the hotfix package
 * The prerequisites for installing the hotfix package
 * Whether you must restart the computer after you install the hotfix package
 * Whether the hotfix package is replaced by any other hotfix package
 * Whether you must make any registry changes
 * The files that are contained in the hotfix package



SYMPTOMS
In Microsoft SQL Server 2005 Analysis Services, you request the CHILDREN_CARDINALITY property for a dimension member. When you do this, the estimate of the number of children that a dimension member has may be inaccurate. A dimension member may indicate that it has children when it does not have children. Additionally, the estimate may be less precise than the estimate that is returned for the same dimension member in Microsoft SQL Server 2000 Analysis Services.



CAUSE
This problem occurs because the CHILDREN_CARDINALITY property for a dimension member is defined as an estimated value in the Microsoft OLE DB for OLAP specification.

In SQL Server 2000 Analysis Services, a dimension is defined by the levels of the hierarchy. In SQL Server 2000 Analysis Services, multiple-hierarchy dimensions are multiple dimensions from the perspective of the server. This architecture of hierarchy-based dimensions allows for very accurate estimates. The estimates are very accurate because the dimension structures are materialized on the server when the server starts. Additionally, the dimension structures are loaded into the memory on the server when the server starts.

In SQL Server 2005 Analysis Services, dimensions and hierarchies do not have a one-to-one relationship. A dimension is a collection of related attributes. A hierarchy is only a navigational construct that consists of one attribute from the dimension or that consists of more than one attribute from the dimension. An attribute can have multiple values for the CHILDREN_CARDINALITY property. This behavior occurs if the attribute participates in multiple hierarchies that have different attributes as children in the various hierarchies. Additionally, SQL Server 2005 Analysis Services does not require all the dimension members to be loaded into memory. Therefore, it is much more costly to accurately determine the children for a specific dimension member. To avoid the potential performance effects of retrieving the actual number of children for a dimension member and of counting the actual number of children for a dimension member, SQL Server 2005 Analysis Services returns 0 for dimension members that do not have children. Additionally, SQL Server 2005 Analysis Services returns 1,000 for dimension members that have children. However, SQL Server 2005 Analysis Services may be unable to efficiently determine whether a dimension member has children in some cases.



Cumulative update information
To resolve this problem, obtain the cumulative update package (build 3175) for SQL Server 2005 Service Pack 2 (SP2). For more information, click the following article number to view the article in the Microsoft Knowledge Base:

936305 Cumulative update package 2 for SQL Server 2005 Service Pack 2 is available

Hotfix information
A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites
 SQL Server 2005 Service Pack 1 (SP1)

For more information about how to obtain SQL Server 2005 Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:

913089 How to obtain the latest service pack for SQL Server 2005



Restart information
You do not have to restart the computer after you apply this hotfix. However, this hotfix stops the Analysis Services service, and then this hotfix restarts the Analysis Services service. If you configured Analysis Services for HTTP access, you must stop Internet Information Services (IIS), and then you must restart IIS after the installation is complete. If you installed Analysis Services as a named instance, you must stop the SQL Server Browser service because the Msmdredir.dll component of the SQL Server Browser service is updated when you apply this hotfix.

Registry information
You do not have to change the registry.

Hotfix file information
This hotfix contains only those files that are required to correct the issues that this article lists. This hotfix may not contain all the files that you must have to fully update a product to the latest build.

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

SQL Server 2005 Itanium architecture version


STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
After you apply this hotfix, SQL Server 2005 Analysis Services returns an accurate estimate for parent/child hierarchies and for natural hierarchies. Additionally, to avoid significant performance effects when SQL Server 2005 Analysis Services counts the actual number of children, the estimate is incorrect when one of the following conditions is true:
 * You implement the dimension security feature.
 * You set the HideMemberIf property of a level that makes the hierarchy that contains the dimension a ragged hierarchy.
 * The hierarchy that contains the dimension is an unnatural hierarchy.
 * The dimension is a relational OLAP (ROLAP) dimension.
 * The dimension is a linked dimension.

Therefore, if all the children of a dimension member are secured for the current user, the CHILDREN_CARDINALITY property still returns the real number of children instead of returning 0.

For more information about the naming schema for SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:

822499 New naming schema for Microsoft SQL Server software update packages

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Keywords: kbsql2005as kbexpertiseadvanced kbfix kbpubtypekc kbqfe kbhotfixserver KB936595

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