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FIX: Incorrect results when you run a parallel query that uses a columnstore index in SQL Server 2012

Article ID: 2703193 - View products that this article applies to.

Symptoms

When you run a parallel query in Microsoft SQL Server 2012, you may receive incorrect results. This problem occurs if the following conditions are true:

The query runs against a partitioned table that has a columnstore index.
The query uses an aggregate function over the columnstore index.

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Cause

This issue occurs when parallel threads are not synchronized. In this situation, when SQL Server computes a bitmap of partitions to scan, partitions are eliminated unexpectedly.

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The fix for this issue was first released in Cumulative Update 1. For more information about how to obtain this cumulative update package for SQL Server 2012 Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base:

2765331

(http://support.microsoft.com/kb/2765331/ )

Cumulative update package 1 for SQL Server 2012 Service Pack 1

Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2012 fix release. We recommend that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

2772858

(http://support.microsoft.com/kb/2772858/ )

The SQL Server 2012 builds that were released after SQL Server 2012 Service Pack 1 was released

SQL Server 2012

The fix for this issue was first released in Cumulative Update 3 for SQL Server 2012. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:

2723749

(http://support.microsoft.com/kb/2723749/LN/ )

Cumulative update package 3 for SQL Server 2012

Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2012 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

2692828

(http://support.microsoft.com/kb/2692828/LN/ )

The SQL Server 2012 builds that were released after SQL Server 2012 was released

You must apply a SQL Server 2012 hotfix to an installation of SQL Server 2012.

Hotfix information

A supported hotfix is 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.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if 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. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:

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

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

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must have SQL Server 2012 installed.

Restart requirement

You do not have to restart the computer after you apply the hotfix.

File information

The global 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.

Collapse this tableExpand this table

File name	File version	File size	Date	Time	Platform
Sqlmin.dll	2011.110.2317.0	26,510,744	18-Apr-2012	03:08	x86
Sqlmin.dll	2011.110.2317.0	32,445,848	18-Apr-2012	03:09	x64

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Workaround

To work around this issue, use one of the following methods:

Use one of the following methods to avoid parallelism in the problematic query:
- Add a MAXDOP 1 query hint option.
- Set the MAX Degree of Parallelism configuration option to 1.
Use a query hint to ignore the columnstore index in the problematic query.

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