FIX: A full-text query that uses CONTAINS or FREETEXT predicate together with the "OR" operator takes a long time to run in SQL Server 2008 or in in SQL Server 2008 R2

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Article ID: 2264562 - View products that this article applies to.
Microsoft distributes Microsoft SQL Server 2008 and Microsoft SQL Server 2008 R2 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 2008 or SQL Server 2008 R2 fix release.
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SYMPTOMS

You try to run a full-text query in Microsoft SQL Server 2008 or in Microsoft SQL Server 2008 R2. However, you notice that the query may take a long time to run when the WHERE clause uses one of the following two forms:
  • CONTAINS() OR CONTAINS()
    
  • FREETEXT() OR FREETEXT()
    
    
For example, the following full-text query may take a long time to run:
SELECT COUNT(*) as qualifying_rows FROM T1 parent join T1 child on parent.id = child.id
WHERE FREETEXT(parent.col1, 'AAA') OR FREETEXT(child.col1, 'BBB')

CAUSE

This issue occurs because the query optimizer in SQL Server 2008 does not use an optimal query plan.

RESOLUTION

Cumulative update information

SQL Server 2008 Service Pack 1

The fix for this issue was first released in Cumulative Update 9 for SQL Server 2008 Service Pack 1. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2083921 Cumulative update package 9 for SQL Server 2008 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 2008 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:
970365 The SQL Server 2008 builds that were released after SQL Server 2008 Service Pack 1 was released
Microsoft SQL Server 2008 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2008 Service Pack 1 hotfix to an installation of SQL Server 2008 Service Pack 1. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

After you apply the hotfix, you need to enable trace flag 4199 to enable the fix. You can enable the trace flag by running the "DBCC TRACEON(4199, -1)" command or by using the "-T" startup parameter.

SQL Server 2008 Service Pack 2

The fix for this issue was first released in Cumulative Update 1 for SQL Server 2008 Service Pack 2. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2289254 Cumulative update 1 for SQL Server 2008 Service Pack 2
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 2008 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:
2402659 The SQL Server 2008 builds that were released after SQL Server 2008 Service Pack 2 was released

SQL Server 2008 R2

The fix for this issue was first released in Cumulative Update 4. For more information about how to obtain this cumulative update package for SQL Server 2008 R2, click the following article number to view the article in the Microsoft Knowledge Base:
2345451 Cumulative Update package 4 for SQL Server 2008 R2
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 2008 R2 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:
981356 The SQL Server 2008 R2 builds that were released after SQL Server 2008 R2 was released

WORKAROUND

To work around this issue, use the "UNION" operator to rewrite the query instead of using CONTAINS or FREETEXT together with the "OR" operator.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

REFERENCES

For more information about CONTAINS and FREETEXT clause, visit the following Microsoft Developer Network (MSDN) website:
CONTAINS (Transact-SQL)
CFREETEXT (Transact-SQL)
For more information about the Incremental Servicing Model for SQL Server, click the following article number to view the article in the Microsoft Knowledge Base:
935897 An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problems
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

Properties

Article ID: 2264562 - Last Review: November 15, 2010 - Revision: 6.0
APPLIES TO
  • Microsoft SQL Server 2008 R2 Datacenter
  • Microsoft SQL Server 2008 R2 Developer
  • Microsoft SQL Server 2008 R2 Enterprise
  • Microsoft SQL Server 2008 R2 Standard
Keywords: 
kbqfe kbfix kbexpertiseadvanced kbsurveynew KB2264562

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