Microsoft KB Archive/836830

= FIX: Query performance declines when you use the SET FMTONLY Hint in the Microsoft ODBC Driver for SQL Server and the Microsoft OLE DB Provider for SQL Server =

Article ID: 836830

Article Last Modified on 11/15/2007

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APPLIES TO


 * Microsoft ODBC Driver for Microsoft SQL Server 3.7
 * Microsoft OLE DB Provider for SQL Server
 * Microsoft Data Access Components 2.8
 * Microsoft Data Access Components 2.7 Service Pack 1

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SYMPTOMS
When the Microsoft ODBC Driver for SQL Server and the Microsoft OLE DB provider for SQL Server use the SET FMTONLY Transact-SQL hint to retrieve metadata information for a query, the query may be fully executed. This behavior can affect the performance of the metadata information fetch process.



CAUSE
This problem occurs when an unbound parameter forces the SQL driver to fetch metadata before the actual SQL statement runs. For example, if a client runs the following SQL statement, the SQL driver may require metadata information about the au_id column before the driver runs the actual query and fetches the data: Select * from authors where au_id=? This metadata fetch will occur only if the programmer does not explicitly bind the parameter.



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

File information
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 tool in Control Panel.

MDAC 2.8
  Date         Time   Version         Size     File name -  12-Feb-2004  15:37  2000.81.9044.0   61,440  Dbnetlib.dll 12-Feb-2004 15:34  2.71.9044.0     126,976  Msdart.dll 12-Feb-2004 15:34  3.520.9044.0    204,800  Odbc32.dll 12-Feb-2004 15:38  2000.81.9044.0   24,576  Odbcbcp.dll 12-Feb-2004 15:38  3.520.9044.0     98,304  Odbccp32.dll 12-Feb-2004 15:35  2.71.9044.0     417,792  Oledb32.dll 12-Feb-2004 15:37  2000.81.9044.0  471,040  Sqloledb.dll 12-Feb-2004 15:37  2000.81.9044.0  385,024  Sqlsrv32.dll



Notice
This hotfix is available as part of a cumulative hotfix package. When you receive this hotfix from Microsoft Product Support Services, the article number that is listed in the hotfix package will be 839801 for MDAC 2.8 or 836799 for MDAC 2.7 SP1. For more information, see the following article in the Microsoft Knowledge Base:

MDAC 2.8

839801 FIX: Hotfixes are available for MDAC 2.8

MDAC 2.7 SP1

836799 FIX: Hotfixes are available for MDAC 2.7 Service Pack 1



WORKAROUND
To work around this problem, bind all parameters before you run a SQL statement with the SQL driver. Any unbound parameter will force the SQL driver to fetch metadata before it runs the actual SQL statement.

Note We recommend that you explicitly bind all parameters to optimize performance with the SQL drivers and Microsoft SQL Server.



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
For additional information, 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: kbqfe kbhotfixserver kbfix kbbug kbmdac270presp2fix KB836830

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