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

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.

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: This metadata fetch will occur only if the programmer does not explicitly bind the parameter.

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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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, contact 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 Web site: 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.

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

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.

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

For additional information, click the following article number to view the article in the Microsoft Knowledge Base: