Consider the following scenario:
- In Microsoft SQL Server 2005, you have a table that has a foreign key constraint.
- You run an INSERT statement to insert many rows into this table.
- The execution plan for the INSERT statement contains a merge join operation.
In this scenario, the insert operation may fail. Additionally, you receive the following error message:
Error: 547, Severity: 16, State: 0
The INSERT statement conflicted with the FOREIGN KEY constraint "<foreign key>".
The conflict occurred in database "<database name>", table "<table name>", column '<column name>'
The merge join operation expects to receive the rows that are sorted according to the join columns. However, in the situation that is mentioned in the "Symptoms" section, the merge join operation does not receive the inserted rows in the correct order. This problem occurs because the execution plan reads new rows from an index whose keys correspond to the join columns. However, SQL Server reads the index in allocation order instead of in key order.
The fix for this issue was first released in Cumulative Update 7 for SQL Server 2005 Service Pack 3. For more information about this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
Cumulative update package 7 for SQL Server 2005 Service Pack 3
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 2005 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:
The SQL Server 2005 builds that were released after SQL Server 2005 Service Pack 3 was released
Microsoft SQL Server 2005 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2005 Service Pack 3 hotfix to an installation of SQL Server 2005 Service Pack 3. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.
To work around this problem, use one of the following methods.Method 1
Apply a LOOP JOIN query hint to disable the merge join operation.Method 2
Add an explicit ORDER BY clause to sort rows in the key columns of the index that you are scanning.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
After you apply the hotfix, the index will be read in key order.
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:
An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problems
For more information about how to obtain SQL Server 2005 Service Pack 3, click the following article number to view the article in the Microsoft Knowledge Base:
How to obtain the latest service pack for SQL Server 2005
For more information about new features and improvements in SQL Server 2005 Service Pack 3, visit the following Microsoft Web site:
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:
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:
Description of the standard terminology that is used to describe Microsoft software updates