FIX: Parallel Hash Join with Empty Result Set Incorrectly Flows Error Back on Client Connection (259021)

SYMPTOMS

If you run a SQL Server Data Manipulation Language (DML) statement from a DB-Library based application against a Microsoft SQL Server 7.0 server, the error handler for the application may incorrectly fire and only report the following error message:

DB-LIBRARY Error 10007, Severity 5:
General SQL Server error: Check messages from the SQL Server.

Note that this error message accompanies a wide range of SQL Server errors that are reported back to the client from the server. However, in this scenario the preceding error message is the only error reported and it is not accompanied by any other specific error messages.

CAUSE

If a parallel hash join produces an empty result set, internal exception 3602 is used to coordinate the shutdown of worker threads that were created to process the parallel hash plan. The internal 3602 exception is an internal control exception that is used to direct processing flow inside SQL Server and is expected behavior in this case.

However, the fact that it is causing an error to be sent back on the client connection, which in turn causes the DB-Library error handler to fire is not expected behavior.

WORKAROUND

Here are two ways you can work around this problem:

Disable the creation of a parallel plan by using a statement level hint for the statement that is experiencing the problem. For example:
```
 "OPTION (MAXDOP 1)"
```
-or-
Disable parallel plan generation globally for the entire server by setting the max degree of parallelism option to 1 through the sp_configure system stored procedure. NOTE: To disable parallel plan generation through the sp_configure system stored procedure, you must enable the show advanced options configuration setting:
```
sp_configure 'show advanced options', 1
reconfigure with override
go
sp_configure 'max degree of parallelism', 1
reconfigure with override
go
```

STATUS

Microsoft has confirmed this to be a problem in SQL Server 7.0. This problem has been corrected in U.S. Service Pack 3 for Microsoft SQL Server 7.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

274799 INF: How to Obtain Service Pack 3 for Microsoft SQL Server 7.0 and Microsoft Data Engine (MSDE) 1.0

For more information, contact your primary support provider.

MORE INFORMATION

This problem is not experienced by ODBC or OLE DB clients.

REFERENCES

SQL Server 7.0 Books Online; topics: "Show advanced options"; "max degree of parallelism system configuration settings"; "MAXDOP"