KB2499023 - FIX: Incorrect results when a complex update query uses the JOIN operator in an execution plan in SQL Server 2008 or in SQL Server 2008 R2

Symptoms

When you run a complex update query that uses the JOIN operator in an execution plan in Microsoft SQL Server 2008 or in Microsoft SQL Server 2008 R2, you may receive incorrect results.

Note The update query might contain subqueries, aggregate functions, and the DISTINCT clause.

If you run the same query in Microsoft SQL Server 2008 or in Microsoft SQL Server 2008 R2 Parallel Data Warehouse, you may receive another set of incorrect results. For example, you might receive incorrect results when you run the following code:

UPDATE RB SET rb1 = (SELECT AVG(DISTINCT T2_1.C1) AS C1 FROM (SELECT DISTINCT T3_1.C3 AS C1, T3_1.C5 AS C2 FROM (SELECT T5_1.c2 AS C1, T5_1.c2 AS C2, T5_1.c3 AS C3, T5_1.c3 AS C4, T5_1.c2 AS C5 FROM DC AS T5_1 UNION SELECT T5_1.c2 AS C1, T5_1.c3 AS C2, T5_1.c2 AS C3, T5_1.c2 AS C4, T5_1.c3 AS C5 FROM DC AS T5_1) AS T3_1) AS T2_1 WHERE (T2_1.C1 = rb3)), rb2 = (SELECT COUNT_BIG(DISTINCT T2_1.C1) AS C1 FROM (SELECT DISTINCT T3_1.C1 AS C1 FROM (SELECT T5_1.rc2 AS C1 FROM RC AS T5_1 UNION ALL SELECT T5_1.c3 AS C1 FROM DC AS T5_1) AS T3_1) AS T2_1 WHERE (T2_1.C1 > rb1)), rb3 = (SELECT COUNT_BIG(*) AS C1 FROM (SELECT DISTINCT T3_1.C1 AS C1, T3_1.C2 AS C2, T3_1.C3 AS C3, T3_1.C4 AS C4, T3_1.C5 AS C5, T3_1.C6 AS C6, T3_1.C7 AS C7, T3_1.C8 AS C8, T3_1.C9 AS C9, T3_1.C10 AS C10 FROM (SELECT T5_1.b2 AS C1, T5_1.b1 AS C2, T5_1.b3 AS C3, T5_1.b2 AS C4, T5_1.b2 AS C5, T5_1.b2 AS C6, T5_1.b2 AS C7, T5_1.b1 AS C8, T5_1.b2 AS C9, T5_1.b3 AS C10 FROM DB AS T5_1 UNION SELECT T5_1.ra3 AS C1, T5_1.ra3 AS C2, T5_1.ra3 AS C3, T5_1.ra3 AS C4, T5_1.ra2 AS C5, T5_1.ra3 AS C6, T5_1.ra1 AS C7, T5_1.ra1 AS C8, T5_1.ra1 AS C9, T5_1.ra1 AS C10 FROM RA AS T5_1) AS T3_1) AS T2_1 WHERE (T2_1.C2 <= rb3)) WHERE rb1 IN (SELECT T2_1.C1 AS C1 FROM (SELECT T4_1.a2 AS C1, T4_1.a1 AS C2, T4_1.a1 AS C3, T4_1.a2 AS C4, T4_1.a1 AS C5, T4_1.a2 AS C6, T4_1.a3 AS C7, T4_1.a1 AS C8 FROM DA AS T4_1 WHERE (T4_1.a1 > (SELECT MIN(DISTINCT T5_1.b3) AS C1 FROM DB AS T5_1 WHERE (T5_1.b3 <= T4_1.a1))) UNION ALL SELECT T4_1.a2 AS C1, T4_1.a2 AS C2, T4_1.a1 AS C3, T4_1.a1 AS C4, T4_1.a1 AS C5, T4_1.a1 AS C6, T4_1.a1 AS C7, T4_1.a3 AS C8 FROM DA AS T4_1) AS T2_1);

Cause

This issue occurs because of an error in the SQL Server query optimizer.

Resolution

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 Parallel Data Warehouse, visit the following Microsoft website:

General information about Parallel Data WarehouseFor 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 problemsFor 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 packagesFor 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