FIX: You may notice a decrease in performance when you run a query that uses the UNION ALL operator in SQL Server 2000 Service Pack 4

Consider the following scenario. You upgrade from Microsoft SQL Server 2000 Service Pack 3 (SP3) to Microsoft SQL Server 2000 Service Pack 4 (SP4). Then, you run a query that uses the UNION ALL operator. In this scenario, you may notice a decrease in performance.

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