您可以将 COUNT DISTINCT 与 OVER 子句一起使用吗？

我正在尝试提高以下查询的性能：

        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupId)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
                   ) r ON r.RuleID = [#TempTable].RuleID AND
                          r.AgentID = [#TempTable].AgentID                            

目前使用我的测试数据大约需要一分钟。我对该查询所在的所有存储过程的更改输入有限，但我可能可以让他们修改这个查询。或者添加索引。我尝试添加以下索引：

CREATE CLUSTERED INDEX ix_test ON #TempTable(AgentID, RuleId, GroupId, Passed)

它实际上使查询花费的时间增加了一倍。我使用非聚集索引获得了相同的效果。

我尝试如下重写它，但没有任何效果。

        WITH r AS (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupId)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
            ) 
        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN r 
            ON r.RuleID = [#TempTable].RuleID AND
               r.AgentID = [#TempTable].AgentID                            

接下来我尝试使用这样的窗口函数。

        UPDATE  [#TempTable]
        SET     Received = COUNT(DISTINCT (CASE WHEN Passed=1 THEN GroupId ELSE NULL END)) 
                    OVER (PARTITION BY AgentId, RuleId)
        FROM    [#TempTable] 

此时我开始收到错误

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near 'distinct'.

所以我有两个问题。首先你不能用 OVER 子句做一个 COUNT DISTINCT 还是我写错了？其次，任何人都可以提出我尚未尝试过的改进建议吗？仅供参考，这是一个 SQL Server 2008 R2 Enterprise 实例。

编辑：这是原始执行计划的链接。我还应该注意，我的大问题是这个查询运行了 30-50 次。

https://onedrive.live.com/redir?resid=4C359AF42063BD98%21772

EDIT2：这是评论中要求的语句所在的完整循环。我正在与定期与此一起工作的人核实循环的目的。

DECLARE @Counting INT              
SELECT  @Counting = 1              

--  BEGIN:  Cascading Rule check --           
WHILE @Counting <= 30              
    BEGIN      

        UPDATE  w1
        SET     Passed = 1
        FROM    [#TempTable] w1,
                [#TempTable] w3
        WHERE   w3.AgentID = w1.AgentID AND
                w3.RuleID = w1.CascadeRuleID AND
                w3.RulePassed = 1 AND
                w1.Passed = 0 AND
                w1.NotFlag = 0      

        UPDATE  w1
        SET     Passed = 1
        FROM    [#TempTable] w1,
                [#TempTable] w3
        WHERE   w3.AgentID = w1.AgentID AND
                w3.RuleID = w1.CascadeRuleID AND
                w3.RulePassed = 0 AND
                w1.Passed = 0 AND
                w1.NotFlag = 1        

        UPDATE  [#TempTable]
        SET     Received = r.Number
        FROM    [#TempTable] 
        INNER JOIN (SELECT  AgentID,
                            RuleID,
                            COUNT(DISTINCT (GroupID)) Number
                    FROM    [#TempTable]
                    WHERE   Passed = 1
                    GROUP BY AgentID,
                            RuleID
                   ) r ON r.RuleID = [#TempTable].RuleID AND
                          r.AgentID = [#TempTable].AgentID                            

        UPDATE  [#TempTable]
        SET     RulePassed = 1
        WHERE   TotalNeeded = Received              

        SELECT  @Counting = @Counting + 1              
    END