使用子查询时如何提高查询性能

Question

查询的第一部分获取Policy 的Premiums、Effective 和Expiration 日期。 第二部分创建Calendar，第三部分（最终SELECT 声明）返回按Month 和Year 细分的收益 一切正常，只需 3 秒即可显示结果。 但是然后我需要过滤PolicyNumbers 可以使用的内容，基本上我需要摆脱没有@ClassCode 的PolicyNumber。因此，在查询的第一部分中，我放置了WHERE 子句：

WHERE  State IN ('CA','NV','AZ')        
        AND PolicyNumber IN (
                            SELECT  PolicyNumber
                            FROM    tblClassCodesPlazaCommercial 
                            GROUP BY PolicyNumber
                            HAVING COUNT (CASE WHEN ClassCode NOT IN (@ClassCode)                                                                       
 THEN 1 END)=0
                            )

感谢@Prdp 用户，我有这样的声明：Case 语句将为列表中存在的 ClassCode 生成 1，否则将生成 NULL。现在计数聚合将为每个 PolicyNumber 计数 1。通过设置 = 0，我们可以确保 PolicyNumber 在给定列表中没有任何 ClassCode。

在该查询永远旋转之后，因为@ClassCode 在 SSRS 报告中可以有超过 200 个ClassCodes。

有趣的是，这两个语句分别可以正常工作。但是当我一起使用它们时（将WHERE 子句放在cte policy_data 中，那么执行将永远存在。 有什么方法可以告诉引擎执行查询的第一部分，即

; WITH Earned_to_date AS (
   SELECT Cast(EOMONTH (GETDATE(), -1) AS DATE) AS Earned_to_date
), policy_data AS (
    SELECT
        PolicyNumber
,       Cast(PolicyEffectiveDate AS DATE) AS PolicyEffectiveDate
,       Cast(PolicyExpirationDate AS DATE) AS PolicyExpirationDate
,       WrittenPremium
,       State
        FROM PlazaInsuranceWPDataSet
        WHERE  State IN ('CA','NV','AZ') 
    /* -------This statement gives me trouble ----------------------*/
        AND PolicyNumber IN (
                            SELECT  PolicyNumber
                            FROM    tblClassCodesPlazaCommercial 
                            GROUP BY PolicyNumber
                            HAVING COUNT (CASE WHEN ClassCode NOT IN (5151)                                                                     
 THEN 1 END)=0
                            )
)

然后仅计算和分解那些已过滤的保单的收益。

我的整个代码如下：

; WITH Earned_to_date AS (
   SELECT Cast(EOMONTH (GETDATE(), -1) AS DATE) AS Earned_to_date
), policy_data AS (
    SELECT
        PolicyNumber
,       Cast(PolicyEffectiveDate AS DATE) AS PolicyEffectiveDate
,       Cast(PolicyExpirationDate AS DATE) AS PolicyExpirationDate
,       WrittenPremium
,       State
        FROM PlazaInsuranceWPDataSet
        WHERE  State IN ('CA','NV','AZ') 
    /* -------This statement gives me trouble ----------------------*/
        AND PolicyNumber IN (
                            SELECT  PolicyNumber
                            FROM    tblClassCodesPlazaCommercial 
                            GROUP BY PolicyNumber
                            HAVING COUNT (CASE WHEN ClassCode NOT IN (@ClassCode)                                                                       
 THEN 1 END)=0
                            )
)
, digits AS (
SELECT digit
   FROM (VALUES (0), (1), (2), (3), (4)
,      (5), (6), (7), (8), (9)) AS z2 (digit)
), numbers AS (
SELECT 1000 * d4.digit + 100 * d3.digit + 10 * d2.digit + d1.digit AS number
    FROM digits AS d1
    CROSS JOIN digits AS d2
    CROSS JOIN digits AS d3
    CROSS JOIN digits AS d4
), calendar AS (
SELECT
    DateAdd(month, number, '1753-01-01') AS month_of
,   DateAdd(month, number, '1753-02-01') AS month_after
    FROM numbers
), policy_dates AS (
SELECT
   PolicyNumber
,   CASE
        WHEN month_of < PolicyEffectiveDate THEN PolicyEffectiveDate
        ELSE month_of
    END AS StartRiskMonth
,   CASE
       WHEN PolicyExpirationDate < month_after THEN PolicyExpirationDate
       WHEN Earned_to_date.Earned_to_date < month_after THEN Earned_to_date
       ELSE month_after
    END AS EndRiskMonth
,   DateDiff(day, PolicyEffectiveDate, PolicyExpirationDate) AS policy_days
,   WrittenPremium
    FROM policy_data
    JOIN calendar
        ON (policy_data.PolicyEffectiveDate < calendar.month_after
        AND calendar.month_of < policy_data.PolicyExpirationDate)
    CROSS JOIN Earned_to_date
    WHERE  month_of < Earned_to_date
)
SELECT      
            Year(StartRiskMonth) as YearStartRisk, 
            Month(StartRiskMonth) as MonthStartRisk,
            c.YearNum,c.MonthNum,
            convert(varchar(7), StartRiskMonth, 120) as RiskMonth,
            sum(WrittenPremium * DateDiff(day, StartRiskMonth, EndRiskMonth) / policy_days) as EarnedPremium
FROM        tblCalendar  c
            LEFT  JOIN policy_dates l ON c.YearNum=Year(l.StartRiskMonth) AND c.MonthNum = Month(l.StartRiskMonth) 
            AND l.StartRiskMonth BETWEEN '01-01-2015' AND  '12-31-2016'
WHERE       c.YearNum Not IN (2017) 
GROUP BY    convert(varchar(7), StartRiskMonth, 120),
            Year(StartRiskMonth) , Month(StartRiskMonth),
            c.YearNum,c.MonthNum
ORDER BY    c.YearNum,c.MonthNum

提高性能的最佳方法是什么？ 我在两个表的PolicyNumber 上创建了non-clustered 索引。但还是一无所获。 就像我说的，在我看来，如果 SQL 引擎将处理需要 3 秒的第一部分（PolicyNumber 过滤），然后再执行需要 3 秒的第二部分（计算那些 PolicyNumber） - 那将是非常棒的。 但我是 DBA 的新手，所以我不确定它是否可能。 有什么建议吗？ 谢谢

执行计划::

最终结果：

Answer 1

您必须使您的代码更具可读性。通过临时表而不是 cte 将其拆分为更小的块。

你的麻烦：

HAVING COUNT (CASE WHEN ClassCode NOT IN (5151) THEN 1 END)=0

如果您的 HAVING COUNT (TRUE -> 1) 中的 ClassCode 为 5000。

如果您的 HAVING COUNT (FALSE -> NULL) 中的 ClassCode 为 5151。

应该在分组前过滤：

WHERE ClassCode IN (5151) -- and check index