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sql - 针对包含 7500 万条记录的表优化存储过程查询

问题描述

我有一个AFW_Coverage包含 7500 万行的表。还有另一个AFW_BasicPolInfo包含大约 300 万行的表。

我编写了以下存储过程来从表中获取记录：

CREATE PROCEDURE [ams360].[GetPolicyCoverages]
    @PageStart INT = 0,
    @PageSize INT = 50000,
    @RowVersion TIMESTAMP = NULL
AS
    SET NOCOUNT ON;

    ;WITH LatestCoverage AS
    (
        SELECT 
            PolId,
            MAX(EffDate) AS CoverageEffectiveDate 
        FROM 
            ams360.AFW_Coverage 
        GROUP BY 
            PolId
    ),
    Coverages AS
    (
        SELECT 
            cov.PolId,
            cov.LobId,
            cov.CoverageId,
            cov.EffDate, 
            cov.CoverageCode,
            cov.isCoverage,
            cov.FullTermPrem,
            cov.Limit1,
            cov.Limit2,
            cov.Limit3,
            cov.Deduct1,
            cov.Deduct2,
            cov.Deduct3,
            cov.ChangedDate,
            cov.RowVersion,
        FROM
            ams360.AFW_Coverage cov
        INNER JOIN
            LatestCoverage mcov ON cov.PolId = mcov.PolId
                                AND cov.EffDate = mcov.CoverageEffectiveDate
        WHERE
            cov.Status IN ('A', 'C')
    )
    SELECT
        BPI.PolId,
        BPI.PolEffDate,
        BPI.PolExpDate,
        BPI.PolTypeLOB,
        cov.LobId,
        cov.CoverageId,
        cov.EffDate,
        cov.CoverageCode,
        cov.isCoverage,
        cov.FullTermPrem,
        cov.Limit1,
        cov.Limit2,
        cov.Limit3,
        cov.Deduct1,
        cov.Deduct2,
        cov.Deduct3,
        cov.ChangedDate,
        cov.RowVersion,
    FROM 
        ams360.AFW_BasicPolInfo BPI 
    INNER JOIN 
        Coverages cov ON bpi.PolId = cov.PolId
    WHERE 
        BPI.Status IN ('A','C')
        AND BPI.PolTypeLOB IN ('Homeowners', 'Dwelling Fire')
        AND BPI.PolSubType = 'P'
        AND BPI.RenewalRptFlag IN ('A', 'R', 'I', 'N')
        AND GETDATE() BETWEEN BPI.PolEffDate AND BPI.PolExpDate
        AND (@RowVersion IS NULL OR cov.RowVersion > @RowVersion)
    GROUP BY 
        BPI.PolId,
        BPI.PolEffDate,
        BPI.PolExpDate,
        BPI.PolTypeLOB,
        cov.LobId,
        cov.CoverageId,
        cov.EffDate,
        cov.CoverageCode,
        cov.isCoverage,
        cov.FullTermPrem,
        cov.Limit1, cov.Limit2, cov.Limit3,
        cov.Deduct1, cov.Deduct2, cov.Deduct3,
        cov.ChangedDate,
        cov.RowVersion,
    ORDER BY 
        cov.RowVersion
    OFFSET 
        @PageStart ROWS
    FETCH NEXT 
        @PageSize ROWS ONLY
GO

但是，我发现上述存储过程以 100% 的速度与数据库挂钩，尽管我添加了以下索引，我看到它们在执行计划中使用：

CREATE NONCLUSTERED INDEX [IX_AFW_Coverage_PolId_EffDate] 
ON [ams360].[AFW_Coverage] ([PolId] ASC, [EffDate] ASC)
            WITH (STATISTICS_NORECOMPUTE = OFF, DROP_EXISTING = OFF, ONLINE = OFF) ON [PRIMARY]
GO

CREATE NONCLUSTERED INDEX [IX_AFW_Coverage_PolId_EffDate_Status_LobId_CoverageId] 
ON [ams360].[AFW_Coverage] ([PolId] ASC, [EffDate] ASC, [Status] ASC, [LobId] ASC, [CoverageId] ASC)
INCLUDE ([CoverageCode], [IsCoverage], [FullTermPrem], [Limit1], [Limit2],[Limit3], [Deduct1], [Deduct2], [Deduct3], [ChangedDate], [RowVersion]) 
        WITH (STATISTICS_NORECOMPUTE = OFF, DROP_EXISTING = OFF, ONLINE = OFF) ON [PRIMARY]
GO

存储过程的执行时间在 6 分钟到 20 分钟或 50 分钟之间变化（取决于服务器流量和使用情况）

我的问题：如何在存储过程中优化此查询，同时记住覆盖表包含 7500 万条记录这一事实？我不是 dba，也没有优化运行缓慢的查询的经验。有关如何解决此问题的任何见解都会有所帮助。提前致谢。

标签： sqlsql-serverdatabase-administration

解决方案

首先，链接公用表表达式可能会导致复杂的执行计划。我们希望计划简单易行，便于引擎优化。

所以，让我们从删除第一个开始：

DROP TABLE IF EXISTS #LatestCoverage;

CREATE TABLE #LatestCoverage
(
    PolId BIGINT PRIMARY KEY
   ,CoverageEffectiveDate DATETIME2(0)
);

INSERT INTO #LatestCoverage
SELECT 
    PolId,
    MAX(EffDate) AS CoverageEffectiveDate 
FROM 
    ams360.AFW_Coverage 
GROUP BY 
    PolId;

如果表中有很多列，ams360.AFW_Coverage则查询列上的索引可能会提高性能：

CREATE INDEX IX_AFW_Coverage_EffDate  ON ams360.AFW_Coverage 
(
    polID
    ,EffDate            
)

然后，您正在阅读大量最近被剪切的数据。您可以尝试高级过滤数据，然后读取行详细信息。像这样的东西：

DROP TABLE if exists #CoveragesFiltered 

CREATE TABLE #CoveragesFiltered
(
     PolId BIGINT PRIMARY KEY
    ,RowVersion ??
);

INSERT INTO #CoveragesFiltered
SELECT 
    cov.PolId,       
    cov.RowVersion,
FROM ams360.AFW_Coverage cov
INNER JOIN #LatestCoverage mcov 
    ON cov.PolId = mcov.PolId
    AND cov.EffDate = mcov.CoverageEffectiveDate
WHERE
    cov.Status IN ('A', 'C')
    AND BPI.Status IN ('A','C')
    AND BPI.PolTypeLOB IN ('Homeowners', 'Dwelling Fire')
    AND BPI.PolSubType = 'P'
    AND BPI.RenewalRptFlag IN ('A', 'R', 'I', 'N')
    AND GETDATE() BETWEEN BPI.PolEffDate AND BPI.PolExpDate
    AND (@RowVersion IS NULL OR cov.RowVersion > @RowVersion)
ORDER BY 
    cov.RowVersion
OFFSET 
    @PageStart ROWS
FETCH NEXT 
    @PageSize ROWS ONLY;

在这里，您可以调试和优化过滤器查询本身，只为您需要的列创建索引。

然后，有需要返回的行，提取它们的详细信息 - 因为我们使用分页，我相信它会表现良好并且花费更少的 IO。

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