慢速 UDF 的 SQL 替代方案

Question

慢速 UDF 的 SQL 替代方案

Mik*_*e S 0 sql-server stored-procedures user-defined-functions user-defined-types

具有两个 UDT 参数的查询需要 0.3 秒，但是当封装在内联表值函数中时，需要 3.5 秒以上。

根据下面@JasonALong 的反馈，

0.3 秒内完成的 SELECT 语句的执行计划： https://www.brentozar.com/pastetheplan/? id=HJnrqC53Z（请注意，此页面上提供了 SQL）。

下面粘贴了在 3.5 秒内完成的函数代码以及此链接中的执行计划：https://www.brentozar.com/pastetheplan/ ?id=BJZbqR93b

SELECT
SelectedContracts.MeasurableID,
SelectedContracts.EntityID,

EntityName,
EntityAbbrev,
EntityLogoURL,
EntityHex1,
EntityHex2,
EntitySportID,

MeasurableName,
MeasurableOrganizationID,
YearFilter,
SeasonFilter,
CategoryFilter,
ResultFilter,
Logo4Result,
MeasurableSportID,
MouseoverFooter,
ContractRank4Org,
ContractEndUTC,

HighContractPrice4Period,
HighTradeID,
HighTradeUTC,
HighTradeNumberOfContracts,
HighTradeCurrency,

LowContractPrice4Period,
LowTradeID,
LowTradeUTC,
LowTradeNumberOfContracts,
LowTradeCurrency,

LastTradePrice,
LastTradeID,
LastTradeUTC,
LastTradeNumberOfContracts,
LastTradeCurrency,

SecondLastTradePrice,
SecondLastTradeID,
SecondLastTradeUTC,
SecondLastTradeNumberOfContracts,
SecondLastTradeCurrency,

ContractPrice4ChangeCalc,
ContractID4ChangeCalc,
ContractUTC4ChangeCalc,
ContractsNumberTraded4ChangeCalc,
ContractCurrency4ChangeCalc,

HighestBidID,
HighestBidMemberID,
HighestBidPrice,
HighestBidAvailableContracts,
HighestBidCurrency,

LowestAskID,
LowestAskMemberID,
LowestAskPrice,
LowestAskAvailableContracts,
LowestAskCurrency


FROM
(
    SELECT
        dbo.Contracts.MeasurableID,
        dbo.Contracts.EntityID
    FROM
        dbo.Contracts
    WHERE
        dbo.Contracts.MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
    GROUP BY
        dbo.Contracts.MeasurableID,
        dbo.Contracts.EntityID
) SelectedContracts


INNER JOIN 
(
    SELECT
        dbo.Entities.ID,
        --dbo.Entities.OrganizationID, -- Get OrganizationID from Measurable since some Entities (European soccer teams) have multiple Orgs
        dbo.Entities.EntityName,
        dbo.Entities.EntityAbbrev,
        dbo.Entities.logoURL AS EntityLogoURL,
        dbo.Entities.Hex1 AS EntityHex1,
        dbo.Entities.Hex2 AS EntityHex2,
        dbo.Entities.SportID AS EntitySportID
    FROM
        dbo.Entities
) SelectedEntities ON SelectedContracts.EntityID = SelectedEntities.ID


INNER JOIN 
(
    SELECT
        dbo.Measurables.ID AS MeasurableID,
        dbo.Measurables.Name AS MeasurableName,
        dbo.Measurables.OrganizationID AS MeasurableOrganizationID,
        dbo.Measurables.[Year] AS YearFilter,
        dbo.Measurables.Season AS SeasonFilter,
        dbo.Measurables.Category AS CategoryFilter,
        dbo.Measurables.Result AS ResultFilter,
        dbo.Measurables.Logo4Result,
        dbo.Measurables.SportID AS MeasurableSportID,
        dbo.Measurables.MouseoverFooter,
        dbo.Measurables.ContractRank4Org,
        dbo.Measurables.EndUTC AS ContractEndUTC
    FROM
        dbo.Measurables
) MEASURABLES_table ON SelectedContracts.MeasurableID = MEASURABLES_table.MeasurableID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ContractPrice AS HighContractPrice4Period,
        ID AS HighTradeID,
        UTCMatched AS HighTradeUTC,
        NumberOfContracts AS HighTradeNumberOfContracts,
        CurrencyCode AS HighTradeCurrency
    FROM
                (
                    SELECT
                        *, ROW_NUMBER () OVER (
                            PARTITION BY MeasurableID,
                            EntityID
                        ORDER BY
                            ContractPrice DESC,
                            ID DESC
                        ) RowNumber -- ID DESC means most recent trade of ties
                    FROM
                        Contracts
                    WHERE
                        MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                        AND dbo.Contracts.UTCmatched < DATEADD(DAY, -30, SYSDATETIME())
                        AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                                )   
                ) AS InnerSelect4HighTrade

    WHERE   
        InnerSelect4HighTrade.RowNumber = 1

) HighTrades ON SelectedContracts.MeasurableID = HighTrades.MeasurableID AND SelectedContracts.EntityID = HighTrades.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ContractPrice AS LowContractPrice4Period,
        ID AS LowTradeID,
        UTCMatched AS LowTradeUTC,
        NumberOfContracts AS LowTradeNumberOfContracts,
        CurrencyCode AS LowTradeCurrency
    FROM
        (
            SELECT
                    *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    ContractPrice ASC,
                    ID DESC
                ) RowNumber -- ID DESC means most recent trade of ties
            FROM
                Contracts
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                AND dbo.Contracts.UTCmatched < DATEADD(DAY, -30, SYSDATETIME())
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )           
        ) AS InnerSelect4LowTrade

    WHERE       InnerSelect4LowTrade.RowNumber = 1

) LowTrades ON SelectedContracts.MeasurableID = LowTrades.MeasurableID AND SelectedContracts.EntityID = LowTrades.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ContractPrice AS LastTradePrice,
        ID AS LastTradeID,
        UTCMatched AS LastTradeUTC,
        NumberOfContracts AS LastTradeNumberOfContracts,
        CurrencyCode AS LastTradeCurrency
    FROM
        (
            SELECT
                *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    ID DESC
                ) RowNumber -- ID DESC means most recent trade of ties
            FROM
                Contracts
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )   
        ) AS InnerSelect4LastTrade

    WHERE   InnerSelect4LastTrade.RowNumber = 1

) LastTrades ON SelectedContracts.MeasurableID = LastTrades.MeasurableID AND SelectedContracts.EntityID = LastTrades.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ContractPrice AS SecondLastTradePrice,
        ID AS SecondLastTradeID,
        UTCMatched AS SecondLastTradeUTC,
        NumberOfContracts AS SecondLastTradeNumberOfContracts,
        CurrencyCode AS SecondLastTradeCurrency
    FROM
        (
            SELECT
                *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    ID DESC
                ) RowNumber -- ID DESC means most recent trade of ties
            FROM
                Contracts
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )   
--need time filter???
        ) AS InnerSelect4SecondToLastTrade

    WHERE InnerSelect4SecondToLastTrade.RowNumber = 2

) SecondToLastTrade ON SelectedContracts.MeasurableID = SecondToLastTrade.MeasurableID AND SelectedContracts.EntityID = SecondToLastTrade.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ContractPrice AS ContractPrice4ChangeCalc,
        ID AS ContractID4ChangeCalc,
        UTCMatched AS ContractUTC4ChangeCalc,
        NumberOfContracts AS ContractsNumberTraded4ChangeCalc,
        CurrencyCode AS ContractCurrency4ChangeCalc
    FROM
        (
            SELECT
                *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    ID DESC  -- ID DESC equals the most recent trade if ties
                ) RowNumber 
            FROM
                Contracts
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )   
            AND dbo.Contracts.UTCmatched < DATEADD(Day ,-30, SYSDATETIME())
        ) AS InnerSelect4ChangeCalcPerPeriod

    WHERE   InnerSelect4ChangeCalcPerPeriod.RowNumber = 1

) Trade4ChangeCalcPerPeriod ON SelectedContracts.MeasurableID = Trade4ChangeCalcPerPeriod.MeasurableID AND SelectedContracts.EntityID = Trade4ChangeCalcPerPeriod.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ID AS HighestBidID,
        MemberID AS HighestBidMemberID,
        BidPrice AS HighestBidPrice,
        AvailableContracts AS HighestBidAvailableContracts,
        CurrencyCode AS HighestBidCurrency
    FROM
        (
            SELECT
                *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    BidPrice DESC,
                    ID DESC
                ) RowNumber
            FROM
                dbo.Interest2Buy
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
            AND AvailableContracts > 0
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )   
        ) AS InnerSelect4HighestBid

    WHERE   InnerSelect4HighestBid.RowNumber = 1

) HighestBids ON SelectedContracts.MeasurableID = HighestBids.MeasurableID AND SelectedContracts.EntityID = HighestBids.EntityID


LEFT JOIN 
(
    SELECT
        MeasurableID,
        EntityID,
        ID AS LowestAskID,
        MemberID AS LowestAskMemberID,
        AskPrice AS LowestAskPrice,
        AvailableContracts AS LowestAskAvailableContracts,
        CurrencyCode AS LowestAskCurrency
    FROM
        (
            SELECT
                *, ROW_NUMBER () OVER (
                    PARTITION BY MeasurableID,
                    EntityID
                ORDER BY
                    AskPrice ASC,
                    ID DESC
                ) RowNumber
            FROM
                dbo.Interest2Sell
            WHERE
                MeasurableID IN ((2030),(2017),(2018),(2019),(2020),( 2028),(2024),(2027),(2029),(2022),( 4018),(4019),(4020),(4021))
                AND AvailableContracts > 0
                AND (           CurrencyCode IN (('GBP'), ('CAD'), ('INR'), ('BRL'), ('MXN'), ('CHF'), ('RUB')) 
                        )   
        ) AS InnerSelect4BestAsk

    WHERE   InnerSelect4BestAsk.RowNumber = 1

) BestAsks ON SelectedContracts.MeasurableID = BestAsks.MeasurableID AND SelectedContracts.EntityID = BestAsks.EntityID

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Answer 1

Jas*_*ong 5

正如您的问题中提到的，标量函数和多语句表值函数（mTVF）都是优化器的“黑匣子”......

所以，我的问题是，“为什么这么糟糕？”。答案是，为了制定一个尽可能高效执行的良好计划，它需要了解有关特定需求的某些详细信息以及有关将从中提取数据的表的信息（这就是为什么过时的静态数据可能会被删除）也严重影响性能）。所以...当您使用标量函数或 mTVF 时，优化器无法像使用内联代码那样评估所有需求。它的响应是简单地假设该函数只会执行一次，并根据该假设制定计划。

由于假设是错误的，因此会产生错误的计划，最终导致糟糕的表现。

解决方案是重写有问题的函数...关键是＃1，确保将它们重写为“内联表值函数”（iTVF）。这些是优化器将看到的唯一函数，就好像它们的代码直接输入到外部查询中一样（因此称为“内联”）。如果您不熟悉 iTVF，它们有 2 个要求... 1 它们必须是表函数（无论出于何种原因，MS 仍然没有可用的标量版本）... 2 这是biggie...函数体必须是单个语句。

那么，如果您不需要表值函数，而是需要标量函数怎么办？好吧，没有什么说多值函数不能返回单个（标量）值...这就是为什么那些了解这种情况的人将其所有函数都代码为 iTVF。

好处是，网络上不乏有关创建“内联标量函数”的信息，使用编码为在网络上返回标量值的表函数。

希望这可以帮助...

如果想要验证 SQL Server 是否认为某个特定函数是“内联”的，只需查询 sys.objects 表即可。SELECT * FROM sys.objects o WHERE o.name = N'tfn_SomeFunction'; ...或者...您可以一次查看所有uds... SELECT * FROM sys.objects o WHERE o.type IN ('FN', 'FS', 'IF', 'TF'); (2认同)

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