Question

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，它需要3.5秒以上。

我已阅读（Why is a UDF so much slower than a subquery?），但我正在努力解决/重写问题。

Per @JasonALong的反馈如下，

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

在下面粘贴的3.5秒内完成的功能代码和此链接的执行计划：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

Answer 1

标量函数和muli语句表值函数（mTVF）都在你的问题中提到，＆＃34;黑盒＆＃34;到优化器...

所以，我问的是，＆＃34;为什么这么糟糕？＆＃34;。答案是，为了提出一个尽可能高效执行的好计划，它需要知道有关具体要求的某些细节以及有关从中提取数据的表格的信息（这就是为什么过时的静态可以严重影响性能）。因此......当您使用标量函数或mTVF时，优化程序无法以内联代码的方式评估所有要求。它的回应是简单地假设该函数只执行一次，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，最终会导致糟糕的表现。

解决方案是重写违规函数......关键是＃1，确保将它们重写为＆＃34;内联表值函数＆＃34; （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（因此术语＆＃34;内联＆＃34;）。如果您不熟悉iTVF，他们有2个要求...... 1他们必须是桌面功能（无论出于何种原因，MS STILL还没有提供标量版本......）...... 2这是大问题......函数体必须是单个语句。

那么，如果您不需要表值函数，那么您需要一个标量函数吗？那么，没有任何东西可以说多值函数不能返回单个（标量）值......这就是为什么那些知道这些情况的代码将所有函数作为iTVF。

好消息是网上有关于创建＆＃34;内联标量函数＆＃34;的信息并不缺少，使用编码的表函数来返回网络上的标量值。

希望这有助于......

Answer 2

使用联接代替＆＃34; IN＆＃34;条款帮助很大。（虽然我也将表变量更改为临时表，这也有很大帮助。）

慢速UDF的SQL替代方案

2 个答案: