硬删除与软删除性能

Question

我有这张桌子，打算有很多活动。其中的任何内容都表明用户操作仍在等待中。一旦删除，它将表明该操作不再处于待处理状态。系统的其他区域依赖于此，因此表格本身并不能真正解释这种情况。但是，我的问题是我是否应该保持表原样并删除，当挂起的操作完成时，或者我是否应该添加一个标志列并更新。

请注意，记录可能会在插入的同一秒内被删除。我希望每秒最多支持 100 个，但不希望将其作为限制。

我使用的是 SQL Server 2014 企业版。

这是表的定义（所有索引都基于使用此表的选择查询）：

CREATE TABLE [dbo].[OpenRounds](
    [OpenRoundId] [bigint] IDENTITY(1,1) NOT NULL,
    [UserId] [int] NOT NULL,
    [GameActivityId] [bigint] NOT NULL,
    [VendorId] [int] NOT NULL,
    [Date] [datetime] NOT NULL,
    [UserBonusId] [bigint] NULL,
    [VendorRoundId] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_GamesOpenRounds] PRIMARY KEY CLUSTERED 
(
    [OpenRoundId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

CREATE NONCLUSTERED INDEX [IX_GameOpenRoundsUserIdUserBonusId] ON [dbo].[OpenRounds]
(
    [UserId] ASC,
    [UserBonusId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
GO

CREATE NONCLUSTERED INDEX [IX_GameOpenRoundsUserIdVendorIdVendorRoundId] ON [dbo].[OpenRounds]
(
    [UserId] ASC,
    [VendorId] ASC,
    [VendorRoundId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
GO

CREATE NONCLUSTERED INDEX [IX_GameOpenRoundsVendorIdVendorRoundId] ON [dbo].[OpenRounds]
(
    [VendorId] ASC,
    [VendorRoundId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON)
GO

Answer 1

如果您设计系统的目的是支持每秒数千个事务，您可能希望设计一个不依赖于插入的排队系统。插入的成本很高，并且取决于队列表的设计，可能会导致队列表的最后一页成为限制系统吞吐量速率的“热点”。

以下设计允许通过 Rounds 表进行多达 100,000 个并发事务。

CREATE TABLE dbo.OpenRounds
(
    OpenRoundID BIGINT NOT NULL
        CONSTRAINT PK_GamesOpenRounds 
        PRIMARY KEY CLUSTERED
    , UserID INT NULL
    , GameActivityID BIGINT NULL
    , VendorID INT NULL
    , RoundDate DATETIME NULL
    , UserBonusID BIGINT NULL
    , VendorRoundID NVARCHAR(50) NULL
    , ReferenceCount INT NOT NULL
        CONSTRAINT DF_OpenRounds_ReferenceCount
        DEFAULT ((0))
);

INSERT INTO dbo.OpenRounds (OpenRoundID)
SELECT TOP(100000) /* top 100,000 -> we're creating 100,000 slots */
    rn = ROW_NUMBER() OVER (ORDER BY o1.object_id)
FROM sys.objects o1
    , sys.objects o2
    , sys.objects o3;

GO
CREATE SEQUENCE dbo.RoundSlotSequence
AS INT
START WITH 1
INCREMENT BY 1
MINVALUE 1
MAXVALUE 100000
CYCLE
CACHE 10000;
GO

上面创建的序列设计为在达到 100,000 后滚动。这与我们在dbo.OpenRounds表中创建的行数一致。

要将消息推送到 OpenRounds 表中，您可以使用以下过程：

CREATE PROCEDURE dbo.PushRound
(
    @UserID INT
    , @GameActivityID BIGINT
    , @VendorID INT
    , @RoundDate DATETIME
    , @UserBonusID BIGINT
    , @VendorRoundID NVARCHAR(50)
)
AS
BEGIN
    DECLARE @SlotID INT;
    DECLARE @SequenceID INT;
    DECLARE @TryCount INT = 0;
    SELECT @SequenceID = NEXT VALUE FOR dbo.RoundSlotSequence;
    WHILE @SlotID IS NULL AND @TryCount < 50
    BEGIN
        UPDATE dbo.OpenRounds WITH (ROWLOCK)
        SET ReferenceCount = ReferenceCount + 1
            , @SlotID = OpenRoundID
            , UserID = @UserID
            , GameActivityID = @GameActivityID
            , VendorID = @VendorID
            , RoundDate = @RoundDate
            , UserBonusID = @UserBonusID
            , VendorRoundID = @VendorRoundID
        WHERE ReferenceCount = 0
            AND OpenRoundID = @SequenceID;
        /* If @SlotID IS NULL the slot was not available
            - wait 5 milliseconds before checking again 
            to see if the slot is open
        */
        IF @SlotID IS NULL WAITFOR DELAY '00:00:00.005';
        SET @TryCount += 1;
    END
    IF @SlotID IS NULL
        RETURN 1
    ELSE 
        RETURN @SlotID
END;
GO

此过程可用于从 OpenRounds 表中获取下一条消息。通常，这将在一个循环内运行，该循环不断寻找要处理的行：

CREATE PROCEDURE dbo.PopRound
(
    @UserID INT OUTPUT
    , @GameActivityID BIGINT OUTPUT
    , @VendorID INT OUTPUT 
    , @RoundDate DATETIME OUTPUT
    , @UserBonusID BIGINT OUTPUT
    , @VendorRoundID NVARCHAR(50) OUTPUT
    , @MaxRetries INT = 2000 /* 10 seconds 
                default maximum wait time */
)
AS
BEGIN
    DECLARE @SlotID INT;
    DECLARE @TryCount INT = 0;
    WHILE @SlotID IS NULL AND @TryCount < @MaxRetries
    BEGIN
        UPDATE dbo.OpenRounds WITH (ROWLOCK)
        SET ReferenceCount = ReferenceCount - 1
            , @SlotID = OpenRoundID
            , @UserID = UserID
            , @GameActivityID = GameActivityID
            , @VendorID = VendorID
            , @RoundDate = RoundDate
            , @UserBonusID = UserBonusID
            , @VendorRoundID = VendorRoundID
        WHERE ReferenceCount > 0;
        IF @SlotID IS NULL WAITFOR DELAY '00:00:00.005';
        SET @TryCount += 1;
    END
END;
GO

这种设计大致基于我在Exadat.co.uk超级扩展 SQL Server 站点上看到的概念，作者是 Chris Adkin。他的站点提供了关于将 SQL Server 推向极限的出色材料和指导，包括有关硬件以及 SQL Server 如何与其交互的非常深入的详细信息。我与 Chris 或他的网站没有任何关联。