在 INSERT (..) SELECT.. (SQL-server 2014) 之后得到错误的 @@rowcount

Question

在 M$ SQL server 2014 (v.12.0.4100.1) 中： 我正在尝试使用@@rowcount 将一个表（~3'500'000'000 行）批量复制到另一个表。 两个表在 ([timestamp],[NumericID]) 上都有唯一索引。

问题是，在一些成功的循环之后，我遇到了主键违规，例如：

ErrorNumber ErrorSeverity ErrorState ErrorLine ErrorProcedure ErrorMessage: 2627 14 1 52 NULL 违反主键约束“PK_DataHist_2”。 无法在对象“dbo.DataHist_2”中插入重复键。复制品 键值为（2014 年 7 月 14 日下午 4:27，5011）。

键值总是不同的。错误发生在不同数量的循环后，似乎是随机的。 似乎 SQL 语句 SOMETIMES 返回 @@rowcount = 0。
我不知道为什么会这样。有人可以指出我做错了什么吗？

-- copy data from DataHist to DataHist_2
/* SRC table def:
CREATE TABLE [dbo].[DataHist](
    [ID] [BIGINT] IDENTITY(1,1) NOT NULL,
    [TimeStamp] [DATETIME] NOT NULL,
    [NumericID] [INT] NOT NULL,
    [BadQ] [BIT] NULL CONSTRAINT [DF_DataHist_BadQ]  DEFAULT (NULL),
    [Quality]  AS (CASE ISNULL([BadQ],(0)) WHEN (0) THEN (1) ELSE (0) END),
    [Value]  [VARCHAR](8000)
 CONSTRAINT [PK_DataHist] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)
)
CREATE UNIQUE NONCLUSTERED INDEX [IX_DataHist_Time_NumID] ON [dbo].[DataHist]
(
    [NumericID] ASC,
    [TimeStamp] ASC
) 
*/
/* Dest table:
CREATE TABLE [dbo].[DataHist_2](
[TimeStamp] [datetime] NOT NULL,
[NumericID] [int] NOT NULL,
[Value] [varchar](8000) NULL,
[BadQ] [bit] NULL CONSTRAINT [DF_DataHist_2_BadQ]  DEFAULT (NULL),
[Quality]  AS (case isnull([BadQ],(0)) when (0) then (1) else (0) end),
CONSTRAINT [PK_DataHist_2] PRIMARY KEY CLUSTERED 
(
   [TimeStamp] ASC,
   [NumericID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) -- ON [DataHistFG]
) -- ON [DataHistFG]
*/

BEGIN TRY
SET XACT_ABORT ON;
SET NOCOUNT ON;

PRINT 'copy data from DataHist to DataHist_2';
PRINT GETUTCDATE();

DECLARE @nextID BIGINT = 1;
DECLARE @r INT ,
    @N INT = 1000000;
DECLARE @s VARCHAR(1000);
DECLARE @t0 DATETIME;
SET @r = 1;
-- find where to re-start copying:
SET @nextID = ( SELECT TOP ( 1 )
                        ID
                FROM    dbo.DataHist DH
                WHERE   NOT EXISTS ( SELECT 1
                                     FROM   dbo.DataHist_2 DH2
                                     WHERE  DH.TimeStamp = DH2.TimeStamp
                                            AND DH.NumericID = DH2.NumericID )
                ORDER BY DH.ID
              );

PRINT @nextID;
PRINT GETUTCDATE();
-- insert in batches of @N:
WHILE @r > 0
    BEGIN
        BEGIN TRANSACTION;

        SET @t0 = GETUTCDATE();

        INSERT  INTO dbo.DataHist_2
                ( TimeStamp ,
                  NumericID ,
                  BadQ ,
                  Value
                ) 
                SELECT TOP ( @N )
                        TimeStamp ,
                        NumericID ,
                        BadQ ,
                        Value
                FROM    dbo.DataHist 
                WHERE   ID >= @nextID
                ORDER BY ID 

        SET @r = @@ROWCOUNT;
        SET @nextID = @nextID + @r;
        SET @s = 'nextID=' + CAST(@nextID AS VARCHAR(30)) + ', t='
            + CAST(DATEDIFF(SECOND, @t0, GETUTCDATE()) AS VARCHAR(1000));
        PRINT @s;

        COMMIT TRANSACTION;

END;

PRINT GETUTCDATE();
PRINT 'END';

END TRY
BEGIN CATCH
PRINT 'Catch Exception'
IF @@trancount > 0 
    BEGIN
        PRINT 'Rolling back transaction.';
        ROLLBACK TRANSACTION;
    END;
EXEC usp_GetErrorInfo;
END CATCH;

Answer 1

正如@Shannon Severance 所建议的，问题是源表的“ID 序列中的漏洞”。

通过这种方式设置@nextID解决：

SET @nextID = (SELECT MAX(id)+1 FROM dbo.DataHist_2); -- was: SET @nextID = @nextID + @r;

（ID 列已添加到目标表并从 src 复制。）

谢谢你，香农

Answer 2

老兄，@@rowcount 是正确的，总是等于 1。 请检查此代码以获得更清晰的信息：

-- 将数据从 DataHist 复制到 DataHist_2 /* SRC 表定义： 创建表 [dbo].[#DataHist]( [ID] [BIGINT] IDENTITY(1,1) 非空， [时间戳] [日期时间] 不为空， [NumericID] [INT] 非空， [BadQ] [BIT] NULL 约束 [DF_DataHist_BadQ] 默认（NULL）， [质量] AS (CASE ISNULL([BadQ],(0)) WHEN (0) THEN (1) ELSE (0) END), [值] VARCHAR 约束 [PK_DataHist] 主键集群 ( [ID] ASC ) )

            --SELECT * FROM [#DataHist]
            CREATE UNIQUE NONCLUSTERED INDEX [IX_DataHist_Time_NumID] ON [dbo].[#DataHist]
            (
                [NumericID] ASC,
                [TimeStamp] ASC
            ) 
            */
            /* Dest table:
            CREATE TABLE [dbo].[#DataHist_2](
            [TimeStamp] [datetime] NOT NULL,
            [NumericID] [int] NOT NULL,
            [Value] [varchar](8000) NULL,
            [BadQ] [bit] NULL CONSTRAINT [DF_DataHist_2_BadQ]  DEFAULT (NULL),
            [Quality]  AS (case isnull([BadQ],(0)) when (0) then (1) else (0) end),
            CONSTRAINT [PK_DataHist_2] PRIMARY KEY CLUSTERED 
            (
               [TimeStamp] ASC,
               [NumericID] ASC
            )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) -- ON [DataHistFG]
            ) -- ON [#DataHistFG]
            */

            BEGIN TRY
            SET XACT_ABORT ON;
            SET NOCOUNT ON;

            PRINT 'copy data from DataHist to DataHist_2';
            PRINT GETUTCDATE();

            DECLARE @nextID BIGINT = 1;
            DECLARE @r INT ,
                @N INT = 1000000;
            DECLARE @s VARCHAR(1000);
            DECLARE @t0 DATETIME;
            SET @r = 1;
            --// find where to re-start copying:
            SET @nextID = ( SELECT TOP ( 1 )
                                    ID
                            FROM    #DataHist DH
                            WHERE   NOT EXISTS ( SELECT 1
                                                 FROM   #DataHist_2 DH2
                                                 WHERE  DH.TimeStamp = DH2.TimeStamp
                                                        AND DH.NumericID = DH2.NumericID )
                            ORDER BY DH.ID
                          );

            PRINT @nextID;
            PRINT GETUTCDATE();
            -- insert in batches of @N:
            WHILE @r > 0
                BEGIN
                    BEGIN TRANSACTION;

                    SET @t0 = GETUTCDATE();

                    INSERT  INTO #DataHist_2
                            ( TimeStamp ,
                              NumericID ,
                              BadQ ,
                              Value
                            ) 
                            SELECT TOP ( @N )
                                    TimeStamp ,
                                    NumericID ,
                                    BadQ ,
                                    Value
                            FROM    #DataHist 
                            WHERE   ID >= @nextID
                            ORDER BY ID 

                    SET @r = @@ROWCOUNT;
                    SELECT @@ROWCOUNT
                    SET @nextID = @nextID + @r;
                    SET @s = 'nextID=' + CAST(@nextID AS VARCHAR(30)) + ', t='
                        + CAST(DATEDIFF(SECOND, @t0, GETUTCDATE()) AS VARCHAR(1000));
                    PRINT @s;

                    COMMIT TRANSACTION;

            END;

            PRINT GETUTCDATE();
            PRINT 'END';

            END TRY
            BEGIN CATCH
            PRINT 'Catch Exception'
            IF @@trancount > 0 
                BEGIN
                    PRINT 'Rolling back transaction.';
                    ROLLBACK TRANSACTION;
                END;
            EXEC usp_GetErrorInfo;
            END CATCH;