在聚簇索引上使用顺序GUID键的INSERT不会明显更快

Question

在SQL Server 2008中，我尝试重现来自顺序索引和非顺序GUID密钥的聚集索引的实验结果，此处的
http://sqlblog.com/blogs/denis_gobo/archive/2009/02/05/11743。
aspx，

但我并没有体验到我期望的（和作者所体验到的）插入速度的显着提高。顺序GUID明显提高了页面利用率，但是由于某些原因，插入10,000行仅快100毫秒左右（10,300毫秒中）。

我使用以下代码：

CREATE TABLE TestGuid1 (Id UNIQUEIDENTIFIER not null DEFAULT newid(),
SomeDate DATETIME, batchNumber BIGINT)

CREATE TABLE TestGuid2 (Id UNIQUEIDENTIFIER not null DEFAULT newsequentialid(),
SomeDate DATETIME, batchNumber BIGINT)

CREATE CLUSTERED INDEX ix_id1 ON TestGuid1(id)
CREATE CLUSTERED INDEX ix_id2 ON TestGuid2(id)

go

SET NOCOUNT ON
INSERT TestGuid1 (SomeDate,batchNumber) VALUES (GETDATE(),3)
go 10000

SET NOCOUNT ON
INSERT TestGuid2 (SomeDate,batchNumber) VALUES (GETDATE(),3)
go 10000

DBCC showcontig ('TestGuid1') WITH tableresults
DBCC showcontig ('TestGuid2')  WITH tableresults

SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate))
FROM TestGuid1
GROUP BY batchNumber

SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate))
FROM TestGuid2
GROUP BY batchNumber

谁能解释为什么我在TestGuid2上没有更快的插入速度？

后续 ： 按照
下面线程中的要求，我扩大了测试范围：测试结果倾向于随时间变化很大，因此现在将实验重复N次，并报告总和平均使用时间。我还添加了第三项测试，即针对顺序整数列上的主键。这应该是这三种方法中最快，最紧凑的，因为整数类型较小并且IDENTITY（1,1）快（或至少应该快）。至少根据我的直觉。现在，
平均 执行时间有益于顺序GUID，但是令人惊讶的是，在第三个实验中（使用顺序整数键）插入的 速度 比顺序GUID 慢
。我对此没有任何解释。这是新实验的代码：

SET NOCOUNT ON

CREATE TABLE TestGuid1 (Id UNIQUEIDENTIFIER NOT NULL DEFAULT NEWID() PRIMARY KEY,
SomeDate DATETIME, batchNumber BIGINT, FILLER CHAR(100))

CREATE TABLE TestGuid2 (Id UNIQUEIDENTIFIER NOT NULL DEFAULT NEWSEQUENTIALID() PRIMARY KEY,
SomeDate DATETIME, batchNumber BIGINT, FILLER CHAR(100))

CREATE TABLE TestInt (Id Int NOT NULL identity(1,1) PRIMARY KEY,
SomeDate DATETIME, batchNumber BIGINT, FILLER CHAR(100))

DECLARE @BatchCounter INT = 1
DECLARE @Numrows INT = 100000


WHILE (@BatchCounter <= 20)
BEGIN 
BEGIN TRAN

DECLARE @LocalCounter INT = 0

    WHILE (@LocalCounter <= @NumRows)
    BEGIN
    INSERT TestGuid1 (SomeDate,batchNumber) VALUES (GETDATE(),@BatchCounter)
    SET @LocalCounter +=1
    END

SET @LocalCounter = 0

    WHILE (@LocalCounter <= @NumRows)
    BEGIN
    INSERT TestGuid2 (SomeDate,batchNumber) VALUES (GETDATE(),@BatchCounter)
    SET @LocalCounter +=1
    END

SET @LocalCounter = 0

    WHILE (@LocalCounter <= @NumRows)
    BEGIN
    INSERT TestInt (SomeDate,batchNumber) VALUES (GETDATE(),@BatchCounter)
    SET @LocalCounter +=1
    END

SET @BatchCounter +=1
COMMIT 
END

DBCC showcontig ('TestGuid1') WITH tableresults
DBCC showcontig ('TestGuid2')  WITH tableresults
DBCC showcontig ('TestInt')  WITH tableresults

SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate)) AS [NEWID()]
FROM TestGuid1
GROUP BY batchNumber

SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate)) AS [NEWSEQUENTIALID()]
FROM TestGuid2
GROUP BY batchNumber

SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate)) AS [IDENTITY()]
FROM TestInt
GROUP BY batchNumber

DROP TABLE TestGuid1
DROP TABLE TestGuid2
DROP TABLE TestInt

而 平均 执行时间：

NEWID()            3064
NEWSEQUENTIALID()  1977
IDENTITY()         2223

页面用法如下：

Table          Pages  AveragePageDensity
----------------------------------------
TestGuid1      50871  68,4
TestGuid2      35089  99,2
TestInt        32259  98,7

我看不到，为什么这些网页统计信息（最适合TestInt）并不意味着实验3最快。

Answer 1

您可以尝试修改后的脚本并发布结果吗？

    SET NOCOUNT ON

    CREATE TABLE TestGuid1 (Id UNIQUEIDENTIFIER NOT NULL DEFAULT NEWID() PRIMARY KEY,
    SomeDate DATETIME, batchNumber BIGINT, FILLER CHAR(100))

    CREATE TABLE TestGuid2 (Id UNIQUEIDENTIFIER NOT NULL DEFAULT NEWSEQUENTIALID() PRIMARY KEY,
    SomeDate DATETIME, batchNumber BIGINT, FILLER CHAR(100))

    DECLARE @BatchCounter INT = 1

    WHILE (@BatchCounter <= 20)
    BEGIN 
    BEGIN TRAN

    DECLARE @LocalCounter INT = 0

        WHILE (@LocalCounter <= 100000)
        BEGIN
        INSERT TestGuid1 (SomeDate,batchNumber) VALUES (GETDATE(),@BatchCounter)
        SET @LocalCounter +=1
        END

    SET @LocalCounter = 0

        WHILE (@LocalCounter <= 100000)
        BEGIN
        INSERT TestGuid2 (SomeDate,batchNumber) VALUES (GETDATE(),@BatchCounter)
        SET @LocalCounter +=1
        END

    SET @BatchCounter +=1
    COMMIT 
    END

    DBCC showcontig ('TestGuid1') WITH tableresults
    DBCC showcontig ('TestGuid2')  WITH tableresults

    SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate)) AS [NEWID()]
    FROM TestGuid1
    GROUP BY batchNumber

    SELECT batchNumber,DATEDIFF(ms,MIN(SomeDate),MAX(SomeDate)) AS [NEWSEQUENTIALID()]
    FROM TestGuid2
    GROUP BY batchNumber

DROP TABLE TestGuid1
DROP TABLE TestGuid2

我发现各个运行之间的结果差异很大（在我的笔记本电脑上而不是服务器上！），但是连续运行的明显趋势是更快。

NEWID() 均值5168.9

batchNumber          NEWID()
-------------------- -----------
1                    4270
2                    2480
3                    2706
4                    3333
5                    7480
6                    5346
7                    4306
8                    7713
9                    7313
10                   4760
11                   4680
12                   4113
13                   3433
14                   2686
15                   4963
16                   8040
17                   5313
18                   8160
19                   9533
20                   2750

NEWSEQUENTIALID() 均值3000.85

batchNumber          NEWSEQUENTIALID()
-------------------- -----------------
1                    2016
2                    1820
3                    1886
4                    1870
5                    4873
6                    3473
7                    3730
8                    3690
9                    1983
10                   2020
11                   1906
12                   5596
13                   2100
14                   1950
15                   2096
16                   1876
17                   5196
18                   2110
19                   2113
20                   7713