SQL中的最小记录条件

9

我已经写了一个脚本来测试此页面上的声明http://technet.microsoft.com/zh-cn/library/dd425070(v=sql.100).aspx，其标题为“何时汇总最小记录条件”最小记录不会或不会发生。

使用此脚本，我发现每种不同类型的插入的日志记录长度的总和如下：

  • 堆空没有Tablock 60000
  • 带有锁的堆空​​56000
  • 堆非空无制表符60000
  • 非空堆，带锁56000
  • 堆加索引为空，没有制表符126188
  • 堆加索引为空，带挂锁114188
  • 堆加索引非空无选项卡锁138696
  • 带有Tablock的堆加索引不为空112000
  • 集群为空命令无制表符64168
  • 集群空，带tablock 56168命令
  • 群集为空无序无标签锁73388
  • 空群集，无序，带有tablock 65388
  • 群集非空无标签锁63912
  • 带锁的群集非空55944
  • 群集加索引为空，没有制表符124336
  • 带有Tablock的簇加索引为空108336
  • 群集加索引非空无选项卡锁123876
  • 带Tablock的群集加索引不为空107924

其中一些数字似乎与technet页面上的表不匹配。特别是：

  • 插入到空表和非空表之间的日志记录似乎没有什么区别，但是该页面声称，插入到没有制表符的非空集群中时，应该有完整的日志记录
  • 使用tablock插入具有and index的堆或群集似乎确实减少了日志记录，但是该页面声称应该有完整的日志记录。
  • 使用insert的SELECT INTO方法时，fn_dblog中没有要插入其操作的行，但是该页将该方法列为应具有表中所述行为的批量加载操作。

作为参考，它在SQL Express数据库上运行，当我运行DBCC TRACESTATUS（610）时，所有内容均为0。

谁能帮助解释为什么我会看到这些差异？

供参考，代码如下： 

SET NOCOUNT ON

CREATE TABLE numbers (num INT)
CREATE TABLE numbersUnordered (num INT)

Declare @cnt int
Select @cnt=0
while (@cnt<500)
BEGIN
INSERT INTO NUMBERS(num) SELECT @cnt
SELECT @cnt=@cnt+1
END

Select @cnt=0
while (@cnt<250)
BEGIN
INSERT INTO numbersUnordered(num) SELECT @cnt*2
SELECT @cnt=@cnt+1
END

Select @cnt=0
while (@cnt<250)
BEGIN
INSERT INTO numbersUnordered(num) SELECT @cnt*2+1
SELECT @cnt=@cnt+1
END


---- heap empty without tablock
CREATE TABLE noKey1 (val INT)

INSERT INTO noKey1 (val)
SELECT * FROM numbers

DECLARE @heapEmptyNoTablock INT

SELECT @heapEmptyNoTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey1%'
AND operation like '%insert%'

---- heap empty with tablock
CREATE TABLE noKey2 (val INT)

INSERT INTO noKey2 WITH(TABLOCK) (val)
SELECT * FROM numbers

DECLARE @heapEmptyTablock INT

SELECT @heapEmptyTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey2%'
AND operation like '%insert%'

---- heap non empty without tablock
CREATE TABLE noKey3 (val INT)

INSERT INTO noKey3 WITH(TABLOCK) (val)
SELECT * FROM numbers

INSERT INTO noKey3 (val)
SELECT num+5 FROM numbers

DECLARE @heapNonEmptyNoTablock INT

SELECT @heapNonEmptyNoTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 500 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey3%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

---- heap non empty with tablock
CREATE TABLE noKey4 (val INT)

INSERT INTO noKey4 WITH(TABLOCK) (val)
SELECT * FROM numbers

INSERT INTO noKey4 WITH (TABLOCK) (val)
SELECT num+5 FROM numbers

DECLARE @heapNonEmptyTablock INT

SELECT @heapNonEmptyTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 500 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey4%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- heap plus index empty without tablock
CREATE TABLE noKey5 (val INT)
CREATE INDEX MSindex1
ON noKey5 (val)

INSERT INTO noKey5 (val)
SELECT * FROM numbers

DECLARE @heapIndexEmptyNoTablock INT

SELECT @heapIndexEmptyNoTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey5%'
AND operation like '%insert%'


--- heap plus index empty with tablock
CREATE TABLE noKey6 (val INT)
CREATE INDEX MSindex2
ON noKey6 (val)

INSERT INTO noKey6 WITH(TABLOCK) (val)
SELECT * FROM numbers

DECLARE @heapIndexEmptyTablock INT

SELECT @heapIndexEmptyTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey6%'
AND operation like '%insert%'

--- heap plus index non empty without tablock
CREATE TABLE noKey7 (val INT)
CREATE INDEX MSindex3
ON noKey7 (val)

INSERT INTO noKey7 WITH(TABLOCK) (val)
SELECT * FROM numbers

INSERT INTO noKey7 (val)
SELECT num+5 FROM numbers

DECLARE @heapIndexNonEmptyNoTablock INT

SELECT @heapIndexNonEmptyNoTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 1000 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey7%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- heap plus index non empty with tablock
CREATE TABLE noKey8 (val INT)
CREATE INDEX MSindex4
ON noKey7 (val)

INSERT INTO noKey8 WITH(TABLOCK) (val)
SELECT * FROM numbers

INSERT INTO noKey8 WITH(TABLOCK) (val)
SELECT num+5 FROM numbers

DECLARE @heapIndexNonEmptyTablock INT

SELECT @heapIndexNonEmptyTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 1000 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%noKey8%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- cluster empty ordered without tablock
CREATE TABLE withKey1 (val INT PRIMARY KEY)

INSERT INTO withKey1 (val)
SELECT * FROM numbers

DECLARE @clusterEmptyNoTablock INT

SELECT @clusterEmptyNoTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey1%'
AND operation like '%insert%'

--- cluster empty ordered with tablock
CREATE TABLE withKey2 (val INT PRIMARY KEY)

INSERT INTO withKey2 WITH(TABLOCK) (val)
SELECT * FROM numbers

DECLARE @clusterEmptyTablock INT

SELECT @clusterEmptyTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey2%'
AND operation like '%insert%'

--- cluster empty unordered without tablock
CREATE TABLE withKey5 (val INT PRIMARY KEY)

INSERT INTO withKey5 (val)
SELECT * FROM numbersUnordered

DECLARE @clusterEmptyNoTablockUnordered INT

SELECT @clusterEmptyNoTablockUnordered = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey5%'
AND operation like '%insert%'

--- cluster empty undordered with tablock
CREATE TABLE withKey6 (val INT PRIMARY KEY)

INSERT INTO withKey6 WITH(TABLOCK) (val)
SELECT * FROM numbersUnordered

DECLARE @clusterEmptyTablockUnordered INT

SELECT @clusterEmptyTablockUnordered = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey6%'
AND operation like '%insert%'

--- cluster non empty no tablock
CREATE TABLE withKey7 (val INT PRIMARY KEY)

INSERT INTO withKey7 (val)
SELECT num FROM numbers

INSERT INTO withKey7 (val)
SELECT num+500 FROM numbers

DECLARE @clusterNonEmptyNoTablock INT

SELECT @clusterNonEmptyNoTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 500 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey7%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- cluster non empty with tablock
CREATE TABLE withKey8 (val INT PRIMARY KEY)

INSERT INTO withKey8 WITH(TABLOCK) (val)
SELECT num FROM numbers

INSERT INTO withKey8 WITH(TABLOCK) (val)
SELECT num+500 FROM numbers

DECLARE @clusterNonEmptyTablock INT

SELECT @clusterNonEmptyTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 500 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey8%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- cluster plus index empty no tablock
CREATE TABLE withKey9 (val INT PRIMARY KEY)
CREATE INDEX MSindex5
ON withKey9 (val)

INSERT INTO withKey9 (val)
SELECT * FROM numbers

DECLARE @clusterIndexEmptyNoTablock INT

SELECT @clusterIndexEmptyNoTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey9%'
AND operation like '%insert%'

--- cluster plus index empty with tablock
CREATE TABLE withKey10 (val INT PRIMARY KEY)
CREATE INDEX MSindex6
ON withKey10 (val)

INSERT INTO withKey10 WITH(TABLOCK) (val)
SELECT * FROM numbers

DECLARE @clusterIndexEmptyTablock INT

SELECT @clusterIndexEmptyTablock = SUM([Log Record Length])
FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey10%'
AND operation like '%insert%'

--- cluster plus index nonempty no tablock
CREATE TABLE withKey11 (val INT PRIMARY KEY)
CREATE INDEX MSindex7
ON withKey11 (val)

INSERT INTO withKey11 (val)
SELECT num FROM numbers

INSERT INTO withKey11 (val)
SELECT num+500 FROM numbers

DECLARE @clusterIndexNonEmptyNoTablock INT

SELECT @clusterIndexNonEmptyNoTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 1000 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey11%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- cluster plus index nonempty with tablock
CREATE TABLE withKey12 (val INT PRIMARY KEY)
CREATE INDEX MSindex8
ON withKey12 (val)

INSERT INTO withKey12 WITH(TABLOCK) (val)
SELECT num FROM numbers

INSERT INTO withKey12 WITH(TABLOCK) (val)
SELECT num+500 FROM numbers

DECLARE @clusterIndexNonEmptyTablock INT

SELECT @clusterIndexNonEmptyTablock = SUM(a.[Log Record Length])
FROM 
(SELECT TOP 1000 * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%withKey12%'
AND operation like '%insert%'
ORDER BY [Current LSN] desc) a

--- select into
/*SELECT * 
INTO selectIntoTable
FROM numbers

SELECT * FROM sys.fn_dblog(null, null)
WHERE allocunitname like '%selectIntoTable%'
AND operation like '%insert%'

DROP TABLE selectIntoTable
*/


PRINT 'Heap empty no tablock ' + CAST(@heapEmptyNoTablock AS VARCHAR)
PRINT 'Heap empty with tablock ' + CAST(@heapEmptyTablock AS VARCHAR)
PRINT 'Heap non empty no tablock ' + CAST(@heapNonEmptyNoTablock AS VARCHAR)
PRINT 'Heap non empty with tablock ' + CAST(@heapNonEmptyTablock AS VARCHAR)
PRINT 'Heap plus index empty no tablock ' + CAST(@heapIndexEmptyNoTablock AS VARCHAR)
PRINT 'Heap plus index empty with tablock ' + CAST(@heapIndexEmptyTablock AS VARCHAR)
PRINT 'Heap plus index non empty no tablock ' + CAST(@heapIndexNonEmptyNoTablock AS VARCHAR)
PRINT 'Heap plus index non empty with tablock ' + CAST(@heapIndexNonEmptyTablock AS VARCHAR)
PRINT 'Cluster empty ordered no tablock ' + CAST(@clusterEmptyNoTablock AS VARCHAR)
PRINT 'Cluster empty ordered with tablock ' + CAST(@clusterEmptyTablock AS VARCHAR)
PRINT 'Cluster empty unordered no tablock ' + CAST(@clusterEmptyNoTablockUnordered AS VARCHAR)
PRINT 'Cluster empty unordered with tablock ' + CAST(@clusterEmptyTablockUnordered AS VARCHAR)
PRINT 'Cluster non empty no tablock ' + CAST(@clusterNonEmptyNoTablock AS VARCHAR)
PRINT 'Cluster non empty with tablock ' + CAST(@clusterNonEmptyTablock AS VARCHAR)
PRINT 'Cluster plus index empty no tablock ' + CAST(@clusterIndexEmptyNoTablock AS VARCHAR)
PRINT 'Cluster plus index empty with tablock ' + CAST(@clusterIndexEmptyTablock AS VARCHAR)
PRINT 'Cluster plus index non empty no tablock ' + CAST(@clusterIndexNonEmptyNoTablock AS VARCHAR)
PRINT 'Cluster plus index non empty with tablock ' + CAST(@clusterIndexNonEmptyTablock AS VARCHAR)


DROP TABLE numbers
DROP TABLE numbersUnordered
DROP TABLE noKey1
DROP TABLE noKey2
DROP TABLE noKey3
DROP TABLE noKey4
DROP TABLE noKey5
DROP TABLE noKey6
DROP TABLE noKey7
DROP TABLE noKey8
DROP TABLE withKey1
DROP TABLE withKey2
DROP TABLE withKey5
DROP TABLE withKey6
DROP TABLE withKey7
DROP TABLE withKey8
DROP TABLE withKey9
DROP TABLE withKey10
DROP TABLE withKey11
DROP TABLE withKey12
sql-server  sql-server-2008  bulk-insert 

Answers:

12

其中一些数字似乎与technet页面上的表不匹配。

在测试中生成的日志记录的大小存在细微的差异，但这是由于其他内部日志记录行为所致，而不是是否正在进行最少的日志记录。

Storage Engine团队的Sunil Agarwal提供了对最小日志记录的良好定义：

不记录单个行，仅记录对页面分配结构的更改

您看到记录了各个行更改的任何测试（例如LOP_INSERT_ROWS）都没有为关联的分配单元使用最少的记录。某些操作可以相对于一个分配单位（例如索引）进行最小记录，而不能针对另一个分配单元进行最小记录。同样，在某些情况下，对现有页面的插入可能不会被最少记录，但是对新分配的页面的更改可能会被记录。

大多数细节可以在一系列存储引擎团队博客文章中找到：

没有探索的一个细节是，要以最少的日志记录（在SQL Server 2008或更高版本中），INSERT...SELECT对b树结构的更改必须将DMLRequestSort查询计划操作符属性设置为true。这适用于《数据加载性能指南》显示“取决于”的情况：查询计划必须对进行广泛（按索引）维护DMLRequestSort=true。

我在使用INSERT…SELECT和快速加载上下文进行最小日志记录中写了更多有关此的内容。

— 保罗·怀特9
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