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锁 -分区锁（新特点）

SQL SERVER 数据库提供的锁有以下几种：

1、行锁

2、页锁

3、表锁

4、数据库锁

5、分区锁 （SQL SERVER 2008新特点）

/**********************************************************
Author="WZ"
Create Date="2009/9/6"
SQL SERVER 2008开发系列（三）锁- 分区锁（新特点）
**********************************************************/

Use Master
Go
--创建演示数据库
IF EXISTS (SELECT name FROM sys.databases WHERE name = N'LockEscalationTest')
DROP DATABASE LockEscalationTest
GO

Create Database LockEscalationTest
on
(
NAME = LockEscalationTest_dat,
FileName = 'D:\数据库\SQL2008\LockEscalationTest_dat.mdf',
Size = 10MB,
Maxsize = 100MB,
FileGrowth = 5MB
)
LOG ON
(
Name = LockEscalationTest_Log,
FileName = 'D:\数据库\SQL2008\LockEscalationTest_log.ldf',
Size = 5MB,
MaxSize = 25MB,
FileGrowth = 5MB
)
Go

USE LockEscalationTest;
GO

-- 创建三个分区: -7999, 8000-15999, 16000+
CREATE PARTITION FUNCTION MyPartitionFunction (INT) AS RANGE RIGHT FOR VALUES (8000, 16000);
GO

CREATE PARTITION SCHEME MyPartitionScheme AS PARTITION MyPartitionFunction
ALL TO ([PRIMARY]);
GO

-- 创建分区表
CREATE TABLE MyPartitionedTable (c1 INT);
GO

CREATE CLUSTERED INDEX MPT_Clust ON MyPartitionedTable (c1)
ON MyPartitionScheme (c1);
GO

-- 填充表
SET NOCOUNT ON;
GO

DECLARE @a INT = 1;
WHILE (@a < 17000)
BEGIN
INSERT INTO MyPartitionedTable VALUES (@a);
SELECT @a = @a + 1;
END;
GO
--查询数据表
select * from MyPartitionedTable

--设置锁的升级策略为Table
ALTER TABLE MyPartitionedTable SET (LOCK_ESCALATION = TABLE);
GO

--开始一个更新数据的事务
BEGIN TRAN
UPDATE MyPartitionedTable SET c1 = c1 WHERE c1 < 7500;
GO

--查询锁的分配情况
SELECT [resource_type], [resource_associated_entity_id], [request_mode],
[request_type], [request_status] FROM sys.dm_tran_locks WHERE [resource_type] <> 'DATABASE';
GO

--回滚事务
ROLLBACK TRAN;
GO

--连接1
--设置锁的升级策略为AUTO(即启用分区级别的锁)
ALTER TABLE MyPartitionedTable SET (LOCK_ESCALATION = AUTO);
GO

--开始一个更新数据的事务
BEGIN TRAN
UPDATE MyPartitionedTable SET c1 = c1 WHERE c1 < 7500;
GO

--查询锁的分配情况
SELECT [partition_id], [object_id], [index_id], [partition_number]
FROM sys.partitions WHERE object_id = OBJECT_ID ('MyPartitionedTable');
GO

SELECT [resource_type], [resource_associated_entity_id], [request_mode],
[request_type], [request_status] FROM sys.dm_tran_locks WHERE [resource_type] <> 'DATABASE';
GO

--连接2
USE LockEscalationTest;
GO

BEGIN TRAN
UPDATE MyPartitionedTable set c1 = c1 WHERE c1 > 8100 AND c1 < 15900;
GO

SELECT [partition_id], [object_id], [index_id], [partition_number]
FROM sys.partitions WHERE object_id = OBJECT_ID ('MyPartitionedTable');
GO

SELECT [resource_type], [resource_associated_entity_id], [request_mode],
[request_type], [request_status] FROM sys.dm_tran_locks WHERE [resource_type] <> 'DATABASE';

--通过以上查询，我们可以查看表分区被锁情况，如下图所示：

GO

--连接1
SELECT * FROM MyPartitionedTable WHERE c1 = 8500;
GO

--连接2
SELECT * FROM MyPartitionedTable WHERE c1 = 100;
GO