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内存中OLTP有助于OLTP工作负荷实现显著的性能改进，并减少了处理时间。可以通过将表声明成“内存中优化”来启用内存中OLTP的功能。内存优化表完全支持事务，并且可以使用Transact-SQL进行访问。 Transact-SQL存储过程可以被编译成机器代码从而进一步提升内存优化表的性能。引擎针对高并发进行设计，并使阻塞最小化。
下面的示例(取自MSDN)，展示了如何通过T-SQL创建memory-optimized filegroup、Memory-Optimized Tables，最终可以看到基于磁盘表和内存优化表之间的性能差异，及Native SP带来的进一步性能提升。
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创建数据库，及其内存优化文件组（memory-optimized filegroup）
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CREATE DATABASE imoltp;
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go
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ALTER DATABASE imoltp ADD FILEGROUP [imoltp_mod]
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CONTAINS MEMORY_OPTIMIZED_DATA;
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ALTER DATABASE imoltp ADD FILE
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(name = [imoltp_dir], filename= 'c:\data\imoltp_dir')
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TO FILEGROUP imoltp_mod;
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go
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USE imoltp;
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go
2、创建Memory-OptimizedTables, and NCSProc
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go
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DROP PROCEDURE IF EXISTS ncsp;
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DROP TABLE IF EXISTS sql;
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DROP TABLE IF EXISTS hash_i;
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DROP TABLE IF EXISTS hash_c;
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go
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CREATE TABLE [dbo].[sql] (
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c1 INT NOT NULL PRIMARY KEY,
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c2 NCHAR(48) NOT NULL
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);
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go
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CREATE TABLE [dbo].[hash_i] (
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c1 INT NOT NULL PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT=1000000),
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c2 NCHAR(48) NOT NULL
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) WITH (MEMORY_OPTIMIZED=ON, DURABILITY = SCHEMA_AND_DATA);
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go
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CREATE TABLE [dbo].[hash_c] (
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c1 INT NOT NULL PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT=1000000),
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c2 NCHAR(48) NOT NULL
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) WITH (MEMORY_OPTIMIZED=ON, DURABILITY = SCHEMA_AND_DATA);
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go
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CREATE PROCEDURE ncsp
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@rowcount INT,
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@c NCHAR(48)
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WITH NATIVE_COMPILATION, SCHEMABINDING, EXECUTE AS OWNER
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AS
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BEGIN ATOMIC
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WITH (TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english')
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DECLARE @i INT = 1;
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WHILE @i <= @rowcount
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BEGIN;
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INSERT INTO [dbo].[hash_c] VALUES (@i, @c);
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SET @i += 1;
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END;
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END;
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Go
3、执行下面的T-SQL，可看到内存优化表的性能状况
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go
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SET STATISTICS TIME OFF;
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SET NOCOUNT ON;
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DECLARE @starttime DATETIME2 = sysdatetime();
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DECLARE @timems INT;
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DECLARE @i INT = 1;
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DECLARE @rowcount INT = 1000000;
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DECLARE @c NCHAR(48) = N'12345678901234567890123456789012345678';
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BEGIN TRAN;
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WHILE @i <= @rowcount
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BEGIN;
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INSERT INTO [dbo].[sql] VALUES (@i, @c);
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SET @i += 1;
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END;
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COMMIT;
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SET @timems = datediff(ms, @starttime, sysdatetime());
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SELECT 'A: Disk-based table and interpreted Transact-SQL: '
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+ cast(@timems AS VARCHAR(10)) + ' ms';
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SET @i = 1;
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SET @starttime = sysdatetime();
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BEGIN TRAN;
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WHILE @i <= @rowcount
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BEGIN;
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INSERT INTO [dbo].[hash_i] VALUES (@i, @c);
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SET @i += 1;
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END;
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COMMIT;
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SET @timems = datediff(ms, @starttime, sysdatetime());
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SELECT 'B: memory-optimized table with hash index and interpreted Transact-SQL: '
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+ cast(@timems as VARCHAR(10)) + ' ms';
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SET @starttime = sysdatetime();
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EXECUTE ncsp @rowcount, @c;
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SET @timems = datediff(ms, @starttime, sysdatetime());
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SELECT 'C: memory-optimized table with hash index and native SP:'
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+ cast(@timems as varchar(10)) + ' ms';
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go
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DELETE sql;
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DELETE hash_i;
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DELETE hash_c;
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go
执行结果：
(责任编辑：IT) |
