Memory optimized Tables and Natively Compiled Stored Procedures

Memory optimized Tables:

SQL Server 2014 support fully durable and delayed duration transaction by default

Memory-optimized tables are fully durable like traditional/existing disk based tables; they support ACID property in case of Default or fully durable setting.

The primary store for memory-optimized tables is main memory and rows in the table are read from and written to memory. The entire table resides in memory. A second copy of the table data is maintained on disk, but only for durability purposes.

For delayed durability see link.

http://dineshbabuverma.blogspot.com/2014/08/delayed-durability-in-sql-server-2014.html

Besides the default durable memory-optimized tables, SQL Server also supports non-durable memory-optimized tables, which are not logged and their data is not persisted on disk. This means that transactions on these tables do not require any disk IO, but the data will not be recovered if there is a server failover.

In memory table rows versioned. Each row has different versions which allow us concurrent reads and writes, Row versions in memory-optimized tables are addressed using 8-byte memory pointers.

 Data in memory-optimized tables is accessed in two ways:

• Through natively compiled SP’s (only support memory optimized tables).
• Through traditional/interpreted SP’s and Ad-hoc queries.

Natively Compiled Stored Procedures:

Natively compiled stored procedures are compiles to native code that access memory-optimized tables and table types only. Allows fast execution of the queries and business logic in it, they get compiled as and when they created, we cannot alter natively compiled sp’s

As they compiled in first creation we comes to know the divide by zero, type conversion and arithmetic over flow errors prior to executions.

Example:

Let us create memory optimized tables and natively compiled SP's

-- DROP DATABASE MyTestingMOT

CREATE DATABASE mytestingmot 

GO

--------------------------------------
-- create database with a memory-optimized filegroup and a container.
-- to add the file  we should have folder DB on drive C
ALTER DATABASE mytestingmot ADD filegroup mytestingmot_filegrp CONTAINS
memory_optimized_data

ALTER DATABASE mytestingmot ADD FILE (name='MyTestingMOT_File1', filename=
'c:\DB\MyTestingMOT_File1') TO filegroup mytestingmot_filegrp

ALTER DATABASE mytestingmot
SET memory_optimized_elevate_to_snapshot=ON
go 

USE MyTestingMOT

go 

-- create a durable (data will be persisted) memory-optimized table
-- two of the columns are indexed  

  CREATE TABLE dbo.moemployee
  (
     moemployeeid   INT NOT NULL PRIMARY KEY NONCLUSTERED,
     moemployeename VARCHAR(100),
     deptid         INT NOT NULL INDEX IX_DeptId NONCLUSTERED HASH WITH (BUCKET_COUNT=10000),
     hiredate       DATETIME2 NOT NULL,
     salary         MONEY
  )WITH (MEMORY_OPTIMIZED=ON)


INSERT dbo.moemployee
VALUES (1,'Allen', 8798, Getdate(), NULL)

INSERT dbo.moemployee
VALUES (2,'Derren', 23, Getdate(), 4445.4)

INSERT dbo.moemployee
VALUES (3,'Sean', 80, Getdate(), NULL)

INSERT dbo.moemployee
VALUES (4,'Alex', 342, Getdate(), 6665.4) GO

-- verify table contents  
   SELECT * FROM   dbo.moemployee 
  GO
 
--  update statistics on memory-optimized tables  
UPDATE STATISTICS dbo.moemployee WITH fullscan, norecompute 
  GO

-- natively compiled stored procedure for to manipulate salary employee salary based on EmpId
-- DROP PROC uspMOEmployee

CREATE PROCEDURE dbo.uspMOEmployee @MOEmployeeId INT,@Salary MONEY
 WITH NATIVE_COMPILATION, SCHEMABINDING, EXECUTE AS OWNER
 AS
 BEGIN ATOMIC
 WITH (TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english')
   
  IF @MOEmployeeId IS NULL
  THROW 51000, N'The MOEmployeeId does not exist.', 1
 
  UPDATE dbo.MOEmployee SET Salary=@Salary WHERE MOEmployeeId=@MOEmployeeId
 END
GO  

/* Unit test Case
Pass paramters @MOEmployeeId and @Salary
EXEC uspMOEmployee @MOEmployeeId= 2, @Salary= 9900  

*/

Execution OutPut:

MOEmployeeId	MOEmployeeName	DeptId	HireDate	Salary
1	Allen	8798	11:51.4	NULL
2	Derren	23	11:51.4	4445.4
3	Sean	80	11:51.4	NULL
4	Alex	342	11:51.4	6665.4

 Note: 

we can not alter Natively compiles sp's, we need to drop and create them. if we try to alter them it shows Error.

Msg 10794, Level 16, State 25, Procedure uspMOEmployee, Line 3
The operation 'ALTER PROCEDURE' is not supported with natively compiled stored procedures.