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Demonstration: Performance Improvement of In-Memory OLTP

  • Raksts

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

The code sample in this topic demonstrates the fast performance of memory-optimized tables. The performance improvement is evident when data in a memory-optimized table is accessed from traditional, interpreted Transact-SQL. This performance improvement is even greater when data in a memory-optimized table is accessed from a natively compiled stored procedure (NCSProc).

To see a more comprehensive demonstration of the potential performance improvements of In-Memory OLTP see In-Memory OLTP Performance Demo v1.0.

The code example in the present article is single-threaded, and it doesn't take advantage of the concurrency benefits of In-Memory OLTP. A workload that uses concurrency will see a greater performance gain. The code example shows only one aspect of performance improvement, namely data access efficiency for INSERT.

The performance improvement offered by memory-optimized tables is fully realized when data in a memory-optimized table is accessed from a NCSProc.

Code Example

The following subsections describe each step.

Step 1a: Prerequisite If Using SQL Server

The steps in this first subsection apply only if you're running in SQL Server, and doesn't apply if you're running in Azure SQL Database. Do the following:

  1. Use SQL Server Management Studio (SSMS.exe) to connect to your SQL Server. Or any tool similar to SSMS.exe is fine.

  2. Manually create a directory named C:\data\. The sample Transact-SQL code expects the directory to pre-exist.

  3. Run the short T-SQL to create the database and its memory-optimized filegroup.

go  
CREATE DATABASE imoltp;    --  Transact-SQL  
go  
  
ALTER DATABASE imoltp ADD FILEGROUP [imoltp_mod]  
    CONTAINS MEMORY_OPTIMIZED_DATA;  
  
ALTER DATABASE imoltp ADD FILE  
    (name = [imoltp_dir], filename= 'c:\data\imoltp_dir')  
    TO FILEGROUP imoltp_mod;  
go  
  
USE imoltp;  
go

Step 1b: Prerequisite If Using Azure SQL Database

This subsection applies only if you're using Azure SQL Database. Do the following:

  1. Decide which existing test database you'll use for the code example.

  2. If you decide to create a new test database, use the Azure portal to create a database named imoltp.

If you would like instructions for using the Azure portal for this, see Get Started with Azure SQL Database.

Step 2: Create Memory-Optimized Tables, and NCSProc

This step creates memory-optimized tables, and a natively compiled stored procedure (NCSProc). Do the following:

  1. Use SSMS.exe to connect to your new database.

  2. Run the following T-SQL in your database.

go  
DROP PROCEDURE IF EXISTS ncsp;  
DROP TABLE IF EXISTS sql;  
DROP TABLE IF EXISTS hash_i;  
DROP TABLE IF EXISTS hash_c;  
go  
  
CREATE TABLE [dbo].[sql] (  
  c1 INT NOT NULL PRIMARY KEY,  
  c2 NCHAR(48) NOT NULL  
);  
go  
  
CREATE TABLE [dbo].[hash_i] (  
  c1 INT NOT NULL PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT=1000000),  
  c2 NCHAR(48) NOT NULL  
) WITH (MEMORY_OPTIMIZED=ON, DURABILITY = SCHEMA_AND_DATA);  
go  
  
CREATE TABLE [dbo].[hash_c] (  
  c1 INT NOT NULL PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT=1000000),  
  c2 NCHAR(48) NOT NULL  
) WITH (MEMORY_OPTIMIZED=ON, DURABILITY = SCHEMA_AND_DATA);  
go  
  
CREATE PROCEDURE ncsp  
    @rowcount INT,  
    @c NCHAR(48)  
  WITH NATIVE_COMPILATION, SCHEMABINDING, EXECUTE AS OWNER  
  AS   
  BEGIN ATOMIC   
  WITH (TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english')  
  DECLARE @i INT = 1;  
  WHILE @i <= @rowcount  
  BEGIN;  
    INSERT INTO [dbo].[hash_c] VALUES (@i, @c);  
    SET @i += 1;  
  END;  
END;  
go

Step 3: Run the Code

Now you can execute the queries that will demonstrate the performance of memory-optimized tables. Do the following:

  1. Use SSMS.exe to run the following T-SQL in your database.

    Ignore any speed or other performance data this first run generates. The first run ensure several one-time only operations are performed, such as initial allocations of memory.

  2. Again, use SSMS.exe to rerun the following T-SQL in your database.

go  
SET STATISTICS TIME OFF;  
SET NOCOUNT ON;  
  
-- Inserts, one at a time.  
  
DECLARE @starttime DATETIME2 = sysdatetime();  
DECLARE @timems INT;  
DECLARE @i INT = 1;  
DECLARE @rowcount INT = 100000;  
DECLARE @c NCHAR(48) = N'12345678901234567890123456789012345678';  
  
-- Harddrive-based table and interpreted Transact-SQL.  
  
BEGIN TRAN;  
  WHILE @i <= @rowcount  
  BEGIN;  
    INSERT INTO [dbo].[sql] VALUES (@i, @c);  
    SET @i += 1;  
  END;  
COMMIT;  
  
SET @timems = datediff(ms, @starttime, sysdatetime());  
SELECT 'A: Disk-based table and interpreted Transact-SQL: '  
    + cast(@timems AS VARCHAR(10)) + ' ms';  
  
-- Interop Hash.  
  
SET @i = 1;  
SET @starttime = sysdatetime();  
  
BEGIN TRAN;  
  WHILE @i <= @rowcount  
    BEGIN;  
      INSERT INTO [dbo].[hash_i] VALUES (@i, @c);  
      SET @i += 1;  
    END;  
COMMIT;  
  
SET @timems = datediff(ms, @starttime, sysdatetime());  
SELECT 'B: memory-optimized table with hash index and interpreted Transact-SQL: '  
    + cast(@timems as VARCHAR(10)) + ' ms';  
  
-- Compiled Hash.  
  
SET @starttime = sysdatetime();  
  
EXECUTE ncsp @rowcount, @c;  
  
SET @timems = datediff(ms, @starttime, sysdatetime());  
SELECT 'C: memory-optimized table with hash index and native SP:'  
    + cast(@timems as varchar(10)) + ' ms';  
go  
  
DELETE sql;  
DELETE hash_i;  
DELETE hash_c;  
go

Next are the output time statistics generated by our second test run.

10453 ms , A: Disk-based table and interpreted Transact-SQL.  
5626 ms , B: memory-optimized table with hash index and interpreted Transact-SQL.  
3937 ms , C: memory-optimized table with hash index and native SP.

See Also

In-Memory OLTP (In-Memory Optimization)