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Walkthrough for the performance features of SQL Server on Linux

  • Artikkeli

Applies to: SQL Server - Linux

If you're a Linux user who is new to SQL Server, the following tasks walk you through some of the performance features. These aren't unique or specific to Linux, but it helps to give you an idea of areas to investigate further. In each example, a link is provided to the depth documentation for that area.

Note

The following examples use the AdventureWorks2022 sample database. For instructions on how to obtain and install this sample database, see Migrate a SQL Server database from Windows to Linux using backup and restore.

Create a columnstore index

A columnstore index is a technology for storing and querying large stores of data in a columnar data format, called a columnstore.

  1. Add a columnstore index to the SalesOrderDetail table by executing the following Transact-SQL commands:

    CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_SalesOrderDetail_ColumnStore]
    ON Sales.SalesOrderDetail(UnitPrice, OrderQty, ProductID);
GO

  2. Execute the following query that uses the columnstore index to scan the table:

    SELECT ProductID,
       SUM(UnitPrice) AS SumUnitPrice,
       AVG(UnitPrice) AS AvgUnitPrice,
       SUM(OrderQty) AS SumOrderQty,
       AVG(OrderQty) AS AvgOrderQty
FROM Sales.SalesOrderDetail
GROUP BY ProductID
ORDER BY ProductID;

  3. Verify that the columnstore index was used by looking up the object_id for the columnstore index and confirming that it appears in the usage stats for the SalesOrderDetail table:

    SELECT *
FROM sys.indexes
WHERE name = 'IX_SalesOrderDetail_ColumnStore';
GO

SELECT *
FROM sys.dm_db_index_usage_stats
WHERE database_id = DB_ID('AdventureWorks2022')
      AND object_id = OBJECT_ID('AdventureWorks2022.Sales.SalesOrderDetail');

Use In-Memory OLTP

SQL Server provides In-Memory OLTP features that can greatly improve the performance of application systems. This section walks you through the steps to create a memory-optimized table stored in memory and a natively compiled stored procedure that can access the table without needing to be compiled or interpreted.

Configure Database for In-Memory OLTP

  1. You should set the database to a compatibility level of at least 130 to use In-Memory OLTP. Use the following query to check the current compatibility level of AdventureWorks2022:

    USE AdventureWorks2022;
GO

SELECT d.compatibility_level
FROM sys.databases AS d
WHERE d.name = DB_NAME();
GO

    If necessary, update the level to 130:

    ALTER DATABASE CURRENT
    SET COMPATIBILITY_LEVEL = 130;
GO

  2. When a transaction involves both a disk-based table and a memory-optimized table, it's essential that the memory-optimized portion of the transaction operates at the transaction isolation level named SNAPSHOT. To reliably enforce this level for memory-optimized tables in a cross-container transaction, execute the following:

    ALTER DATABASE CURRENT
    SET MEMORY_OPTIMIZED_ELEVATE_TO_SNAPSHOT = ON;
GO

  3. Before you can create a memory-optimized table, you must first create a memory optimized filegroup, and a container for data files:

    ALTER DATABASE AdventureWorks2022
    ADD FILEGROUP AdventureWorks_mod CONTAINS MEMORY_OPTIMIZED_DATA;
GO

ALTER DATABASE AdventureWorks2022
    ADD FILE (NAME = 'AdventureWorks_mod', FILENAME = '/var/opt/mssql/data/AdventureWorks_mod') TO FILEGROUP AdventureWorks_mod;
GO

Create a memory-optimized table

The primary store for memory-optimized tables is main memory and so unlike disk-based tables, data doesn't need to be read in from disk into memory buffers. To create a memory-optimized table, use the MEMORY_OPTIMIZED = ON clause.

  1. Execute the following query to create the memory-optimized table dbo.ShoppingCart. As a default, the data is persisted on disk for durability purposes (DURABILITY can also be set to persist the schema only).

    CREATE TABLE dbo.ShoppingCart
(
    ShoppingCartId INT IDENTITY (1, 1) PRIMARY KEY NONCLUSTERED,
    UserId INT NOT NULL INDEX ix_UserId NONCLUSTERED HASH WITH (BUCKET_COUNT = 1000000),
    CreatedDate DATETIME2 NOT NULL,
    TotalPrice MONEY
)
WITH (MEMORY_OPTIMIZED = ON);
GO

  2. Insert some records into the table:

    INSERT dbo.ShoppingCart
VALUES (8798, SYSDATETIME(), NULL);

INSERT dbo.ShoppingCart
VALUES (23, SYSDATETIME(), 45.4);

INSERT dbo.ShoppingCart
VALUES (80, SYSDATETIME(), NULL);

INSERT dbo.ShoppingCart
VALUES (342, SYSDATETIME(), 65.4);

Natively compiled stored procedures

SQL Server supports natively compiled stored procedures that access memory-optimized tables. The T-SQL statements are compiled to machine code and stored as native DLLs, enabling faster data access and more efficient query execution than traditional T-SQL. Stored procedures that are marked with NATIVE_COMPILATION are natively compiled.

  1. Execute the following script to create a natively compiled stored procedure that inserts a large number of records into the ShoppingCart table:

    CREATE PROCEDURE dbo.usp_InsertSampleCarts
@InsertCount INT
WITH NATIVE_COMPILATION, SCHEMABINDING
AS
BEGIN ATOMIC
WITH (TRANSACTION ISOLATION LEVEL = SNAPSHOT, LANGUAGE = N'us_english')
    DECLARE @i AS INT = 0;
    WHILE @i < @InsertCount
        BEGIN
            INSERT INTO dbo.ShoppingCart
            VALUES (1, SYSDATETIME(), NULL);
            SET @i += 1;
        END
END;

  2. Insert 1,000,000 rows:

    EXECUTE usp_InsertSampleCarts 1000000;

  3. Verify the rows have been inserted:

    SELECT COUNT(*)
FROM dbo.ShoppingCart;

Use Query Store

Query Store collects detailed performance information about queries, execution plans, and runtime statistics.

Before SQL Server 2022 (16.x), Query Store isn't enabled by default, and can be enabled with ALTER DATABASE:

ALTER DATABASE AdventureWorks2022
    SET QUERY_STORE = ON;

Run the following query to return information about queries and plans in the Query Store:

SELECT Txt.query_text_id,
       Txt.query_sql_text,
       Pl.plan_id,
       Qry.*
FROM sys.query_store_plan AS Pl
     INNER JOIN sys.query_store_query AS Qry
         ON Pl.query_id = Qry.query_id
     INNER JOIN sys.query_store_query_text AS Txt
         ON Qry.query_text_id = Txt.query_text_id;

Query dynamic management views

Dynamic management views return server state information that can be used to monitor the health of a server instance, diagnose problems, and tune performance.

To query the dm_os_wait stats dynamic management view:

SELECT wait_type,
       wait_time_ms
FROM sys.dm_os_wait_stats;

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