sql-server-samples/samples/features/intelligent-query-processing/notebooks/Memory_Grant_Feedback.ipynb

Memory Grant Feedback

Memory grant feedback (MGF)adjusts memory grant sizes to learn and improve memory usage. This feature can adjust memory grant sizes for both batch and row mode operators, and eliminate the effects of memory grant misestimations (spills to TempDB) and overestimations (affects concurrency).

Memory grant feedback is a feature under the Intelligent Query Processing suite of features.

This example will show you how upgrading to Database Compatibility Level 150 could improve performance of queries executing in row mode, that are affected by memory grant misestimations. Upgrading to Database Compatibility Level 140 allows MGF for queries executing in batch mode, and Database Compatibility Level 150 allows MGF on queries executing in row mode.

More information about this feature is available here.

Step 1: Setup WideWorldImportersDW database

You could choose to use a container to evaluate this feature. Create an instance of SQL Server 2019 using a Docker image and restore the WideWorldImportersDW database backup

You will need the WideWorldImportersDW database for this exercise. If you don't have this sample database, then you download the sample database here.

Restore the copied WideWorldImportersDW database backup into the container and restore the backup.

Docker Commands

docker pull mcr.microsoft.com/mssql/server:2019-latest

docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=`<A Strong Password`>" -p 1445:1433 --name sql2019demo -d mcr.microsoft.com/mssql/server:2019-latest

docker cp ".\Downloads\WideWorldImportersDW-Full.bak" sql2019demo:/var/opt/mssql/data

Note: For Linux installations the default path to use is /var/opt/mssql

In [7]:

USE [master]
GO
IF EXISTS (SELECT [database_id] FROM sys.databases WHERE [name] = 'WideWorldImportersDW')
ALTER DATABASE [WideWorldImportersDW] SET SINGLE_USER WITH ROLLBACK IMMEDIATE
GO

DECLARE @datafilepath VARCHAR(8000) = CAST(SERVERPROPERTY('InstanceDefaultDataPath') AS VARCHAR(4000)) + 'WideWorldImportersDW.mdf'
DECLARE @logfilepath VARCHAR(8000) = CAST(SERVERPROPERTY('InstanceDefaultLogPath') AS VARCHAR(4000)) + 'WideWorldImportersDW.ldf'
DECLARE @inmemfilepath VARCHAR(8000) = CAST(SERVERPROPERTY('InstanceDefaultDataPath') AS VARCHAR(4000)) + 'WideWorldImportersDW_InMemory_Data_1'
DECLARE @secondaryfilepath VARCHAR(8000) = CAST(SERVERPROPERTY('InstanceDefaultDataPath') AS VARCHAR(4000))+ 'WideWorldImportersDW_2.ndf'

-- Change @backupfile file path as needed
DECLARE @backupfile VARCHAR(8000) = 'E:\SampleDBs\WideWorldImportersDW-Full.bak'
RESTORE DATABASE WideWorldImportersDW
FROM DISK = @backupfile 
WITH MOVE 'WWI_Primary' TO @datafilepath,
    MOVE 'WWI_UserData' TO @secondaryfilepath,
    MOVE 'WWIDW_InMemory_Data_1' TO @inmemfilepath,
    MOVE 'WWI_Log' TO @logfilepath, NOUNLOAD, REPLACE, STATS = 10
GO

USE [master]
GO
ALTER DATABASE [WideWorldImportersDW] MODIFY FILE ( NAME = N'WWI_Log', SIZE = 4GB )
GO

Step 2: Enlarge the WideWorldImportersDW database

In [3]:

USE WideWorldImportersDW;
GO

/*
Assumes a fresh restore of WideWorldImportersDW
*/

IF OBJECT_ID('Fact.OrderHistory') IS NULL 
BEGIN
    SELECT [Order Key], [City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key]
    INTO Fact.OrderHistory
    FROM Fact.[Order];
END;

ALTER TABLE Fact.OrderHistory
ADD CONSTRAINT PK_Fact_OrderHistory PRIMARY KEY NONCLUSTERED ([Order Key] ASC, [Order Date Key] ASC) WITH (DATA_COMPRESSION = PAGE);
GO

CREATE INDEX IX_Stock_Item_Key
ON Fact.OrderHistory ([Stock Item Key])
INCLUDE(Quantity)
WITH (DATA_COMPRESSION = PAGE);
GO

CREATE INDEX IX_OrderHistory_Quantity
ON Fact.OrderHistory ([Quantity])
INCLUDE([Order Key])
WITH (DATA_COMPRESSION = PAGE);
GO

CREATE INDEX IX_OrderHistory_CustomerKey
ON Fact.OrderHistory([Customer Key])
INCLUDE ([Total Including Tax])
WITH (DATA_COMPRESSION = PAGE);
GO

IF (SELECT COUNT(*) FROM [Fact].[OrderHistory]) < 3702592
BEGIN
	DECLARE @i smallint
	SET @i = 0
	WHILE @i < 4
	BEGIN
		INSERT INTO [Fact].[OrderHistory] ([City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key])
		SELECT [City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key]
		FROM [Fact].[OrderHistory];

		SET @i = @i +1
	END;
END
GO

IF OBJECT_ID('Fact.OrderHistoryExtended') IS NULL 
BEGIN
    SELECT [Order Key], [City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key]
    INTO Fact.OrderHistoryExtended
    FROM Fact.[OrderHistory];
END;

ALTER TABLE Fact.OrderHistoryExtended
ADD CONSTRAINT PK_Fact_OrderHistoryExtended PRIMARY KEY NONCLUSTERED ([Order Key] ASC, [Order Date Key] ASC)
WITH (DATA_COMPRESSION = PAGE);
GO

CREATE INDEX IX_Stock_Item_Key
ON Fact.OrderHistoryExtended ([Stock Item Key])
INCLUDE (Quantity);
GO

IF (SELECT COUNT(*) FROM [Fact].[OrderHistory]) < 29620736
BEGIN
	DECLARE @i smallint
	SET @i = 0
	WHILE @i < 3
	BEGIN
		INSERT Fact.OrderHistoryExtended([City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key])
		SELECT [City Key], [Customer Key], [Stock Item Key], [Order Date Key], [Picked Date Key], [Salesperson Key], [Picker Key], [WWI Order ID], [WWI Backorder ID], Description, Package, Quantity, [Unit Price], [Tax Rate], [Total Excluding Tax], [Tax Amount], [Total Including Tax], [Lineage Key]
		FROM Fact.OrderHistoryExtended;

		SET @i = @i +1
	END;
END
GO

UPDATE Fact.OrderHistoryExtended
SET [WWI Order ID] = [Order Key];
GO

-- Repeat the following until log shrinks. These demos don't require much log space.
CHECKPOINT
GO
DBCC SHRINKFILE (N'WWI_Log' , 0, TRUNCATEONLY)
GO
SELECT * FROM sys.dm_db_log_space_usage
GO

Step 3: Skew cardinality estimations

This will provide skewed statistical information to the Cardinality Estimator (CE).

Statistics are fundamental building blocks for the CE to output good estimations over the expected number of rows will be used from a table for a given query. Therefore, it's fundamental for the CE to have statistics that accurately portray the underlying data distribution of a column or set of columns. If those statistics are skewed, then cardinality estimations will likely be wrong and the Query Optimizer will likely make wrong decisions. The result is an inneficient plan for a given query.

In [1]:

USE [WideWorldImportersDW];
GO
UPDATE STATISTICS Fact.OrderHistory 
WITH ROWCOUNT = 1;
GO

Commands completed successfully.

Commands completed successfully.

Total execution time: 00:00:00.124

Step 4: Execute the query and observe the query execution plan

In [9]:

USE [WideWorldImportersDW];
GO
ALTER DATABASE [WideWorldImportersDW] SET COMPATIBILITY_LEVEL = 150;
GO
ALTER DATABASE SCOPED CONFIGURATION CLEAR PROCEDURE_CACHE;
GO

SELECT   
	fo.[Order Key], fo.Description,
	si.[Lead Time Days]
FROM Fact.OrderHistory AS fo
INNER HASH JOIN Dimension.[Stock Item] AS si 
	ON fo.[Stock Item Key] = si.[Stock Item Key]
WHERE fo.[Lineage Key] = 9
	AND si.[Lead Time Days] > 19;
GO

Out [9]:

Commands completed successfully.

Commands completed successfully.

Commands completed successfully.

Warning: The join order has been enforced because a local join hint is used.

(66416 rows affected)

Displaying Top 500 rows.

Total execution time: 00:00:43.190

Order Key	Description	Lead Time Days
3699679	Tape dispenser (Black)	20
3700053	Tape dispenser (Black)	20
3700057	Tape dispenser (Black)	20
3700061	Tape dispenser (Black)	20
3701657	Tape dispenser (Black)	20
3701914	Tape dispenser (Black)	20
3702301	Tape dispenser (Black)	20
3592539	Tape dispenser (Black)	20
3592540	Tape dispenser (Black)	20
3592541	Tape dispenser (Black)	20
3592542	Tape dispenser (Black)	20
3592543	Tape dispenser (Black)	20
3592544	Tape dispenser (Black)	20
3592545	Tape dispenser (Black)	20
3592546	Tape dispenser (Black)	20
3592547	Tape dispenser (Black)	20
3592548	Tape dispenser (Black)	20
3592549	Tape dispenser (Black)	20
3592550	Tape dispenser (Black)	20
3592551	Tape dispenser (Black)	20
3592552	Tape dispenser (Black)	20
3592553	Tape dispenser (Black)	20
3592554	Tape dispenser (Black)	20
3592555	Tape dispenser (Black)	20
3592556	Tape dispenser (Black)	20
3592557	Tape dispenser (Black)	20
3592558	Tape dispenser (Black)	20
3592559	Tape dispenser (Black)	20
3592560	Tape dispenser (Black)	20
3592561	Tape dispenser (Black)	20
3592562	Tape dispenser (Black)	20
3592563	Tape dispenser (Black)	20
3592564	Tape dispenser (Black)	20
3592565	Tape dispenser (Black)	20
3592566	Tape dispenser (Black)	20
3592567	Tape dispenser (Black)	20
3592568	Tape dispenser (Black)	20
3592802	Tape dispenser (Black)	20
3592804	Tape dispenser (Black)	20
3593217	Tape dispenser (Black)	20
3593522	Tape dispenser (Black)	20
3593523	Tape dispenser (Black)	20
3593524	Tape dispenser (Black)	20
3593525	Tape dispenser (Black)	20
3593526	Tape dispenser (Black)	20
3593527	Tape dispenser (Black)	20
3593528	Tape dispenser (Black)	20
3593529	Tape dispenser (Black)	20
3593530	Tape dispenser (Black)	20
3593531	Tape dispenser (Black)	20
3593532	Tape dispenser (Black)	20
3593533	Tape dispenser (Black)	20
3593534	Tape dispenser (Black)	20
3593535	Tape dispenser (Black)	20
3593536	Tape dispenser (Black)	20
3593537	Tape dispenser (Black)	20
3593538	Tape dispenser (Black)	20
3593539	Tape dispenser (Black)	20
3593540	Tape dispenser (Black)	20
3593541	Tape dispenser (Black)	20
3593542	Tape dispenser (Black)	20
3593543	Tape dispenser (Black)	20
3593544	Tape dispenser (Black)	20
3593545	Tape dispenser (Black)	20
3593546	Tape dispenser (Black)	20
3593841	Tape dispenser (Black)	20
3593862	Tape dispenser (Black)	20
3593865	Tape dispenser (Black)	20
3698037	Tape dispenser (Black)	20
3698043	Tape dispenser (Black)	20
3698125	Tape dispenser (Black)	20
3698584	Tape dispenser (Black)	20
3698595	Tape dispenser (Black)	20
3698604	Tape dispenser (Black)	20
3699617	Tape dispenser (Black)	20
3699619	Tape dispenser (Black)	20
3695553	Tape dispenser (Black)	20
3695559	Tape dispenser (Black)	20
3696413	Tape dispenser (Black)	20
3696414	Tape dispenser (Black)	20
3696415	Tape dispenser (Black)	20
3696416	Tape dispenser (Black)	20
3696417	Tape dispenser (Black)	20
3696418	Tape dispenser (Black)	20
3696419	Tape dispenser (Black)	20
3696420	Tape dispenser (Black)	20
3696421	Tape dispenser (Black)	20
3696422	Tape dispenser (Black)	20
3696423	Tape dispenser (Black)	20
3696424	Tape dispenser (Black)	20
3696425	Tape dispenser (Black)	20
3696426	Tape dispenser (Black)	20
3696427	Tape dispenser (Black)	20
3696428	Tape dispenser (Black)	20
3696429	Tape dispenser (Black)	20
3696430	Tape dispenser (Black)	20
3696431	Tape dispenser (Black)	20
3696432	Tape dispenser (Black)	20
3696433	Tape dispenser (Black)	20
3696434	Tape dispenser (Black)	20
3696435	Tape dispenser (Black)	20
3696436	Tape dispenser (Black)	20
3696437	Tape dispenser (Black)	20
3696438	Tape dispenser (Black)	20
3696439	Tape dispenser (Black)	20
3696440	Tape dispenser (Black)	20
3696441	Tape dispenser (Black)	20
3696442	Tape dispenser (Black)	20
3696443	Tape dispenser (Black)	20
3696444	Tape dispenser (Black)	20
3696445	Tape dispenser (Black)	20
3696446	Tape dispenser (Black)	20
3696598	Tape dispenser (Black)	20
3696599	Tape dispenser (Black)	20
3697127	Tape dispenser (Black)	20
3694271	Tape dispenser (Black)	20
3695203	Tape dispenser (Black)	20
3682899	Tape dispenser (Black)	20
3683029	Tape dispenser (Black)	20
3683434	Tape dispenser (Black)	20
3684144	Tape dispenser (Black)	20
3684145	Tape dispenser (Black)	20
3684146	Tape dispenser (Black)	20
3684147	Tape dispenser (Black)	20
3684148	Tape dispenser (Black)	20
3684149	Tape dispenser (Black)	20
3684150	Tape dispenser (Black)	20
3684151	Tape dispenser (Black)	20
3684152	Tape dispenser (Black)	20
3684153	Tape dispenser (Black)	20
3684154	Tape dispenser (Black)	20
3684155	Tape dispenser (Black)	20
3684156	Tape dispenser (Black)	20
3684157	Tape dispenser (Black)	20
3684158	Tape dispenser (Black)	20
3684725	Tape dispenser (Black)	20
3684726	Tape dispenser (Black)	20
3690046	Tape dispenser (Black)	20
3690658	Tape dispenser (Black)	20
3690659	Tape dispenser (Black)	20
3690660	Tape dispenser (Black)	20
3690661	Tape dispenser (Black)	20
3690662	Tape dispenser (Black)	20
3690663	Tape dispenser (Black)	20
3690664	Tape dispenser (Black)	20
3690665	Tape dispenser (Black)	20
3690666	Tape dispenser (Black)	20
3690667	Tape dispenser (Black)	20
3690668	Tape dispenser (Black)	20
3690669	Tape dispenser (Black)	20
3690670	Tape dispenser (Black)	20
3690671	Tape dispenser (Black)	20
3690672	Tape dispenser (Black)	20
3690673	Tape dispenser (Black)	20
3690674	Tape dispenser (Black)	20
3690675	Tape dispenser (Black)	20
3690676	Tape dispenser (Black)	20
3690677	Tape dispenser (Black)	20
3690678	Tape dispenser (Black)	20
3690679	Tape dispenser (Black)	20
3690680	Tape dispenser (Black)	20
3690681	Tape dispenser (Black)	20
3690682	Tape dispenser (Black)	20
3690683	Tape dispenser (Black)	20
3690684	Tape dispenser (Black)	20
3690685	Tape dispenser (Black)	20
3690686	Tape dispenser (Black)	20
3690687	Tape dispenser (Black)	20
3690688	Tape dispenser (Black)	20
3690689	Tape dispenser (Black)	20
3690690	Tape dispenser (Black)	20
3690934	Tape dispenser (Black)	20
3690937	Tape dispenser (Black)	20
3691773	Tape dispenser (Black)	20
3691774	Tape dispenser (Black)	20
3691775	Tape dispenser (Black)	20
3691889	Tape dispenser (Black)	20
3691895	Tape dispenser (Black)	20
3692373	Tape dispenser (Black)	20
3685053	Tape dispenser (Black)	20
3685486	Tape dispenser (Black)	20
3599502	Tape dispenser (Black)	20
3600831	Tape dispenser (Black)	20
3677792	Tape dispenser (Black)	20
3678351	Tape dispenser (Black)	20
3671216	Tape dispenser (Black)	20
3671217	Tape dispenser (Black)	20
3671218	Tape dispenser (Black)	20
3671219	Tape dispenser (Black)	20
3671220	Tape dispenser (Black)	20
3671221	Tape dispenser (Black)	20
3671222	Tape dispenser (Black)	20
3671223	Tape dispenser (Black)	20
3671224	Tape dispenser (Black)	20
3671225	Tape dispenser (Black)	20
3671226	Tape dispenser (Black)	20
3671227	Tape dispenser (Black)	20
3671228	Tape dispenser (Black)	20
3671229	Tape dispenser (Black)	20
3671230	Tape dispenser (Black)	20
3671231	Tape dispenser (Black)	20
3671232	Tape dispenser (Black)	20
3671233	Tape dispenser (Black)	20
3671234	Tape dispenser (Black)	20
3671235	Tape dispenser (Black)	20
3671236	Tape dispenser (Black)	20
3671237	Tape dispenser (Black)	20
3671238	Tape dispenser (Black)	20
3671239	Tape dispenser (Black)	20
3671240	Tape dispenser (Black)	20
3672306	Tape dispenser (Black)	20
3672479	Tape dispenser (Black)	20
3672482	Tape dispenser (Black)	20
3664001	Tape dispenser (Black)	20
3658774	Tape dispenser (Black)	20
3640091	Tape dispenser (Black)	20
3640092	Tape dispenser (Black)	20
3640093	Tape dispenser (Black)	20
3640094	Tape dispenser (Black)	20
3640095	Tape dispenser (Black)	20
3640370	Tape dispenser (Black)	20
3640371	Tape dispenser (Black)	20
3640372	Tape dispenser (Black)	20
3640373	Tape dispenser (Black)	20
3640374	Tape dispenser (Black)	20
3640375	Tape dispenser (Black)	20
3640376	Tape dispenser (Black)	20
3640377	Tape dispenser (Black)	20
3640378	Tape dispenser (Black)	20
3640379	Tape dispenser (Black)	20
3640380	Tape dispenser (Black)	20
3640381	Tape dispenser (Black)	20
3640382	Tape dispenser (Black)	20
3640383	Tape dispenser (Black)	20
3640384	Tape dispenser (Black)	20
3640385	Tape dispenser (Black)	20
3640386	Tape dispenser (Black)	20
3640387	Tape dispenser (Black)	20
3640388	Tape dispenser (Black)	20
3640389	Tape dispenser (Black)	20
3640390	Tape dispenser (Black)	20
3640391	Tape dispenser (Black)	20
3640392	Tape dispenser (Black)	20
3640393	Tape dispenser (Black)	20
3651888	Tape dispenser (Black)	20
3651889	Tape dispenser (Black)	20
3649229	Tape dispenser (Black)	20
3639013	Tape dispenser (Black)	20
3639014	Tape dispenser (Black)	20
3639015	Tape dispenser (Black)	20
3639016	Tape dispenser (Black)	20
3639017	Tape dispenser (Black)	20
3639018	Tape dispenser (Black)	20
3639019	Tape dispenser (Black)	20
3639020	Tape dispenser (Black)	20
3639021	Tape dispenser (Black)	20
3639022	Tape dispenser (Black)	20
3639023	Tape dispenser (Black)	20
3639024	Tape dispenser (Black)	20
3639025	Tape dispenser (Black)	20
3639026	Tape dispenser (Black)	20
3639027	Tape dispenser (Black)	20
3639028	Tape dispenser (Black)	20
3639029	Tape dispenser (Black)	20
3639030	Tape dispenser (Black)	20
3639031	Tape dispenser (Black)	20
3639032	Tape dispenser (Black)	20
3639033	Tape dispenser (Black)	20
3639593	Tape dispenser (Black)	20
3639594	Tape dispenser (Black)	20
3639595	Tape dispenser (Black)	20
3639596	Tape dispenser (Black)	20
3639597	Tape dispenser (Black)	20
3639598	Tape dispenser (Black)	20
3639599	Tape dispenser (Black)	20
3639600	Tape dispenser (Black)	20
3639601	Tape dispenser (Black)	20
3639602	Tape dispenser (Black)	20
3639603	Tape dispenser (Black)	20
3639604	Tape dispenser (Black)	20
3639605	Tape dispenser (Black)	20
3639606	Tape dispenser (Black)	20
3639607	Tape dispenser (Black)	20
3639608	Tape dispenser (Black)	20
3639609	Tape dispenser (Black)	20
3639610	Tape dispenser (Black)	20
3639611	Tape dispenser (Black)	20
3639612	Tape dispenser (Black)	20
3639613	Tape dispenser (Black)	20
3639614	Tape dispenser (Black)	20
3639615	Tape dispenser (Black)	20
3639616	Tape dispenser (Black)	20
3639617	Tape dispenser (Black)	20
3639618	Tape dispenser (Black)	20
3639619	Tape dispenser (Black)	20
3639620	Tape dispenser (Black)	20
3639621	Tape dispenser (Black)	20
3639622	Tape dispenser (Black)	20
3639623	Tape dispenser (Black)	20
3639624	Tape dispenser (Black)	20
3639625	Tape dispenser (Black)	20
3639626	Tape dispenser (Black)	20
3639627	Tape dispenser (Black)	20
3639628	Tape dispenser (Black)	20
3639840	Tape dispenser (Black)	20
3639841	Tape dispenser (Black)	20
3639842	Tape dispenser (Black)	20
3639843	Tape dispenser (Black)	20
3639844	Tape dispenser (Black)	20
3639845	Tape dispenser (Black)	20
3639846	Tape dispenser (Black)	20
3639847	Tape dispenser (Black)	20
3639848	Tape dispenser (Black)	20
3639849	Tape dispenser (Black)	20
3639850	Tape dispenser (Black)	20
3639851	Tape dispenser (Black)	20
3639852	Tape dispenser (Black)	20
3639853	Tape dispenser (Black)	20
3639854	Tape dispenser (Black)	20
3639855	Tape dispenser (Black)	20
3639856	Tape dispenser (Black)	20
3639857	Tape dispenser (Black)	20
3639858	Tape dispenser (Black)	20
3639859	Tape dispenser (Black)	20
3639860	Tape dispenser (Black)	20
3639861	Tape dispenser (Black)	20
3639862	Tape dispenser (Black)	20
3639863	Tape dispenser (Black)	20
3639864	Tape dispenser (Black)	20
3639865	Tape dispenser (Black)	20
3639866	Tape dispenser (Black)	20
3639867	Tape dispenser (Black)	20
3639868	Tape dispenser (Black)	20
3639869	Tape dispenser (Black)	20
3639870	Tape dispenser (Black)	20
3639871	Tape dispenser (Black)	20
3639872	Tape dispenser (Black)	20
3639873	Tape dispenser (Black)	20
3639874	Tape dispenser (Black)	20
3639875	Tape dispenser (Black)	20
3640060	Tape dispenser (Black)	20
3640061	Tape dispenser (Black)	20
3640062	Tape dispenser (Black)	20
3640063	Tape dispenser (Black)	20
3640064	Tape dispenser (Black)	20
3640065	Tape dispenser (Black)	20
3640066	Tape dispenser (Black)	20
3640067	Tape dispenser (Black)	20
3640068	Tape dispenser (Black)	20
3640069	Tape dispenser (Black)	20
3640070	Tape dispenser (Black)	20
3640071	Tape dispenser (Black)	20
3640072	Tape dispenser (Black)	20
3640073	Tape dispenser (Black)	20
3640074	Tape dispenser (Black)	20
3640075	Tape dispenser (Black)	20
3640076	Tape dispenser (Black)	20
3640077	Tape dispenser (Black)	20
3640078	Tape dispenser (Black)	20
3640079	Tape dispenser (Black)	20
3640080	Tape dispenser (Black)	20
3640081	Tape dispenser (Black)	20
3640082	Tape dispenser (Black)	20
3640083	Tape dispenser (Black)	20
3640084	Tape dispenser (Black)	20
3640085	Tape dispenser (Black)	20
3640086	Tape dispenser (Black)	20
3640087	Tape dispenser (Black)	20
3640088	Tape dispenser (Black)	20
3640089	Tape dispenser (Black)	20
3640090	Tape dispenser (Black)	20
3629003	Tape dispenser (Black)	20
3614394	Tape dispenser (Black)	20
3614813	Tape dispenser (Black)	20
3614814	Tape dispenser (Black)	20
3614815	Tape dispenser (Black)	20
3614816	Tape dispenser (Black)	20
3615212	Tape dispenser (Black)	20
3615213	Tape dispenser (Black)	20
3615214	Tape dispenser (Black)	20
3615215	Tape dispenser (Black)	20
3615216	Tape dispenser (Black)	20
3615217	Tape dispenser (Black)	20
3615218	Tape dispenser (Black)	20
3615219	Tape dispenser (Black)	20
3615220	Tape dispenser (Black)	20
3615221	Tape dispenser (Black)	20
3615222	Tape dispenser (Black)	20
3615223	Tape dispenser (Black)	20
3615224	Tape dispenser (Black)	20
3615225	Tape dispenser (Black)	20
3615226	Tape dispenser (Black)	20
3615227	Tape dispenser (Black)	20
3615228	Tape dispenser (Black)	20
3615229	Tape dispenser (Black)	20
3615230	Tape dispenser (Black)	20
3615231	Tape dispenser (Black)	20
3615263	Tape dispenser (Black)	20
3615264	Tape dispenser (Black)	20
3615265	Tape dispenser (Black)	20
3615266	Tape dispenser (Black)	20
3615267	Tape dispenser (Black)	20
3615268	Tape dispenser (Black)	20
3615269	Tape dispenser (Black)	20
3615270	Tape dispenser (Black)	20
3615271	Tape dispenser (Black)	20
3615272	Tape dispenser (Black)	20
3615273	Tape dispenser (Black)	20
3615274	Tape dispenser (Black)	20
3617683	Tape dispenser (Black)	20
3618332	Tape dispenser (Black)	20
3618344	Tape dispenser (Black)	20
3619498	Tape dispenser (Black)	20
3609832	Tape dispenser (Black)	20
3609833	Tape dispenser (Black)	20
3609834	Tape dispenser (Black)	20
3609835	Tape dispenser (Black)	20
3609836	Tape dispenser (Black)	20
3609837	Tape dispenser (Black)	20
3609838	Tape dispenser (Black)	20
3609839	Tape dispenser (Black)	20
3609840	Tape dispenser (Black)	20
3609841	Tape dispenser (Black)	20
3609842	Tape dispenser (Black)	20
3609843	Tape dispenser (Black)	20
3609844	Tape dispenser (Black)	20
3609845	Tape dispenser (Black)	20
3609878	Tape dispenser (Black)	20
3609879	Tape dispenser (Black)	20
3609880	Tape dispenser (Black)	20
3609881	Tape dispenser (Black)	20
3609882	Tape dispenser (Black)	20
3609883	Tape dispenser (Black)	20
3609884	Tape dispenser (Black)	20
3609885	Tape dispenser (Black)	20
3609889	Tape dispenser (Black)	20
3609890	Tape dispenser (Black)	20
3611250	Tape dispenser (Black)	20
3611251	Tape dispenser (Black)	20
3611252	Tape dispenser (Black)	20
3611253	Tape dispenser (Black)	20
3611254	Tape dispenser (Black)	20
3611255	Tape dispenser (Black)	20
3611256	Tape dispenser (Black)	20
3611288	Tape dispenser (Black)	20
3611289	Tape dispenser (Black)	20
3611290	Tape dispenser (Black)	20
3611291	Tape dispenser (Black)	20
3611292	Tape dispenser (Black)	20
3611293	Tape dispenser (Black)	20
3611294	Tape dispenser (Black)	20
3611295	Tape dispenser (Black)	20
3611296	Tape dispenser (Black)	20
3611661	Tape dispenser (Black)	20
3611662	Tape dispenser (Black)	20
3611663	Tape dispenser (Black)	20
3611664	Tape dispenser (Black)	20
3611665	Tape dispenser (Black)	20
3611666	Tape dispenser (Black)	20
3611667	Tape dispenser (Black)	20
3611668	Tape dispenser (Black)	20
3611669	Tape dispenser (Black)	20
3611670	Tape dispenser (Black)	20
3611671	Tape dispenser (Black)	20
3611672	Tape dispenser (Black)	20
3612451	Tape dispenser (Black)	20
3604228	Tape dispenser (Black)	20
3604229	Tape dispenser (Black)	20
3604230	Tape dispenser (Black)	20
3604231	Tape dispenser (Black)	20
3604232	Tape dispenser (Black)	20
3604233	Tape dispenser (Black)	20
3604234	Tape dispenser (Black)	20
3604235	Tape dispenser (Black)	20
3604236	Tape dispenser (Black)	20
3604237	Tape dispenser (Black)	20
3604238	Tape dispenser (Black)	20
3604239	Tape dispenser (Black)	20
3604240	Tape dispenser (Black)	20
3604618	Tape dispenser (Black)	20
3605331	Tape dispenser (Black)	20
3605730	Tape dispenser (Black)	20
3605731	Tape dispenser (Black)	20
3605732	Tape dispenser (Black)	20
3605733	Tape dispenser (Black)	20
3605734	Tape dispenser (Black)	20
3605735	Tape dispenser (Black)	20
3605736	Tape dispenser (Black)	20
3605737	Tape dispenser (Black)	20
3606545	Tape dispenser (Black)	20
3606546	Tape dispenser (Black)	20
3606547	Tape dispenser (Black)	20
3606548	Tape dispenser (Black)	20
3606549	Tape dispenser (Black)	20
3606550	Tape dispenser (Black)	20
3606551	Tape dispenser (Black)	20
3606552	Tape dispenser (Black)	20
3606553	Tape dispenser (Black)	20
3606554	Tape dispenser (Black)	20
3606555	Tape dispenser (Black)	20

Observe the query execution plan (or actual plan).

Notice the yellow triangle on the Hash Match operator, signaling a warning.

Hovering over the operator brings up additional information. We see the warning detail:

"Operator used tempdb to spill data during execution with spill level 1 and 1 spilled thread(s), Hash wrote 52000 pages to and read 52000 pages from tempdb with granted memory 1024KB and used memory 968KB"

This is a sizable spill that translates into I/O, which in most systems means slow performance.

Now click on the SELECT node, and look at properties of the entire plan. Specifically in the MemoryGrantInfo properties, note the GrantedMemory is 1056 KB (about 1 MB) and IsMemoryGrantFeedbackAdjusted has the "NoFirstExecution" state.

Because this was the first execution, the MGF feature didn't have a chance to learn before it executed. However, note what happens when the query is executed a few more times.

Step 5: Execute the query again

Run the same query from Step 3 and then observe the query plan's MemoryGrantInfo properties.

In [10]:

USE [WideWorldImportersDW]
GO

SELECT   
	fo.[Order Key], fo.Description,
	si.[Lead Time Days]
FROM Fact.OrderHistory AS fo
INNER HASH JOIN Dimension.[Stock Item] AS si 
	ON fo.[Stock Item Key] = si.[Stock Item Key]
WHERE fo.[Lineage Key] = 9
	AND si.[Lead Time Days] > 19;
GO

Out [10]:

Commands completed successfully.

(66416 rows affected)

Displaying Top 500 rows.

Total execution time: 00:00:05.131

Order Key	Description	Lead Time Days
231599	Air cushion machine (Blue)	20
232215	Air cushion machine (Blue)	20
232290	Air cushion machine (Blue)	20
231769	Air cushion machine (Blue)	20
232997	Air cushion machine (Blue)	20
234019	Air cushion machine (Blue)	20
3702343	Air cushion machine (Blue)	20
3702543	Air cushion machine (Blue)	20
3700753	Air cushion machine (Blue)	20
3700850	Air cushion machine (Blue)	20
3701058	Air cushion machine (Blue)	20
3701547	Air cushion machine (Blue)	20
3701851	Air cushion machine (Blue)	20
3701910	Air cushion machine (Blue)	20
3699067	Air cushion machine (Blue)	20
3699971	Air cushion machine (Blue)	20
3700077	Air cushion machine (Blue)	20
3700420	Air cushion machine (Blue)	20
3700588	Air cushion machine (Blue)	20
3700647	Air cushion machine (Blue)	20
3697314	Air cushion machine (Blue)	20
3697324	Air cushion machine (Blue)	20
3697777	Air cushion machine (Blue)	20
3698106	Air cushion machine (Blue)	20
3698246	Air cushion machine (Blue)	20
3698908	Air cushion machine (Blue)	20
3696765	Air cushion machine (Blue)	20
3696768	Air cushion machine (Blue)	20
3696995	Air cushion machine (Blue)	20
3697022	Air cushion machine (Blue)	20
3697026	Air cushion machine (Blue)	20
3697101	Air cushion machine (Blue)	20
3696050	Air cushion machine (Blue)	20
3696120	Air cushion machine (Blue)	20
3696259	Air cushion machine (Blue)	20
3696550	Air cushion machine (Blue)	20
3696658	Air cushion machine (Blue)	20
3696679	Air cushion machine (Blue)	20
3694691	Air cushion machine (Blue)	20
3694692	Air cushion machine (Blue)	20
3695473	Air cushion machine (Blue)	20
3695710	Air cushion machine (Blue)	20
3695804	Air cushion machine (Blue)	20
3695851	Air cushion machine (Blue)	20
3692422	Air cushion machine (Blue)	20
3692780	Air cushion machine (Blue)	20
3693776	Air cushion machine (Blue)	20
3694322	Air cushion machine (Blue)	20
3694458	Air cushion machine (Blue)	20
3694562	Air cushion machine (Blue)	20
3690456	Air cushion machine (Blue)	20
3691479	Air cushion machine (Blue)	20
3691497	Air cushion machine (Blue)	20
3691545	Air cushion machine (Blue)	20
3691570	Air cushion machine (Blue)	20
3691981	Air cushion machine (Blue)	20
3688998	Air cushion machine (Blue)	20
3689106	Air cushion machine (Blue)	20
3689335	Air cushion machine (Blue)	20
3689338	Air cushion machine (Blue)	20
3689554	Air cushion machine (Blue)	20
3690236	Air cushion machine (Blue)	20
3687237	Air cushion machine (Blue)	20
3687640	Air cushion machine (Blue)	20
3687707	Air cushion machine (Blue)	20
3688114	Air cushion machine (Blue)	20
3688364	Air cushion machine (Blue)	20
3688785	Air cushion machine (Blue)	20
3684826	Air cushion machine (Blue)	20
3684915	Air cushion machine (Blue)	20
3685158	Air cushion machine (Blue)	20
3685719	Air cushion machine (Blue)	20
3686065	Air cushion machine (Blue)	20
3686257	Air cushion machine (Blue)	20
3683223	Air cushion machine (Blue)	20
3683278	Air cushion machine (Blue)	20
3683523	Air cushion machine (Blue)	20
3684268	Air cushion machine (Blue)	20
3684463	Air cushion machine (Blue)	20
3684800	Air cushion machine (Blue)	20
3681672	Air cushion machine (Blue)	20
3681962	Air cushion machine (Blue)	20
3682199	Air cushion machine (Blue)	20
3682788	Air cushion machine (Blue)	20
3683110	Air cushion machine (Blue)	20
3683211	Air cushion machine (Blue)	20
3681036	Air cushion machine (Blue)	20
3681045	Air cushion machine (Blue)	20
3681088	Air cushion machine (Blue)	20
3681155	Air cushion machine (Blue)	20
3681286	Air cushion machine (Blue)	20
3681584	Air cushion machine (Blue)	20
3680465	Air cushion machine (Blue)	20
3680480	Air cushion machine (Blue)	20
3680549	Air cushion machine (Blue)	20
3680742	Air cushion machine (Blue)	20
3680761	Air cushion machine (Blue)	20
3680966	Air cushion machine (Blue)	20
3679368	Air cushion machine (Blue)	20
3679389	Air cushion machine (Blue)	20
3679607	Air cushion machine (Blue)	20
3679651	Air cushion machine (Blue)	20
3680068	Air cushion machine (Blue)	20
3680079	Air cushion machine (Blue)	20
3678179	Air cushion machine (Blue)	20
3678512	Air cushion machine (Blue)	20
3678528	Air cushion machine (Blue)	20
3678659	Air cushion machine (Blue)	20
3678989	Air cushion machine (Blue)	20
3679366	Air cushion machine (Blue)	20
3676701	Air cushion machine (Blue)	20
3676986	Air cushion machine (Blue)	20
3677734	Air cushion machine (Blue)	20
3677894	Air cushion machine (Blue)	20
3677898	Air cushion machine (Blue)	20
3677989	Air cushion machine (Blue)	20
3674511	Air cushion machine (Blue)	20
3674822	Air cushion machine (Blue)	20
3675140	Air cushion machine (Blue)	20
3675405	Air cushion machine (Blue)	20
3675540	Air cushion machine (Blue)	20
3675937	Air cushion machine (Blue)	20
3673205	Air cushion machine (Blue)	20
3673279	Air cushion machine (Blue)	20
3673293	Air cushion machine (Blue)	20
3673435	Air cushion machine (Blue)	20
3674030	Air cushion machine (Blue)	20
3674039	Air cushion machine (Blue)	20
3670177	Air cushion machine (Blue)	20
3670414	Air cushion machine (Blue)	20
3670422	Air cushion machine (Blue)	20
3672950	Air cushion machine (Blue)	20
3673006	Air cushion machine (Blue)	20
3673178	Air cushion machine (Blue)	20
3669324	Air cushion machine (Blue)	20
3669610	Air cushion machine (Blue)	20
3669666	Air cushion machine (Blue)	20
3669670	Air cushion machine (Blue)	20
3670079	Air cushion machine (Blue)	20
3670083	Air cushion machine (Blue)	20
3667779	Air cushion machine (Blue)	20
3668920	Air cushion machine (Blue)	20
3668927	Air cushion machine (Blue)	20
3669023	Air cushion machine (Blue)	20
3669112	Air cushion machine (Blue)	20
3669130	Air cushion machine (Blue)	20
3666914	Air cushion machine (Blue)	20
3666921	Air cushion machine (Blue)	20
3666996	Air cushion machine (Blue)	20
3667090	Air cushion machine (Blue)	20
3667312	Air cushion machine (Blue)	20
3667526	Air cushion machine (Blue)	20
3666509	Air cushion machine (Blue)	20
3666527	Air cushion machine (Blue)	20
3666535	Air cushion machine (Blue)	20
3666603	Air cushion machine (Blue)	20
3666619	Air cushion machine (Blue)	20
3666812	Air cushion machine (Blue)	20
3666197	Air cushion machine (Blue)	20
3666199	Air cushion machine (Blue)	20
3666216	Air cushion machine (Blue)	20
3666396	Air cushion machine (Blue)	20
3666410	Air cushion machine (Blue)	20
3666434	Air cushion machine (Blue)	20
3665882	Air cushion machine (Blue)	20
3665935	Air cushion machine (Blue)	20
3665940	Air cushion machine (Blue)	20
3665941	Air cushion machine (Blue)	20
3666018	Air cushion machine (Blue)	20
3666116	Air cushion machine (Blue)	20
3664981	Air cushion machine (Blue)	20
3665211	Air cushion machine (Blue)	20
3665527	Air cushion machine (Blue)	20
3665613	Air cushion machine (Blue)	20
3665702	Air cushion machine (Blue)	20
3665818	Air cushion machine (Blue)	20
3663893	Air cushion machine (Blue)	20
3664164	Air cushion machine (Blue)	20
3664506	Air cushion machine (Blue)	20
3664621	Air cushion machine (Blue)	20
3664793	Air cushion machine (Blue)	20
3664880	Air cushion machine (Blue)	20
3663498	Air cushion machine (Blue)	20
3663544	Air cushion machine (Blue)	20
3663669	Air cushion machine (Blue)	20
3663699	Air cushion machine (Blue)	20
3663710	Air cushion machine (Blue)	20
3663788	Air cushion machine (Blue)	20
3663046	Air cushion machine (Blue)	20
3663112	Air cushion machine (Blue)	20
3663402	Air cushion machine (Blue)	20
3663406	Air cushion machine (Blue)	20
3663472	Air cushion machine (Blue)	20
3663496	Air cushion machine (Blue)	20
3662398	Air cushion machine (Blue)	20
3662447	Air cushion machine (Blue)	20
3662454	Air cushion machine (Blue)	20
3662731	Air cushion machine (Blue)	20
3662768	Air cushion machine (Blue)	20
3662829	Air cushion machine (Blue)	20
3660952	Air cushion machine (Blue)	20
3661009	Air cushion machine (Blue)	20
3661117	Air cushion machine (Blue)	20
3661119	Air cushion machine (Blue)	20
3661801	Air cushion machine (Blue)	20
3661812	Air cushion machine (Blue)	20
3660277	Air cushion machine (Blue)	20
3660279	Air cushion machine (Blue)	20
3660429	Air cushion machine (Blue)	20
3660563	Air cushion machine (Blue)	20
3660825	Air cushion machine (Blue)	20
3660885	Air cushion machine (Blue)	20
3658272	Air cushion machine (Blue)	20
3659012	Air cushion machine (Blue)	20
3659243	Air cushion machine (Blue)	20
3659280	Air cushion machine (Blue)	20
3659317	Air cushion machine (Blue)	20
3659779	Air cushion machine (Blue)	20
3657470	Air cushion machine (Blue)	20
3657605	Air cushion machine (Blue)	20
3657674	Air cushion machine (Blue)	20
3658056	Air cushion machine (Blue)	20
3658080	Air cushion machine (Blue)	20
3658167	Air cushion machine (Blue)	20
3651363	Air cushion machine (Blue)	20
3651368	Air cushion machine (Blue)	20
3651510	Air cushion machine (Blue)	20
3651768	Air cushion machine (Blue)	20
3651814	Air cushion machine (Blue)	20
3656538	Air cushion machine (Blue)	20
3648540	Air cushion machine (Blue)	20
3650877	Air cushion machine (Blue)	20
3650887	Air cushion machine (Blue)	20
3651263	Air cushion machine (Blue)	20
3651273	Air cushion machine (Blue)	20
3651279	Air cushion machine (Blue)	20
3647243	Air cushion machine (Blue)	20
3648002	Air cushion machine (Blue)	20
3648185	Air cushion machine (Blue)	20
3648189	Air cushion machine (Blue)	20
3648224	Air cushion machine (Blue)	20
3648530	Air cushion machine (Blue)	20
3645059	Air cushion machine (Blue)	20
3645233	Air cushion machine (Blue)	20
3645249	Air cushion machine (Blue)	20
3645450	Air cushion machine (Blue)	20
3645832	Air cushion machine (Blue)	20
3646284	Air cushion machine (Blue)	20
3644427	Air cushion machine (Blue)	20
3644508	Air cushion machine (Blue)	20
3644730	Air cushion machine (Blue)	20
3644756	Air cushion machine (Blue)	20
3644796	Air cushion machine (Blue)	20
3645043	Air cushion machine (Blue)	20
3643822	Air cushion machine (Blue)	20
3643826	Air cushion machine (Blue)	20
3644175	Air cushion machine (Blue)	20
3644190	Air cushion machine (Blue)	20
3644286	Air cushion machine (Blue)	20
3644407	Air cushion machine (Blue)	20
3643492	Air cushion machine (Blue)	20
3643544	Air cushion machine (Blue)	20
3643568	Air cushion machine (Blue)	20
3643592	Air cushion machine (Blue)	20
3643706	Air cushion machine (Blue)	20
3643766	Air cushion machine (Blue)	20
3643202	Air cushion machine (Blue)	20
3643279	Air cushion machine (Blue)	20
3643340	Air cushion machine (Blue)	20
3643368	Air cushion machine (Blue)	20
3643421	Air cushion machine (Blue)	20
3643455	Air cushion machine (Blue)	20
3641898	Air cushion machine (Blue)	20
3642378	Air cushion machine (Blue)	20
3642573	Air cushion machine (Blue)	20
3642686	Air cushion machine (Blue)	20
3642816	Air cushion machine (Blue)	20
3643052	Air cushion machine (Blue)	20
3641255	Air cushion machine (Blue)	20
3641498	Air cushion machine (Blue)	20
3641589	Air cushion machine (Blue)	20
3641596	Air cushion machine (Blue)	20
3641767	Air cushion machine (Blue)	20
3641891	Air cushion machine (Blue)	20
3640034	Air cushion machine (Blue)	20
3640201	Air cushion machine (Blue)	20
3640281	Air cushion machine (Blue)	20
3640300	Air cushion machine (Blue)	20
3640586	Air cushion machine (Blue)	20
3641036	Air cushion machine (Blue)	20
3639207	Air cushion machine (Blue)	20
3639253	Air cushion machine (Blue)	20
3639263	Air cushion machine (Blue)	20
3639531	Air cushion machine (Blue)	20
3639810	Air cushion machine (Blue)	20
3639924	Air cushion machine (Blue)	20
3638043	Air cushion machine (Blue)	20
3638084	Air cushion machine (Blue)	20
3638171	Air cushion machine (Blue)	20
3638177	Air cushion machine (Blue)	20
3638593	Air cushion machine (Blue)	20
3638949	Air cushion machine (Blue)	20
3636338	Air cushion machine (Blue)	20
3636457	Air cushion machine (Blue)	20
3636495	Air cushion machine (Blue)	20
3636942	Air cushion machine (Blue)	20
3637676	Air cushion machine (Blue)	20
3637973	Air cushion machine (Blue)	20
3635947	Air cushion machine (Blue)	20
3635955	Air cushion machine (Blue)	20
3636021	Air cushion machine (Blue)	20
3636253	Air cushion machine (Blue)	20
3636268	Air cushion machine (Blue)	20
3636285	Air cushion machine (Blue)	20
3634799	Air cushion machine (Blue)	20
3634859	Air cushion machine (Blue)	20
3635052	Air cushion machine (Blue)	20
3635089	Air cushion machine (Blue)	20
3635598	Air cushion machine (Blue)	20
3635725	Air cushion machine (Blue)	20
3633820	Air cushion machine (Blue)	20
3633868	Air cushion machine (Blue)	20
3634080	Air cushion machine (Blue)	20
3634544	Air cushion machine (Blue)	20
3634661	Air cushion machine (Blue)	20
3634679	Air cushion machine (Blue)	20
3633310	Air cushion machine (Blue)	20
3633328	Air cushion machine (Blue)	20
3633356	Air cushion machine (Blue)	20
3633568	Air cushion machine (Blue)	20
3633723	Air cushion machine (Blue)	20
3633784	Air cushion machine (Blue)	20
3632480	Air cushion machine (Blue)	20
3632734	Air cushion machine (Blue)	20
3632947	Air cushion machine (Blue)	20
3633024	Air cushion machine (Blue)	20
3633111	Air cushion machine (Blue)	20
3633301	Air cushion machine (Blue)	20
3626533	Air cushion machine (Blue)	20
3628167	Air cushion machine (Blue)	20
3628495	Air cushion machine (Blue)	20
3628504	Air cushion machine (Blue)	20
3629551	Air cushion machine (Blue)	20
3632326	Air cushion machine (Blue)	20
3626126	Air cushion machine (Blue)	20
3626362	Air cushion machine (Blue)	20
3626403	Air cushion machine (Blue)	20
3626420	Air cushion machine (Blue)	20
3626445	Air cushion machine (Blue)	20
3626525	Air cushion machine (Blue)	20
3625826	Air cushion machine (Blue)	20
3625907	Air cushion machine (Blue)	20
3625949	Air cushion machine (Blue)	20
3625960	Air cushion machine (Blue)	20
3626070	Air cushion machine (Blue)	20
3626077	Air cushion machine (Blue)	20
3625647	Air cushion machine (Blue)	20
3625650	Air cushion machine (Blue)	20
3625751	Air cushion machine (Blue)	20
3625752	Air cushion machine (Blue)	20
3625780	Air cushion machine (Blue)	20
3625807	Air cushion machine (Blue)	20
3625416	Air cushion machine (Blue)	20
3625455	Air cushion machine (Blue)	20
3625543	Air cushion machine (Blue)	20
3625548	Air cushion machine (Blue)	20
3625590	Air cushion machine (Blue)	20
3625635	Air cushion machine (Blue)	20
3625171	Air cushion machine (Blue)	20
3625255	Air cushion machine (Blue)	20
3625274	Air cushion machine (Blue)	20
3625301	Air cushion machine (Blue)	20
3625319	Air cushion machine (Blue)	20
3625331	Air cushion machine (Blue)	20
3624781	Air cushion machine (Blue)	20
3624853	Air cushion machine (Blue)	20
3624914	Air cushion machine (Blue)	20
3624969	Air cushion machine (Blue)	20
3624971	Air cushion machine (Blue)	20
3624999	Air cushion machine (Blue)	20
3624625	Air cushion machine (Blue)	20
3624713	Air cushion machine (Blue)	20
3624715	Air cushion machine (Blue)	20
3624724	Air cushion machine (Blue)	20
3624764	Air cushion machine (Blue)	20
3624778	Air cushion machine (Blue)	20
3624334	Air cushion machine (Blue)	20
3624392	Air cushion machine (Blue)	20
3624420	Air cushion machine (Blue)	20
3624458	Air cushion machine (Blue)	20
3624519	Air cushion machine (Blue)	20
3624621	Air cushion machine (Blue)	20
3624076	Air cushion machine (Blue)	20
3624116	Air cushion machine (Blue)	20
3624144	Air cushion machine (Blue)	20
3624202	Air cushion machine (Blue)	20
3624213	Air cushion machine (Blue)	20
3624299	Air cushion machine (Blue)	20
3623767	Air cushion machine (Blue)	20
3623854	Air cushion machine (Blue)	20
3623871	Air cushion machine (Blue)	20
3623883	Air cushion machine (Blue)	20
3623903	Air cushion machine (Blue)	20
3623994	Air cushion machine (Blue)	20
3623567	Air cushion machine (Blue)	20
3623593	Air cushion machine (Blue)	20
3623594	Air cushion machine (Blue)	20
3623645	Air cushion machine (Blue)	20
3623682	Air cushion machine (Blue)	20
3623731	Air cushion machine (Blue)	20
3623013	Air cushion machine (Blue)	20
3623029	Air cushion machine (Blue)	20
3623089	Air cushion machine (Blue)	20
3623283	Air cushion machine (Blue)	20
3623340	Air cushion machine (Blue)	20
3623352	Air cushion machine (Blue)	20
3622793	Air cushion machine (Blue)	20
3622823	Air cushion machine (Blue)	20
3622837	Air cushion machine (Blue)	20
3622861	Air cushion machine (Blue)	20
3622881	Air cushion machine (Blue)	20
3622887	Air cushion machine (Blue)	20
3621323	Air cushion machine (Blue)	20
3621380	Air cushion machine (Blue)	20
3621488	Air cushion machine (Blue)	20
3621490	Air cushion machine (Blue)	20
3622172	Air cushion machine (Blue)	20
3622183	Air cushion machine (Blue)	20
3620648	Air cushion machine (Blue)	20
3620650	Air cushion machine (Blue)	20
3620800	Air cushion machine (Blue)	20
3620934	Air cushion machine (Blue)	20
3621196	Air cushion machine (Blue)	20
3621256	Air cushion machine (Blue)	20
3619150	Air cushion machine (Blue)	20
3619183	Air cushion machine (Blue)	20
3619709	Air cushion machine (Blue)	20
3619844	Air cushion machine (Blue)	20
3620001	Air cushion machine (Blue)	20
3620205	Air cushion machine (Blue)	20
3618265	Air cushion machine (Blue)	20
3618547	Air cushion machine (Blue)	20
3618816	Air cushion machine (Blue)	20
3618881	Air cushion machine (Blue)	20
3619102	Air cushion machine (Blue)	20
3619128	Air cushion machine (Blue)	20
3616079	Air cushion machine (Blue)	20
3616848	Air cushion machine (Blue)	20
3616852	Air cushion machine (Blue)	20
3617133	Air cushion machine (Blue)	20
3617216	Air cushion machine (Blue)	20
3617415	Air cushion machine (Blue)	20
3614992	Air cushion machine (Blue)	20
3615174	Air cushion machine (Blue)	20
3615240	Air cushion machine (Blue)	20
3615372	Air cushion machine (Blue)	20
3615648	Air cushion machine (Blue)	20
3615781	Air cushion machine (Blue)	20
3613545	Air cushion machine (Blue)	20
3613842	Air cushion machine (Blue)	20
3613848	Air cushion machine (Blue)	20
3614456	Air cushion machine (Blue)	20
3614561	Air cushion machine (Blue)	20
3614723	Air cushion machine (Blue)	20
3613148	Air cushion machine (Blue)	20
3613184	Air cushion machine (Blue)	20
3613188	Air cushion machine (Blue)	20
3613266	Air cushion machine (Blue)	20
3613405	Air cushion machine (Blue)	20
3613472	Air cushion machine (Blue)	20
3612366	Air cushion machine (Blue)	20
3612791	Air cushion machine (Blue)	20
3612859	Air cushion machine (Blue)	20
3612915	Air cushion machine (Blue)	20
3613081	Air cushion machine (Blue)	20
3613126	Air cushion machine (Blue)	20
3612062	Air cushion machine (Blue)	20
3612135	Air cushion machine (Blue)	20
3612218	Air cushion machine (Blue)	20
3612311	Air cushion machine (Blue)	20
3612318	Air cushion machine (Blue)	20
3612348	Air cushion machine (Blue)	20
3611123	Air cushion machine (Blue)	20
3611200	Air cushion machine (Blue)	20
3611257	Air cushion machine (Blue)	20
3611341	Air cushion machine (Blue)	20
3611761	Air cushion machine (Blue)	20
3612051	Air cushion machine (Blue)	20
3609206	Air cushion machine (Blue)	20
3609280	Air cushion machine (Blue)	20
3609869	Air cushion machine (Blue)	20
3609917	Air cushion machine (Blue)	20
3610528	Air cushion machine (Blue)	20
3610551	Air cushion machine (Blue)	20
3608534	Air cushion machine (Blue)	20
3608618	Air cushion machine (Blue)	20
3608637	Air cushion machine (Blue)	20
3608647	Air cushion machine (Blue)	20
3608966	Air cushion machine (Blue)	20
3609177	Air cushion machine (Blue)	20

Observe the query execution plan (or actual plan) of the 2nd execution.

Notice the yellow triangle on the Hash Match operator is gone, which means the query didn't spill and didn't incur in expensive I/O. That difference is also noticeable in the execution time. From the 1st to the 2nd execution, elapsed time dropped from ~43s to ~5s.

Now click on the SELECT node, and look at the MemoryGrantInfo properties. Note the GrantedMemory is now 625 MB (from 1056 KB) and IsMemoryGrantFeedbackAdjusted shows YesAdjusting**. The MGF feature is already learning and adjusting.

On the 3rd execution, the GrantedMemory is still 625 MB, and IsMemoryGrantFeedbackAdjusted shows YesStable. This means the MGF feature found the optimal memory grant that's required to execute the query entirelly in memory.

2nd Execution

3rd Execution

Step 6: Reset the skewed statistics

In [1]:

USE [WideWorldImportersDW]
GO

UPDATE STATISTICS Fact.OrderHistory 
WITH ROWCOUNT = 3702672;
GO

Commands completed successfully.

Commands completed successfully.

Total execution time: 00:00:00.001