Hints (Transact-SQL) - Join
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Join hints specify that the query optimizer enforce a join strategy between two tables in SQL Server. For general information about joins and join syntax, see FROM (Transact-SQL).
Caution
Because the SQL Server query optimizer typically selects the best execution plan for a query, we recommend that hints be used only as a last resort by experienced developers and database administrators.
Applies to
Transact-SQL syntax conventions
Syntax
<join_hint> ::=
{ LOOP | HASH | MERGE | REMOTE }
Note
To view Transact-SQL syntax for SQL Server 2014 and earlier, see Previous versions documentation.
Arguments
LOOP | HASH | MERGE
Specifies that the join in the query should use looping, hashing, or merging. Using LOOP |HASH | MERGE JOIN enforces a particular join between two tables. LOOP cannot be specified together with RIGHT or FULL as a join type. For more information, see Joins.
REMOTE
Specifies that the join operation is performed on the site of the right table. This is useful when the left table is a local table and the right table is a remote table. REMOTE should be used only when the left table has fewer rows than the right table.
If the right table is local, the join is performed locally. If both tables are remote but from different data sources, REMOTE causes the join to be performed on the site of the right table. If both tables are remote tables from the same data source, REMOTE is not required.
REMOTE cannot be used when one of the values being compared in the join predicate is cast to a different collation using the COLLATE clause.
REMOTE can be used only for INNER JOIN operations.
Remarks
Join hints are specified in the FROM clause of a query. Join hints enforce a join strategy between two tables. If a join hint is specified for any two tables, the query optimizer automatically enforces the join order for all joined tables in the query, based on the position of the ON keywords. When a CROSS JOIN is used without the ON clause, parentheses can be used to indicate the join order.
Examples
A. Using HASH
The following example specifies that the JOIN operation in the query is performed by a HASH join. The example uses the AdventureWorks2022 database.
SELECT p.Name, pr.ProductReviewID
FROM Production.Product AS p
LEFT OUTER HASH JOIN Production.ProductReview AS pr
ON p.ProductID = pr.ProductID
ORDER BY ProductReviewID DESC;
B. Using LOOP
The following example specifies that the JOIN operation in the query is performed by a LOOP join. The example uses the AdventureWorks2022 database.
DELETE FROM Sales.SalesPersonQuotaHistory
FROM Sales.SalesPersonQuotaHistory AS spqh
INNER LOOP JOIN Sales.SalesPerson AS sp
ON spqh.SalesPersonID = sp.SalesPersonID
WHERE sp.SalesYTD > 2500000.00;
GO
C. Using MERGE
The following example specifies that the JOIN operation in the query is performed by a MERGE join. The example uses the AdventureWorks2022 database.
SELECT poh.PurchaseOrderID, poh.OrderDate, pod.ProductID, pod.DueDate, poh.VendorID
FROM Purchasing.PurchaseOrderHeader AS poh
INNER MERGE JOIN Purchasing.PurchaseOrderDetail AS pod
ON poh.PurchaseOrderID = pod.PurchaseOrderID;
GO