SQL SERVER – Error Msg 10778, Level 16 with InMemory OLTP

SQL Server 2016 brought several innovations. One of the most anticipated feature additions was the ability to define foreign keys with InMemory tables. I wrote about this feature earlier on blog at: SQL SERVER 2016 – InMemory OLTP support for Foreign Key.

Though this was a great addition, I always felt there were restrictions still to know and understand. The twist to the previous blog was to create a Foreign key on a standard disk based table. I went about using the below script for the same.

CREATE TABLE Products
(
ProductID INT CONSTRAINT pk_products_pid PRIMARY KEY NONCLUSTERED HASH (ProductID) WITH (BUCKET_COUNT = 10000),
ProductName VARCHAR(25)
 ) WITH ( MEMORY_OPTIMIZED = ON, DURABILITY = SCHEMA_AND_DATA);
GO
CREATE TABLE ProductSales
(
SalesID INT CONSTRAINT pk_productSales_sid PRIMARY KEY,
ProductID INT CONSTRAINT fk_productSales_pid FOREIGN KEY REFERENCES Products(ProductID),
SalesPerson VARCHAR(25)
 )
GO

I was pleasantly surprised that an error message popped up. I am showing the same below:

Msg 10778, Level 16, State 0, Line 1
Foreign key relationships between memory optimized tables and non-memory optimized tables are not supported.

This was a great learning that was worth a share via blogs. Though the foreign key addition was lesser known to many, even more lesser known is the fact that it cannot be across disk based tables and in-memory tables. Do let me know if you were aware of this?

Reference: Pinal Dave (https://blog.sqlauthority.com)