Mala Mahadevan continues a series on graph tables in SQL Server:
I have highlighted in red what SQL Server adds to the table – the two system columns – graph id, which is bigint, and node id, which is nvarchar and stores json, and the unique index to help with queries.
We can also see from constraint type that this table is similar to other relational tables – it can be enabled for replication and can have related delete or update actions defined on it if need be.
This post gives a bit more insight into how graph tables work in SQL Server under the covers.