LINQ To SQL Samples - Object Identity

Object Caching - 1

This sample demonstrates how, upon executing the same query twice, you will receive a reference to the same object in memory each time.

Public Sub LinqToSqlObjectIdentity01()
    Dim cust1 As Customer = db.Customers.First(Function(c) c.CustomerID = "BONAP")
    Dim cust2 As Customer = (From c In db.Customers _
        Where c.CustomerID = "BONAP" _
        Select c).First()

    Console.WriteLine("cust1 and cust2 refer to the same object in memory: {0}", _
        Object.ReferenceEquals(cust1, cust2))
End Sub

Result:
cust1 and cust2 refer to the same object in memory: True

Object Caching - 2

This sample demonstrates how, upon executing different queries that return the same row from the database, you will receive a reference to the same object in memory each time.

Public Sub LinqToSqlObjectIdentity02()
    Dim cust1 As Customer = db.Customers.First(Function(c) c.CustomerID = "BONAP")
    Dim cust2 As Customer = (From o In db.Orders _
        Where o.Customer.CustomerID = "BONAP" _
        Select o).First().Customer

    Console.WriteLine("cust1 and cust2 refer to the same object in memory: {0}", _
        Object.ReferenceEquals(cust1, cust2))
End Sub

Result:
cust1 and cust2 refer to the same object in memory: True