title: Insert strategy for tables with one-to-one relationships in Teradata
body: <p>In our data model, which is derived from the Teradata industry models, we observe a common pattern, where the superclass and subclass relationships in the logical data model are transformed into one-to-one relationships between the parent and the child table. </p>
  
  <p>I know you can roll-up or roll-down the attributes to end up with a single table but we are not using this option overall. At the end what we have is a model like this:</p>
  
  <p><a href="https://i.stack.imgur.com/cvusc.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cvusc.jpg" alt="enter image description here"></a></p>
  
  <p>Where City Id references a Geographical Area Id.</p>
  
  <p>I am struggling with a good strategy to load the records in these tables.</p>
  
  <p><strong>Option 1:</strong> I could select the max(Geographical Area Id) and calculate the next Ids for a batch insert and reuse them for the City Table.</p>
  
  <p><strong>Option 2:</strong> I could use an Identity column in the Geographical Area Table and retrieve it after I insert every record in order to use it for the City table.</p>
  
  <p>Any other options?</p>
  
  <p>I need to assess the solution in terms of performance, reliability and maintenance. </p>
  
  <p>Any comment will be appreciated.</p>
  
  <p>Kind regards, </p>
  
  <p>Paul </p>