title: Why can't I create this sql server full text index?
body: <p>I have a database table with the primary column defined as:</p>
  
  <pre><code>ID bigint identity primary key
  </code></pre>
  
  <p>I also have a text column <code>MiddlePart</code>. I'm trying to create a full text index, like so:</p>
  
  <pre><code>CREATE FULLTEXT INDEX ON domaining.dbo.DomainName
  (
      MiddlePart 
      Language 0X0
  )
  KEY INDEX ID ON domaincatalog
  WITH CHANGE_TRACKING AUTO
  </code></pre>
  
  <p>I get this error:</p>
  
  <p>'ID' is not a valid index to enforce a full-text search key. A full-text search key must be a unique, non-nullable, single-column index which is not offline, is not defined on a non-deterministic or imprecise nonpersisted computed column, does not have a filter, and has maximum size of 900 bytes. Choose another index for the full-text key.</p>
  
  <p>What am I doing wrong?</p>