title: Benefit of combining a clustered columnstore index and a nonclustered columnstore index?
body: <p>I ran into a question about <strong>indexing a large fact table in a data warehouse</strong> asking to implement <strong>two</strong> indexes in order to optimize performance and the answer suggested to create:</p>
  
  <ul>
  <li>a clustered <strong>columnstore</strong> index (CCI)</li>
  <li>and a nonclustered <strong>columnstore</strong> index (NCCI) on part of the columns</li>
  </ul>
  
  <p>As a CCI includes all the table's columns, I would have thought that there would be no point in combining two columnstore indexes (one clustered and one nonclustered) and rather go for :</p>
  
  <ul>
  <li>a clustered <strong>columnstore</strong> index (CCI)</li>
  <li>and a nonclustered <strong>rowstore</strong> index on part of the columns</li>
  </ul>
  
  <p>(see <a href="https://docs.microsoft.com/en-us/sql/relational-databases/indexes/columnstore-indexes-design-guidance?view=sql-server-ver15" rel="nofollow noreferrer">microsoft documentation on columnstore index design guidance</a>)</p>
  
  <p><strong>What would be the benefit, if there is any, of combining two columnstore indexes (one clustered and one non clustered) on a large fact table</strong> in a SQL Server database / data warehouse <strong>?</strong></p>
  
  <p>The question that triggered my question can be found <a href="https://www.examtopics.com/exams/microsoft/70-767/view/18/" rel="nofollow noreferrer">on this page</a>, question 70.
  I don't know if I am missing something or if their solution is inaccurate.</p>
  
  <p>If anyone could help me out, it would be great!</p>