title: SQL Server Index Which should be clustered?
body: <p>I have a number of indexes on some tables, they are all similar and I want to know if the Clustered Index is on the correct column.  Here are the stats from the two most active indexes:</p>
  
  <pre><code>Nonclustered
  I3_Identity (bigint)
  rows: 193,781
  pages: 3821
  MB: 29.85
  user seeks: 463,355
  user_scans: 784
  user_lookups: 0
  updates: 256,516
  
  Clustered Primary Key
  I3_RowId (varchar(80))
  rows: 193,781
  pages: 24,289
  MB: 189.76
  user_seeks: 2,473,413
  user_scans: 958
  user_lookups: 463,693
  updates: 2,669,261
  </code></pre>
  
  <p>As you can see, the PK is being seeked often, but all the seeks for the i3_identity column are doing key lookups to this PK as well, so am I really benefiting from the index on I3_Identity much at all?  Should I change to using the I3_Identity as the clustered?  This could have a huge impact as this table structure is repeated about 10000 times where I work, so any help would be appreciated.</p>