Unfortunately this is not the same as a clustered index as seen in other db&#x27;s like MS SQL server.<p>With a true clustered index, the table IS the index, this saves space and time by not having to maintain a secondary index and then looking up the result in the table. This can be very important especially with large datasets.<p>Really wish true clustered indexes where implemented in PG. Kind of odd the article doesn&#x27;t mention this while starting out explaining clustered vs non-clustered.