I am tuning fill factors, and my brain is slightly fried, so I wonder if someone can confirm this: If a table is clustered on an identity column, then all the inserts will happen at the "end, " and no update will ever change the location of a record (identity cannot be updated). So the best fill factor would be 0 (or 100), so all pages are full. On the other hand, an index without that condition, on a table that undergoes inserts / updates, would want to have some space on each data page to accomodate changes throughout the data -- fill factor 90 or 85. Am I correct? OR In the case of a table clustered on identity, might the size of a row change when, for example, a VARCHAR column is updated, causing a full data page to split because of the larger row?