From what I understand about index fragmentation, this should not be possible. The cases I have found in my databases are non-clustered.
Example:
ALTER TABLE [dbo].[ClaimLineInstitutional] ADD CONSTRAINT [PK_ClaimLineInsitutional]
PRIMARY KEY NONCLUSTERED
(
[ClaimLineInstitutionalID] ASC
)WITH (PAD_INDEX = ON, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF,
IGNORE_DUP_KEY = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON,
FILLFACTOR = 100) ON [PRIMARY]
Update:
I am querying dm_db_index_physical_stats.avg_fragmentation_in_percent, so I believe it is physical fragmentation I am seeing.
Best Answer
Updates on data already there causes rows to be moved and forward pointers added
In this test, we can get 65% fragmentation on 115k densely packed rows
Edit, sorry, browser trouble
If you change the middle replicate to 2000 you get <5% at the end. This happens because there is free space from moved rows in the first update