I've come across an issue where large numbers of statistics (some user created, some auto created) in a database have no Updated value when using the SHOW_STATS system function, but do exist when I search for them in sys.stats. These statistics sometimes belong to non-clustered indexes on the table, and sometimes don't (i.e., they just belong to the columns). Additionally, if I run DBCC SHOW_STATISTCS no data is returned for these particular stats. They exist, but have no zero statistical data and I can't tell if they were ever updated.
Couple question:
1) How does this happen?
2) Is this an indication of a problem (i.e., are these "orphaned statistics")?
3) Does this suggest they should be dropped since they clearly serve no purpose.
Thanks!