When attempting to drop a non-clustered index using the online option such as
DROP INDEX [IX_MYINDEX] ON [dbo].[myTable] WITH ( ONLINE = ON ), I receive the following error message.
Msg 3745, Level 16, State 1, Line 16 Only a clustered index can be dropped online.
The SQL Server documentation clearly states:
The ONLINE option can only be specified when you drop clustered indexes.
But can someone please explain to me why this is the case? In my experience, you would be much more likely to drop a non-clustered index than a clustered index, since the clustered index in most cases is also your primary key.