I am trying to create a non clustered index on a table which is around 500GB. The table already has a clustered index on it. Since we do not want other transaction to be blocked we tried using
ONLINE=ON, however at the beginning of the index build it blocked other OLTP transactions.
When I checked what locks were being held I noticed exclusive table lock on the table and other transactions are getting blocked by this.
I look at Guidelines for Online Index Operations for exclusions and its not applicable for this table.
Any idea why this is happening?