What locks are taken during statistic operations in SQL Server? What locks are taken during the various statistic operations below in SQL Server assuming the default options of auto create stats and auto update stats are set to true?


Automatic creation of a statistic object
Automatic update of a statistic object
Manual creation of a statistic object
Manual update of a statistic object


Is there any difference in the locks taken in scenarios 1 &amp; 2 above when statistics are set to update asynchronously?
AFAIK, the only real X lock that is taken is on the 'statistics resource'.  The rest of the locks can be read around and don't block.


  That is a resource that only statistics operations care about. It
  exists to limit the number of stats operations in progress on a single
  table to one at a time. Auto-statistics operations do not wait for it
  but just abort if they cannot get it. Manual statistics operations do
  wait for the resource.


https://connect.microsoft.com/SQLServer/feedback/details/174619/update-statistics-holding-exclusive-lock-and-blocking