Traceflag 2792 enables the fix for CR 475139-1 to sleep on the DES_CLONED_STATE of the DES.
CR 475139 description:
Trace Flag 2792 introduced to cause processes to be blocked while attempting to access a table undergoing REORG REBUILD rather than abort with an 8233 error.
Error 8233 example:
Msg 8233, Level 16, State 1: Server 't1501', Line 1: An alter table or reorg operation is in progress on the object 'r' in database 'test'. Please retry your query later.
Why you would use this flag:
You would prefer for processes to wait until the alter table or reorg operations complete, and then proceed normally, much like selects would be blocked by a process holding an exclusive lock.