When you bulk load data into a clustered columnstore index under memory pressure in Microsoft SQL Server 2016, all the data is inserted into the deltastores, and the Log Optimization can't be used. Therefore, the operation takes a longer time to be completed. If SQL Server restarts in that situation, it may take a long time for SQL Server to recover the database after the restart.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Article ID: 3174073 - Last Review: Jul 25, 2016 - Revision: 1