问题：

[多选] What are three benefits of performing data definition language （DDL） statements against a partitioned table with the UPDATE GLOBAL INDEXES clause？（）

A . Global indexes are rebuilt automatically at the end of the DDL operation thereby avoiding problems with the UNUSABLE status. 
B . You do not have to search for invalid global indexes after the DDL command completes and rebuild them individually. 
C . Global indexes are maintained during the operation of the DDL command and therefore can be used by any concurrent query. 
D . Global indexes remain intact and available for use by data manipulation language （DML） statements even for sessions that have not enabled the skipping of unusable indexes.