A. Compression can be enabled at the table,tablespace,or partition level for direct loads only.
B. Compression can be enabled only at the table level for both direct loadsand conventional DML.
C. Compression can be enabled at the table,tablespace,or partition level for conventional DML only.
D. Compression can be enabled at the table,tablespace,or partition level for both direct loads and conventional DML.
答案：（D）
解析：
You can specify compression for a tablespace,a table,or a partition.If specified at the tablespace level,then all tables created in that tablespace are compressed by default.
Compression has a cost in CPU overhead for data loading and DML.