题目：
Examine this parameter:
NAME TYPE VALUE
------------------------ ------------- ----------------------------------
db_create_file_dest string /u01/app/ oracle/ oradata/prod/
Now examine this statement which executes successfully in an Oracle Database version 18c or later.
CREATETABLESPACE data_olap;
Which two are true about this tablespace and its attributes?
A. The datafile has an Oracle generated name.
B. The initial datafile size is 100MB.
C. The datafile that is created is not auto extensible.
D. The tablespace is created with manual segment space management.
E. The tablespace is a dictionary managed tablespace.
Answer: AB
【解析】
在19c的版本默认情况下，用于永久表空间的Oracle自动管理的数据文件为100 MB，并且可以自动扩展且最大大小不受限制。但是，如果在DATAFILE子句中通过指定SIZE值（且没有AUTOEXTEND子句）覆盖这些默认值，则数据文件不能自动扩展。
【官方手册】
https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/using-oracle-managed-files.html#GUID-D5C4F978-E3C9-4DFF-A076-B0FE75065F32