在oracle中，这个参数用于指定Oracle数据库服务器创建数据文件的缺省路径。

SQL> set linesize 1000
SQL> set pagesize 1000
SQL> show parameter db_create_file_dest;

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
db_create_file_dest                  string

SQL> alter system set db_create_file_dest='/oradata' scope=both;

System altered.

[root@db02 oradata]# ll
total 3626536
-rw-r----- 1 oracle oinstall 1073750016 Apr 26 13:05 APPRPTFASDLS_SCHE_DATA_TBS.dbf
-rw-r----- 1 oracle oinstall  157294592 Apr 26 08:29 APPRPTMFGMMCS_SCHE_DATA_TBS.dbf
-rw-r----- 1 oracle oinstall 2147491840 Apr 26 08:29 bftbs01.dbf
drwxr-xr-x 2 oracle oinstall         50 Apr  5 13:48 dumpfiles
-rw-r----- 1 oracle oinstall  230170624 Apr 26 08:29 hbhetbs01.dbf
-rw-r----- 1 oracle oinstall  104865792 Apr 26 08:29 rmants.dbf

SQL> create tablespace data_olap;

Tablespace created.

[root@db02 oradata]# ll
total 3626536
-rw-r----- 1 oracle oinstall 1073750016 Apr 26 13:05 APPRPTFASDLS_SCHE_DATA_TBS.dbf
-rw-r----- 1 oracle oinstall  157294592 Apr 26 08:29 APPRPTMFGMMCS_SCHE_DATA_TBS.dbf
-rw-r----- 1 oracle oinstall 2147491840 Apr 26 08:29 bftbs01.dbf
drwxr-xr-x 2 oracle oinstall         50 Apr  5 13:48 dumpfiles
-rw-r----- 1 oracle oinstall  230170624 Apr 26 08:29 hbhetbs01.dbf
drwxr-x--- 3 oracle oinstall         22 Apr 26 15:46 ORCL
-rw-r----- 1 oracle oinstall  104865792 Apr 26 08:29 rmants.dbf
[root@db02 oradata]# cd ORCL/
[root@db02 ORCL]# ll
total 0
drwxr-x--- 2 oracle oinstall 42 Apr 26 15:46 datafile
[root@db02 ORCL]# cd datafile/
[root@db02 datafile]# ll
total 102408
-rw-r----- 1 oracle oinstall 104865792 Apr 26 15:46 o1_mf_data_ola_k6h8tcwx_.dbf
[root@db02 datafile]# du -sm o1_mf_data_ola_k6h8tcwx_.dbf 
101     o1_mf_data_ola_k6h8tcwx_.dbf

参数解释：
DB_CREATE_FILE_DEST specifies the default location for Oracle-managed datafiles. This
location is also used as the default location for Oracle-managed control files and online
redo logs if none of the DB_CREATE_ONLINE_LOG_DEST_ n initialization parameters are
specified