[oracle@rhel63single ~]$ sqlplus scott/aaaaaa
SQL*Plus: Release 11.2.0.4.0 Production on Sat Apr 8 02:54:40 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options
SQL> show parameter defer
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
deferred_segment_creation boolean TRUE
SQL> create table testa(reg_id number,reg_name varchar2(200)) segment creation immediate;
Table created.
SQL> create table testb(reg_id number,reg_name varchar2(200)) ;
Table created.
SQL> create table testc(reg_id number,reg_name varchar2(200)) segment creation deferred;
Table created.
SQL> select segment_name from user_segments where segment_name in( 'TESTA','TESTB','TESTC');
SEGMENT_NAME
--------------------------------------------------------------------------------
TESTA
SQL> select segment_name from user_extents where segment_name in( 'TESTA','TESTB','TESTC');
SEGMENT_NAME
--------------------------------------------------------------------------------
TESTA
SQL>
总结:
1.create table的参数 segment creation immediate 的优先级高于数据库初始化参数deferred_segment_creation
2.create table的参数 segment creation immediate 的反义参数是segment creation deferred
