基本的表压缩和高级压缩之间的区别，
摘录自mos文章Difference Between Basic Table Compression And Advanced Compression (Doc ID 1548187.1)
适用于：
Oracle Database - Enterprise Edition - Version 10.2.0.5 and later
Information in this document applies to any platform.
目标：
What is the difference between Basic Table Compression in 10g and Advanced Table Compression in 11gR2?
方法：
user_tables 或者dba_tables视图中的COMPRESS_FOR列，在11.2和 11.1版本中，返回的值是不同的。
在11.2中，该列的返回值是 BASIC or OLTP
在11.1中，该列的返回值是 DIRECT LOAD ONLY and FOR ALL OPERATIONS
使用alter table...move...compress, alter index...rebuild...compress 命令，此时是使用的基本的压缩，除非使用高级压缩的授权。
基本的压缩仅仅在如下情况下才有效：
direct path operations--比如 insert /*+APPEND*/, alter table t move, create table as select, sqlldr direct=y
基本的压缩并不阻止你使用正常的nsert/update/delete语句。----这就是说：这些dml语句会产生（result in）一些非压缩数据。
一个表中可以存在压缩的blocks和没压缩的blocks--这是能正常工作的。
There are restrictions as to what you can do with a basic compressed table as far as dropping columns and the like.
Restrictions on Table Compression Table compression is subject to the following restrictions:
COMPRESS FOR OLTP and COMPRESS BASIC are not supported for tables with more than 255 columns.
As "COMPRESS FOR OLTP" is part of Advanced compression, the restriction holds good for it as well.
You need separate license to use 11g Advanced Compression.
For more information on Advanced Compression, see the OTN site.
