20180427-ORA-39726:unsupported add/drop column operation on compressed tables

问题现象 :

Basic compression 下，增加字段时不能指定default ，否则报错 ORA-39726；

问题重现：

SQL> conn chenjch/a
SQL> create table t1(id number(10) not null) compress;
SQL> insert into t1 values(1);
SQL> commit;
SQL> ALTER TABLE t1 ADD UPDATE_TIME DATE DEFAULT SYSDATE NOT NULL ;
ALTER TABLE t1 ADD UPDATE_TIME DATE DEFAULT SYSDATE NOT NULL
                   *
ERROR at line 1:
ORA-39726: unsupported add/drop column operation on compressed tables

问题原因 :

https://docs.oracle.com/cd/E11882_01/server.112/e25494/tables.htm#ADMIN11630

解决方案：

SQL> SELECT table_name, compression, compress_for FROM user_tables where table_name='T1';
TABLE_NAME COMPRESS COMPRESS_FOR
---------- -------- ------------------------------
T1         ENABLED   BASIC

— 去掉 default 后可以正常添加列，但是很多情况下业务逻辑是不允许的；

ALTER TABLE t1 ADD UPDATE_TIME DATE;

— 将表压缩级别 basic 改成 oltp 后可以正常添加字段；
— 对现有的数据不压缩，对以后产生的数据生效，数据量越大，速度越慢，测试 1 亿条数据，耗时 30 秒；

SQL> alter table t1 compress for oltp;

---- 对现有的和以后的数据都生效，数据量越大，速度越慢，并且会产生排它锁，生产环境慎用；

sql> Alter table t1 move compress for oltp;  
SQL>  SELECT table_name, compression, compress_for FROM user_tables where table_name='T1';
TABLE_NAME COMPRESS COMPRESS_FOR
---------- -------- ------------------------------
T1         ENABLED   ADVANCED

SQL> ALTER TABLE t1 ADD UPDATE_TIME DATE DEFAULT SYSDATE NOT NULL ;
Table altered.

— 字段添加成功后也可以在改回 basic;

SQL> alter table t1 compress;
Table altered.

SQL> SELECT table_name, compression, compress_for FROM user_tables where table_name='T1';
TABLE_NAME COMPRESS COMPRESS_FOR
---------- -------- ------------------------------
T1         ENABLED  BASIC

同理，删除字段也会有这个问题

SQL> ALTER TABLE t1 drop column  UPDATE_TIME;
ALTER TABLE t1 drop column  UPDATE_TIME
                            *
ERROR at line 1:
ORA-39726: unsupported add/drop column operation on compressed tables

SQL> ALTER TABLE t1 SET UNUSED COLUMN UPDATE_TIME;
Table altered.

SQL> ALTER TABLE t1 DROP UNUSED COLUMNS;
ALTER TABLE t1 DROP UNUSED COLUMNS
*
ERROR at line 1:
ORA-39726: unsupported add/drop column operation on compressed tables

SQL> alter table t1 compress for oltp;
Table altered.

SQL> ALTER TABLE t1 DROP UNUSED COLUMNS;
Table altered.

SQL> alter table t1 compress;
Table altered.

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