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

ORA-39726:

 unsupported add/drop column operation on compressed tables

問題現象 :

Basic compression 下，增加字段時不能指定default ，否則報錯 ORA-39726；

問題重現：
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

問題原因 :

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

解決方案：

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，但是很多情況下業務邏輯是不允許的；

ALTER TABLE t1 ADD UPDATE_TIME DATE;

--- 將表壓縮級別 basic 改成 oltp 后可以正常添加字段；
--- 對現有的數據不壓縮，對以后產生的數據生效，數據量越大，速度越慢，測試 1 億條數據，耗時 30 秒；

SQL> alter table t1 compress for oltp;    
---- 對現有的和以后的數據都生效，數據量越大，速度越慢，并且會產生排它鎖，生產環境慎用；

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，刪除字段也會有這個問題

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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