由于UNION，视图和表的列大小不匹配

Question

我已经使用联合的CVAS创建了View：

CREATE
OR REPLACE VIEW SAMPLEVIEW AS
SELECT
  PT.CREDITPARTYACCOUNT AS PT_CREDITPARTYACCOUNT,
  PT.DEBITPARTYACCOUNT AS PT_DEBITPARTYACCOUNT,
...
...
FROM
  accountingevent AE
  LEFT OUTER JOIN paymenttransaction PT ON (
    AE.PAYMENTTRANSACTIONKEY = PT.PAYMENTTRANSACTIONKEY
  )
  OR (
    AE.PAYMENTINSTRUCTIONKEY = PT.INCOMINGINSTRUCTIONKEY
  )
WHERE
  ...
UNION ALL
SELECT
  PT.CREDITPARTYACCOUNT AS PT_CREDITPARTYACCOUNT,
  PT.DEBITPARTYACCOUNT AS PT_DEBITPARTYACCOUNT,
...
...
FROM
  accountingevent AE
  LEFT OUTER JOIN paymenttransaction PT ON (
    AE.PAYMENTTRANSACTIONKEY = PT.PAYMENTTRANSACTIONKEY
  )
WHERE
    ...
ORDER BY 1;

结果

DESC SAMPLEVIEW;
PT_CREDITPARTYACCOUNT   VARCHAR2(1024 CHAR)
PT_DEBITPARTYACCOUNT    VARCHAR2(1024 CHAR)
...
...

AND

DESC PAYMENTTRANSACTION;
CREDITPARTYACCOUNT  VARCHAR2(256 CHAR)
DEBITPARTYACCOUNT   VARCHAR2(256 CHAR)
...

我得到的数据大小是4倍表列大小的大小。如果我们删除UNION ALL并使用单个CVAS，则表和视图中的大小将相等。该视图和表是大型脚本的一部分，因此脚本中的某些内容已关闭，导致此行为。此奇怪的行为仅在char和varchar2数据类型中可见。我还检查了以下查询的结果：

select * from NLS_DATABASE_PARAMETERS where parameter='NLS_CHARACTERSET';
NLS_CHARACTERSET    AL32UTF8

请指导我有关可能导致此问题的错误之处。

谢谢

Answer 1

您正在测试哪个版本？这是我在数据库（20.2）上获得的信息：

SQL> desc tukc
Name        Null? Type               
----------- ----- ------------------ 
OBJECT_NAME       VARCHAR2(128 CHAR) 
OBJECT_ID         NUMBER             
SQL> 
SQL> create or replace view tv as
  2  select t.object_name
  3  from tukc t join all_objects o on (t.object_id=o.object_id)
  4  union all
  5  select t.object_name
  6  from tukc t join all_objects o on (t.object_id=o.object_id)
  7  ;

View TV created.

SQL> desc tv
Name        Null? Type               
----------- ----- ------------------ 
OBJECT_NAME       VARCHAR2(128 CHAR)