Functions called in view causing returned columns to be max width

Question

I have some views I need to make as efficient as possible. So the columns in each view are either computed from 2 other tables or a function is used if any other tables need to be queried.
In the view below, the AGMT_TYPE column is obtained by calling the following function.
create or replace FUNCTION "F_GET_AGMT_TYPE" (r_agmt_id lw_agreement_level.agmt_id%type) RETURN VARCHAR2
IS
     vAgmt_Type VARCHAR2(30);
BEGIN
     BEGIN
     select at.AGMT_DESC
into vAgmt_Type
from LW_AGREEMENT_LEVEL a
, LW_CODE_AGMT_TYPE at
where a.AGMT_TYPE_CODE = at.AGMT_TYPE_CODE
and a.agmt_id = r_agmt_id;
RETURN vAgmt_Type;
EXCEPTION
     WHEN NO_DATA_FOUND THEN
          RETURN NULL;
     END;
END;
SQL> desc LW_V_LSE_ACTIVE;
Name Null? Type
POLYGON_GUID VARCHAR2(38)
LSE_LABEL VARCHAR2(20)
LESSOR VARCHAR2(100)
LESSEE VARCHAR2(100)
AGMT_TYPE VARCHAR2(4000)
A_MAP_ACR NUMBER(12,3)
PROSPECT VARCHAR2(4000)
AGMT_ID VARCHAR2(32)
AGMT_NUM VARCHAR2(21)
FILE_KEY NUMBER(18)
The AGMT_TYPE column in its source table is VARCHAR2(32).
Is there any way to enforce this in the resulting view ?

Answer 1

Hi,
If your goal is to make the view as fast as possible, you might be better off leaving the column as VARCHAR2 (4000). Even though it says 4000 characters, only actual data (30 characters or less) is handled.
Here's how to change the view. In your CREATE OR REPLACE VIEW statement, you currently have something like:
SELECT ... F_GET_AGMT_TYPE (id) AS agmt_type ...Change that to
SELECT ... SUBSTR (F_GET_AGMT_TYPE (id), 1, 30) AS agmt_type ...This will proabably make the view easier to use. Do some tests to see if it makes the view faster or slower.