How to wrap a view in oracle

Question

Does any one know how to wrap a view in Oracle, I know it is not possible, yet. Are there any third party software to wrap the logic in the view.
Thanks,
Sanjay

Answer 1

Your best bet is to write a view that queries the source tables and contains any necessary business logic
CREATE VIEW VBASE AS SELECT A.COLUMN_A FROM TABLE_1 A, TABLE_2 B, TABLE_3 C WHERE A.ID = B.ID AND B.ID = C.ID;
create a view for exposure to the user that queries the base view.
CREATE VIEW VSECURE AS SELECT COLUMN_B FROM VBASE;
and grant privileges to VSECURE.
GRANT SELECT ON VSECURE TO SECURE_USER;
This will allow the user to see, query, and describe VSECURE without seeing the definition for VBASE.
The advantage of the this approach is that the query engine can still push predicates down into the base view to optimize the performance or the query where as this is limited with the pipeline function and can become a tuning headache.
eg.
SQL> -----------------------------------------
SQL> -- create some tables
SQL> -----------------------------------------
SQL> CREATE TABLE table_1(ID NUMBER, MESSAGE VARCHAR2(100))
Table created.
SQL> CREATE TABLE table_2(ID NUMBER, message2 VARCHAR2(100))
Table created.
SQL> CREATE TABLE table_3(ID NUMBER, message3 VARCHAR2(100))
Table created.
SQL> -----------------------------------------
SQL> -- populate tables with some data
SQL> -----------------------------------------
SQL> INSERT INTO table_1
SELECT ROWNUM,
CASE
WHEN MOD ( ROWNUM, 50 ) = 0 THEN 'HELLO there joe'
ELSE 'goodbye joe'
END
FROM DUAL
CONNECT BY LEVEL < 1000000
999999 rows created.
SQL> INSERT INTO table_2
SELECT ROWNUM,
CASE
WHEN MOD ( ROWNUM, 50 ) = 0 THEN 'how are you joe'
ELSE 'good to see you joe'
END
FROM DUAL
CONNECT BY LEVEL < 1000000
999999 rows created.
SQL> INSERT INTO table_3
SELECT ROWNUM,
CASE
WHEN MOD ( ROWNUM, 50 ) = 0 THEN 'just some data'
ELSE 'other stuff'
END
FROM DUAL
CONNECT BY LEVEL < 1000000
999999 rows created.
SQL> -----------------------------------------
SQL> --create base view
SQL> -----------------------------------------
SQL> CREATE OR REPLACE VIEW vbase AS
SELECT a.MESSAGE,
c.message3
FROM table_1 a,
table_2 b,
table_3 c
WHERE a.ID = b.ID
AND b.ID = c.ID
View created.
SQL> -----------------------------------------
SQL> --create secure view using base view
SQL> -----------------------------------------
SQL> CREATE OR REPLACE VIEW vsecure AS
SELECT MESSAGE,
message3
FROM vbase
View created.
SQL> -----------------------------------------
SQL> -- create row type for pipeline function
SQL> -----------------------------------------
SQL> CREATE OR REPLACE TYPE vbase_row
AS OBJECT
message varchar2(100),
message3 varchar2(100)
Type created.
SQL> -----------------------------------------
SQL> -- create table type for pipeline function
SQL> -----------------------------------------
SQL> CREATE OR REPLACE TYPE vbase_table
AS TABLE OF vbase_row;
Type created.
SQL> -----------------------------------------
SQL> -- create package
SQL> -----------------------------------------
SQL> CREATE OR REPLACE PACKAGE pkg_getdata AS
FUNCTION f_get_vbase
RETURN vbase_table PIPELINED;
END;
Package created.
SQL> -----------------------------------------
SQL> -- create package body with pipeline function using same query as vbase
SQL> -----------------------------------------
SQL> CREATE OR REPLACE PACKAGE BODY pkg_getdata AS
FUNCTION f_get_vbase
RETURN vbase_table PIPELINED IS
CURSOR cur IS
SELECT a.MESSAGE,
c.message3
FROM table_1 a,
table_2 b,
table_3 c
WHERE a.ID = b.ID
AND b.ID = c.ID;
BEGIN
FOR rec IN cur
LOOP
PIPE ROW ( vbase_row ( rec.MESSAGE, rec.message3 ) );
END LOOP;
END;
END pkg_getdata;
Package body created.
SQL> -----------------------------------------
SQL> -- create secure view using pipeline function
SQL> -----------------------------------------
SQL> CREATE or replace VIEW vsecure_with_pipe AS
SELECT *
FROM TABLE ( pkg_getdata.f_get_vbase ( ) )
View created.
SQL> -----------------------------------------
SQL> -- this would grant select on the 2 views, one with nested view, one with nested pipeline function
SQL> -----------------------------------------
SQL> GRANT SELECT ON vsecure TO test_user
Grant complete.
SQL> GRANT SELECT ON vsecure_with_pipe TO test_user
Grant complete.
SQL> explain plan for
SELECT *
FROM vsecure
WHERE MESSAGE LIKE 'HELLO%'
Explain complete.
SQL> SELECT *
FROM TABLE ( DBMS_XPLAN.display ( ) )
PLAN_TABLE_OUTPUT
Plan hash value: 3905984671
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 16939 | 2365K| | 3098 (3)| 00:00:54 |
|* 1 | HASH JOIN | | 16939 | 2365K| 2120K| 3098 (3)| 00:00:54 |
|* 2 | HASH JOIN | | 24103 | 1835K| | 993 (5)| 00:00:18 |
|* 3 | TABLE ACCESS FULL| TABLE_1 | 24102 | 1529K| | 426 (5)| 00:00:08 |
| 4 | TABLE ACCESS FULL| TABLE_2 | 1175K| 14M| | 559 (3)| 00:00:10 |
| 5 | TABLE ACCESS FULL | TABLE_3 | 826K| 51M| | 415 (3)| 00:00:08 |
Predicate Information (identified by operation id):
1 - access("B"."ID"="C"."ID")
2 - access("A"."ID"="B"."ID")
3 - filter("A"."MESSAGE" LIKE 'HELLO%')
Note
PLAN_TABLE_OUTPUT
- dynamic sampling used for this statement
23 rows selected.
SQL> -----------------------------------------
SQL> -- note that the explain plan shows the predicate pushed down into the base view.
SQL> -----------------------------------------
SQL> explain plan for
SELECT count(*)
FROM vsecure_with_pipe
WHERE MESSAGE LIKE 'HELLO%'
Explain complete.
SQL> SELECT *
FROM TABLE ( DBMS_XPLAN.display ( ) )
PLAN_TABLE_OUTPUT
Plan hash value: 19045890
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
| 0 | SELECT STATEMENT | | 1 | 2 | 15 (0)| 00:00:01 |
| 1 | SORT AGGREGATE | | 1 | 2 | | |
|* 2 | COLLECTION ITERATOR PICKLER FETCH| F_GET_VBASE | | | | |
Predicate Information (identified by operation id):
2 - filter(VALUE(KOKBF$) LIKE 'HELLO%')
14 rows selected.
SQL> -----------------------------------------
SQL> -- note that the filter is applied on the results of the pipeline function
SQL> -----------------------------------------
SQL> set timing on
SQL> SELECT count(*)
FROM vsecure
WHERE MESSAGE LIKE 'HELLO%'
COUNT(*)
19999
1 row selected.
Elapsed: 00:00:01.42
SQL> SELECT count(*)
FROM vsecure_with_pipe
WHERE MESSAGE LIKE 'HELLO%'
COUNT(*)
19999
1 row selected.
Elapsed: 00:00:04.11
SQL> -----------------------------------------
SQL> -- note the difference in the execution times.
SQL> -----------------------------------------