Quesion about dbms_advanced_rewrite ???

Question

SCOTT@oracle10g>alter session set nls_language=american;
Session altered.
SCOTT@oracle10g>create table tt1 as select * from user_objects;
Table created.
SCOTT@oracle10g>create table tt2 as select * from dba_objects where owner='SYSTEM';
Table created.
SCOTT@oracle10g>exec dbms_stats.gather_table_stats(user,'TT1');
PL/SQL procedure successfully completed.
SCOTT@oracle10g>exec dbms_stats.gather_table_stats(user,'TT2');
PL/SQL procedure successfully completed.
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2);
Execution Plan
Plan hash value: 720405399
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |    20 |  1600 |    45   (0)| 00:00:01 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| TT1  |    21 |  1680 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |     1 |     5 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( NOT EXISTS (SELECT /*+ */ 0 FROM "TT2" "TT2" WHERE
              LNNVL("OBJECT_ID"<>:B1)))
   3 - filter(LNNVL("OBJECT_ID"<>:B1))
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2
  2  where object_id is not null) and object_id is not null;
Execution Plan
Plan hash value: 2268948225
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |     2 |   170 |     8  (13)| 00:00:01 |
|*  1 |  HASH JOIN ANTI    |      |     2 |   170 |     8  (13)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL| TT1  |    21 |  1680 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |   469 |  2345 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - access("OBJECT_ID"="OBJECT_ID")
   2 - filter("OBJECT_ID" IS NOT NULL)
   3 - filter("OBJECT_ID" IS NOT NULL)
SCOTT@oracle10g>begin
  2    sys.dbms_advanced_rewrite.DECLARE_REWRITE_EQUIVALENCE('TEST','select * from tt1 where object_
id not in (select object_id from tt2)','select * from tt1 where object_id not in (select object_id f
rom tt2 where object_id is not null) and object_id is not null',false,'text_match');
  3  end;
  4  /
PL/SQL procedure successfully completed.
SCOTT@oracle10g>alter session set query_rewrite_integrity=trusted;
Session altered.
SCOTT@oracle10g>set autot trace exp
SCOTT@oracle10g>alter session set sql_trace=true;
Session altered.
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2);
Execution Plan
Plan hash value: 2268948225
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |     2 |   170 |     8  (13)| 00:00:01 |
|*  1 |  HASH JOIN ANTI    |      |     2 |   170 |     8  (13)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL| TT1  |    21 |  1680 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |   469 |  2345 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - access("OBJECT_ID"="OBJECT_ID")
   2 - filter("OBJECT_ID" IS NOT NULL)
   3 - filter("OBJECT_ID" IS NOT NULL)
SCOTT@oracle10g>insert into tt1(object_id) select object_id from tt2;
469 rows created.
SCOTT@oracle10g>exec dbms_stats.gather_table_stats(user,'TT1');
PL/SQL procedure successfully completed.
SCOTT@oracle10g>set autot trace exp
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2);
Execution Plan
Plan hash value: 720405399
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |   489 |  7824 |   991   (1)| 00:00:12 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| TT1  |   490 |  7840 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |     1 |     5 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( NOT EXISTS (SELECT /*+ */ 0 FROM "TT2" "TT2" WHERE
              LNNVL("OBJECT_ID"<>:B1)))
   3 - filter(LNNVL("OBJECT_ID"<>:B1))
SCOTT@oracle10g>set autot off
SCOTT@oracle10g>select sql_id,child_number from v$sql where sql_text='select * from tt1 where object
_id not in (select object_id from tt2)';
SQL_ID        CHILD_NUMBER
dwag5726g0j91            1
SCOTT@oracle10g>select * from table(dbms_xplan.display_cursor('dwag5726g0j91',1));
PLAN_TABLE_OUTPUT
SQL_ID  dwag5726g0j91, child number 1
select * from tt1 where object_id not in (select object_id from tt2)
Plan hash value: 720405399
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |       |       |   991 (100)|          |
|*  1 |  FILTER            |      |       |       |            |          |
PLAN_TABLE_OUTPUT
|   2 |   TABLE ACCESS FULL| TT1  |   490 |  7840 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |     1 |     5 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( IS NULL)
   3 - filter(LNNVL("OBJECT_ID"<>:B1))
21 rows selected.
SCOTT@oracle10g>select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Prod
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for 32-bit Windows: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Productionwhen I modify tt1,query rewrite don't take effect ??

Answer 1

hi sir,
it take effects,but there are some problems.
SCOTT@oracle10g>insert into tt1(object_id) select object_id from tt2;
469 rows created.
Execution Plan
Plan hash value: 1248358058
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | INSERT STATEMENT  |      |   469 |  2345 |     4   (0)| 00:00:01 |
|   1 |  TABLE ACCESS FULL| TT2  |   469 |  2345 |     4   (0)| 00:00:01 |
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2); 
Execution Plan
Plan hash value: 720405399
| Id  | Operation          | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT   |      |   506 |  9614 |  1026   (1)| 00:00:13 |
|*  1 |  FILTER            |      |       |       |            |          |
|   2 |   TABLE ACCESS FULL| TT1  |   507 |  9633 |     3   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL| TT2  |     1 |     5 |     4   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - filter( NOT EXISTS (SELECT /*+ */ 0 FROM "TT2" "TT2" WHERE
              LNNVL("OBJECT_ID"<>:B1)))
   3 - filter(LNNVL("OBJECT_ID"<>:B1))
SCOTT@oracle10g>commit;
Commit complete.
SCOTT@oracle10g>select * from tt1 where object_id not in (select object_id from tt2);
Execution Plan
Plan hash value: 2314021845
| Id  | Operation            | Name | Rows  | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT     |      |    38 |   912 |     8  (13)| 00:00:01 |
|*  1 |  HASH JOIN RIGHT ANTI|      |    38 |   912 |     8  (13)| 00:00:01 |
|*  2 |   TABLE ACCESS FULL  | TT2  |   469 |  2345 |     4   (0)| 00:00:01 |
|*  3 |   TABLE ACCESS FULL  | TT1  |   507 |  9633 |     3   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   1 - access("OBJECT_ID"="OBJECT_ID")
   2 - filter("OBJECT_ID" IS NOT NULL)
   3 - filter("OBJECT_ID" IS NOT NULL)
   when I declare a new rewrite,enq: RW - MV metadata contention happens,and the blocking_session and blocked session are same session .
SYS@oracle10g>col event for a50
SYS@oracle10g>set linesize 300
SYS@oracle10g>select sid,serial#,event,blocking_session from v$session where username='SCOTT';
       SID    SERIAL# EVENT                                              BLOCKING_SESSION
       157          7 enq: RW - MV metadata contention                                157