Explain plan left the building

Question

Hello guys, i have interesting problem, at least it seemed to me like that.
I am on 10.2.0.4.0 and for every statement i do explain plan i get the same plan ???.
Propably very known issue to some, but i didn't exeperienced that till now, so if somene have some advice, please share.
E.g.
SQL> explain plan for select user from dual;
Explained.
SQL> select * from table(dbms_xplan.display);
Plan hash value: 3995103059
| Id  | Operation                    | Name           | Rows  | Bytes | Cost (%CPU)| Time     | Inst   |
|   0 | SELECT STATEMENT REMOTE      |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|   1 |  SORT ORDER BY               |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|*  2 |   TABLE ACCESS BY INDEX ROWID| CCONTACT_ALL   |     1 |    54 |     3   (0)| 00:00:01 | VIPBS~ |
|   3 |    NESTED LOOPS              |                |     1 |    96 | 97590   (5)| 00:05:07 |        |
|*  4 |     TABLE ACCESS FULL        | CUSTOMER_ALL   |     1 |    42 | 97587   (5)| 00:05:07 | VIPBS~ |
|*  5 |     INDEX RANGE SCAN         | PKCCONTACT_ALL |     1 |       |     2   (0)| 00:00:01 | VIPBS~ |
Predicate Information (identified by operation id):
   2 - filter("A1"."CCCONTRACT"='X')
   4 - filter((TO_NUMBER("A2"."CSCOMPTAXNO")=3007943362918 OR
              TO_NUMBER("A2"."PASSPORTNO")=0109965330447) AND (TO_NUMBER("A2"."CSLEVEL")=10 OR
              TO_NUMBER("A2"."CSLEVEL")=20 AND "A2"."TMCODE"<>59 AND "A2"."TMCODE"<>42 AND "A2"."TMCODE"<>61
              AND "A2"."TMCODE"<>11 AND "A2"."TMCODE"<>19) AND "A2"."CSTYPE"='a' AND "A2"."PAYMNTRESP"='X')
   5 - access("A1"."CUSTOMER_ID"="A2"."CUSTOMER_ID")
       filter("A1"."CUSTOMER_ID"<>0)
Note
   - 'PLAN_TABLE' is old version
   - fully remote statement
28 rows selected....so, it looks like i am doing all that just with select user from dual .... : ) ... ok
SQL> explain plan for
  2  SELECT param_value
  3  FROM ncis.cis_case_script_vars
  4  WHERE case_id = 296645706 AND seq = 1 AND param_name = 'OHOPNAMT';
Explained.
SQL> select * from table(dbms_xplan.display);
Plan hash value: 3995103059
| Id  | Operation                    | Name           | Rows  | Bytes | Cost (%CPU)| Time     | Inst   |
|   0 | SELECT STATEMENT REMOTE      |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|   1 |  SORT ORDER BY               |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|*  2 |   TABLE ACCESS BY INDEX ROWID| CCONTACT_ALL   |     1 |    54 |     3   (0)| 00:00:01 | VIPBS~ |
|   3 |    NESTED LOOPS              |                |     1 |    96 | 97590   (5)| 00:05:07 |        |
|*  4 |     TABLE ACCESS FULL        | CUSTOMER_ALL   |     1 |    42 | 97587   (5)| 00:05:07 | VIPBS~ |
|*  5 |     INDEX RANGE SCAN         | PKCCONTACT_ALL |     1 |       |     2   (0)| 00:00:01 | VIPBS~ |
Predicate Information (identified by operation id):
   2 - filter("A1"."CCCONTRACT"='X')
   4 - filter((TO_NUMBER("A2"."CSCOMPTAXNO")=3007943362918 OR
              TO_NUMBER("A2"."PASSPORTNO")=0109965330447) AND (TO_NUMBER("A2"."CSLEVEL")=10 OR
              TO_NUMBER("A2"."CSLEVEL")=20 AND "A2"."TMCODE"<>59 AND "A2"."TMCODE"<>42 AND "A2"."TMCODE"<>61
              AND "A2"."TMCODE"<>11 AND "A2"."TMCODE"<>19) AND "A2"."CSTYPE"='a' AND "A2"."PAYMNTRESP"='X')
   5 - access("A1"."CUSTOMER_ID"="A2"."CUSTOMER_ID")
       filter("A1"."CUSTOMER_ID"<>0)
Note
   - 'PLAN_TABLE' is old version
   - fully remote statement
28 rows selected.
SQL>..same plan for different sql...
..and now, i am trying to explain plan for several easy sqls but look...
SQL> explain plan for select * from all_objects where rownum < 2;
explain plan for select * from all_objects where rownum < 2
ERROR at line 1:
ORA-01039: insufficient privileges on underlying objects of the view
SQL> explain plan for select * from user_tables ;
explain plan for select * from user_tables
ERROR at line 1:
ORA-01039: insufficient privileges on underlying objects of the view
SQL> desc all_objects
Name                                                                    Null?    Type
OWNER                                                                   NOT NULL VARCHAR2(30)
OBJECT_NAME                                                             NOT NULL VARCHAR2(30)
SUBOBJECT_NAME                                                                   VARCHAR2(30)
OBJECT_ID                                                               NOT NULL NUMBER
DATA_OBJECT_ID                                                                   NUMBER
OBJECT_TYPE                                                                      VARCHAR2(19)
CREATED                                                                 NOT NULL DATE
LAST_DDL_TIME                                                           NOT NULL DATE
TIMESTAMP                                                                        VARCHAR2(19)
STATUS                                                                           VARCHAR2(7)
TEMPORARY                                                                        VARCHAR2(1)
GENERATED                                                                        VARCHAR2(1)
SECONDARY                                                                        VARCHAR2(1)...i can't figure this out... maybe i have to flush 'explain plan' ? it's ok if it sounds funny,im off with ideas..
then i tried to explain this sql:
SQL> explain plan for
  2  SELECT param_value
  3  FROM ncis.cis_case_script_vars
  4  WHERE case_id = 296645706 AND seq = 1 AND param_name = 'OHOPNAMT';
Explained.
SQL> select * from table(dbms_xplan.display);
Plan hash value: 3995103059
| Id  | Operation                    | Name           | Rows  | Bytes | Cost (%CPU)| Time     | Inst   |
|   0 | SELECT STATEMENT REMOTE      |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|   1 |  SORT ORDER BY               |                |     1 |    96 | 97591   (5)| 00:05:07 |        |
|*  2 |   TABLE ACCESS BY INDEX ROWID| CCONTACT_ALL   |     1 |    54 |     3   (0)| 00:00:01 | VIPBS~ |
|   3 |    NESTED LOOPS              |                |     1 |    96 | 97590   (5)| 00:05:07 |        |
|*  4 |     TABLE ACCESS FULL        | CUSTOMER_ALL   |     1 |    42 | 97587   (5)| 00:05:07 | VIPBS~ |
|*  5 |     INDEX RANGE SCAN         | PKCCONTACT_ALL |     1 |       |     2   (0)| 00:00:01 | VIPBS~ |
Predicate Information (identified by operation id):
   2 - filter("A1"."CCCONTRACT"='X')
   4 - filter((TO_NUMBER("A2"."CSCOMPTAXNO")=3007943362918 OR
              TO_NUMBER("A2"."PASSPORTNO")=0109965330447) AND (TO_NUMBER("A2"."CSLEVEL")=10 OR
              TO_NUMBER("A2"."CSLEVEL")=20 AND "A2"."TMCODE"<>59 AND "A2"."TMCODE"<>42 AND "A2"."TMCODE"<>61
              AND "A2"."TMCODE"<>11 AND "A2"."TMCODE"<>19) AND "A2"."CSTYPE"='a' AND "A2"."PAYMNTRESP"='X')
   5 - access("A1"."CUSTOMER_ID"="A2"."CUSTOMER_ID")
       filter("A1"."CUSTOMER_ID"<>0)
Note
   - 'PLAN_TABLE' is old version
   - fully remote statement
28 rows selected.
SQL>..and got the same plan again....
anyone with suggestons, anyone encountered this behaviour ?

Answer 1

Vili Dialis wrote:
Is there some way to force usage of one of them explicitly, how can i know which one is currently used ?
So what happend here ?
I am using what plan table of the above, and why that table generates always the same plan ?
*/To bypass the problem (probably), and to see how it happened (possibly) see http://jonathanlewis.wordpress.com/2010/01/25/old-plan_table/
Not sure why you keep getting the same plan, but dbms_xplan does a 'select where plan_id = (select max(plan_id) ..) so perhaps the plan_table(s) you keep using have an artificially high plan_id which is always getting selected. (You could try doing: delete from plan_table ; commit; )
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
A general reminder about "Forum Etiquette / Reward Points": http://forums.oracle.com/forums/ann.jspa?annID=718
If you never mark your questions as answered people will eventually decide that it's not worth trying to answer you because they will never know whether or not their answer has been of any use, or whether you even bothered to read it.
It is also important to mark answers that you thought helpful - again it lets other people know that you appreciate their help, but it also acts as a pointer for other people when they are researching the same question, moreover it means that when you mark a bad or wrong answer as helpful someone may be prompted to tell you (and the rest of the forum) what's so bad or wrong about the answer you found helpful.