Oracle 11g Release 2

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create table docs(how_to_use_dbfiddle) as
select 'Enter one statement per field' from dual union all
select 'Fields grow as you type' from dual union all
select 'Use the [+] buttons to add more' from dual union all
select 'See examples below for advanced usage' from dual;
4 rows affected

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-- ② Execution Plans 
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-- see https://jonathanlewis.wordpress.com/2006/11/09/dbms_xplan-in-10g;
--------------------------------------------------------------------------------
select /*+ gather_plan_statistics */
       'Do this to get execution plans and actual execution stats' "Execution Plans"
from docs cross join docs
group by 'A';

Execution Plans

Do this to get execution plans and actual execution stats

select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST'));

PLAN_TABLE_OUTPUT

SQL_ID  6qjky6tsw3chb, child number 0

-------------------------------------

------------------------------------------------------------------------

-------- -- ??? Execution Plans  ---------------------------------------

----------------------------------------- -- see

https://jonathanlewis.wordpress.com/2006/11/09/dbms_xplan-in-10g;

------------------------------------------------------------------------

-------- select /*+ gather_plan_statistics */        'Do this to get

execution plans and actual execution stats' "Execution Plans" from docs

cross join docs group by 'A'

Plan hash value: 3410957799

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| Id  | Operation             | Name | Starts | E-Rows | A-Rows |   A-Time   | Buffers |  OMem |  1Mem | Used-Mem |

-------------------------------------------------------------------------------------------------------------------

|   0 | SELECT STATEMENT      |      |      1 |        |      1 |00:00:00.01 |       6 |       |       |          |

|   1 |  SORT GROUP BY NOSORT |      |      1 |     16 |      1 |00:00:00.01 |       6 |       |       |          |

|   2 |   MERGE JOIN CARTESIAN|      |      1 |     16 |     16 |00:00:00.01 |       6 |       |       |          |

|   3 |    TABLE ACCESS FULL  | DOCS |      1 |      4 |      4 |00:00:00.01 |       3 |       |       |          |

|   4 |    BUFFER SORT        |      |      4 |      4 |     16 |00:00:00.01 |       3 |  2048 |  2048 | 2048  (0)|

|   5 |     TABLE ACCESS FULL | DOCS |      1 |      4 |      4 |00:00:00.01 |       3 |       |       |          |

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Note

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   - dynamic sampling used for this statement (level=2)