oracle 10g下范围分区扫描的几种方式

oracle 10g下有几种扫描方式，注意最后一种扫描方式，当对分区的列进行计算时，会不走分区。这跟对索引列进行计算会导致无法用索引一样。

--扫描单个分区  PARTITION RANGE SINGLE

   --连续扫描多个分区 PARTITION RANGE ITERATOR

   --不连续扫描多个分区  PARTITION RANGE INLIST

   --扫描全分区 PARTITION RANGE ALL

SQL> drop table t_range purge;

SQL> create table t_range (id number not null PRIMARY KEY, test_date date) partition by range (test_date)

    (

    partition p_1 values less than (to_date('2013-12-01', 'yyyy-mm-dd')),

    partition p_2 values less than (to_date('2014-02-01', 'yyyy-mm-dd')),

    partition p_3 values less than (to_date('2014-03-01', 'yyyy-mm-dd')),

    partition p_4 values less than (to_date('2014-04-01', 'yyyy-mm-dd')),

    partition p_5 values less than (to_date('2014-05-01', 'yyyy-mm-dd')),

    partition p_6 values less than (to_date('2014-06-01', 'yyyy-mm-dd')),

    partition p_max values less than (MAXVALUE)

   ) nologging;

SQL> insert /*+append */ into t_range  select rownum,

           to_date(to_char(sysdate - 140, 'J') +

                   trunc(dbms_random.value(0, 80)),

                   'J')

      from dual

    connect by rownum <= 100000;

SQL> commit;

SQL> exec dbms_stats.gather_table_stats(user,'T_RANGE');

SQL> select to_char(t.test_date,'yyyy-MM'),count(1) from t_range t

     group by to_char(t.test_date,'yyyy-MM');

TO_CHAR   COUNT(1)

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

2014-01      38803

2014-03      11242

2013-12      15107

2014-02      34848



SQL> set autotrace traceonly

--扫描单个分区

SQL> select * from t_range  where test_date = to_date('2014-04-28', 'yyyy-mm-dd');

运行计划

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

Plan hash value: 3010141842

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

| Id  | Operation              | Name    | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |

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

|   0 | SELECT STATEMENT       |         |     1 |    22 |     2   (0)| 00:00:01 |       |       |

|   1 |  PARTITION RANGE SINGLE|         |     1 |    22 |     2   (0)| 00:00:01 |     5 |     5 |

|*  2 |   TABLE ACCESS FULL    | T_RANGE |     1 |    22 |     2   (0)| 00:00:01 |     5 |     5 |

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

Predicate Information (identified by operation id):

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

   2 - filter("TEST_DATE"=TO_DATE('2014-04-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss'))

统计信息

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

          1  recursive calls

          0  db block gets

          3  consistent gets

          0  physical reads

          0  redo size

        327  bytes sent via SQL*Net to client

        374  bytes received via SQL*Net from client

          1  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

          0  rows processed



--连续扫描多个分区

SQL> select *  from t_range

     where test_date <= to_date('2014-04-28', 'yyyy-mm-dd')

       and test_date >= to_date('2014-02-28', 'yyyy-mm-dd');

运行计划

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

Plan hash value: 1921532398

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

| Id  | Operation                | Name    | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |

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

|   0 | SELECT STATEMENT         |         | 12556 |   147K|    28   (0)| 00:00:01 |       |       |

|   1 |  PARTITION RANGE ITERATOR|         | 12556 |   147K|    28   (0)| 00:00:01 |     3 |     5 |

|*  2 |   TABLE ACCESS FULL      | T_RANGE | 12556 |   147K|    28   (0)| 00:00:01 |     3 |     5 |

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

Predicate Information (identified by operation id):

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

   2 - filter("TEST_DATE">=TO_DATE('2014-02-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss') AND

              "TEST_DATE"<=TO_DATE('2014-04-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss'))

统计信息

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

          1  recursive calls

          0  db block gets

        956  consistent gets

          0  physical reads

          0  redo size

     309138  bytes sent via SQL*Net to client

       9515  bytes received via SQL*Net from client

        832  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

      12453  rows processed



--不连续扫描多个分区

SQL> select *  from t_range

     where test_date = to_date('2014-04-28', 'yyyy-mm-dd')

       or test_date = to_date('2014-02-28', 'yyyy-mm-dd');

运行计划

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

Plan hash value: 2021067984

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

| Id  | Operation              | Name    | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |

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

|   0 | SELECT STATEMENT       |         |  1678 | 20136 |    21   (0)| 00:00:01 |       |       |

|   1 |  PARTITION RANGE INLIST|         |  1678 | 20136 |    21   (0)| 00:00:01 |KEY(I) |KEY(I) |

|*  2 |   TABLE ACCESS FULL    | T_RANGE |  1678 | 20136 |    21   (0)| 00:00:01 |KEY(I) |KEY(I) |

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

Predicate Information (identified by operation id):

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

   2 - filter("TEST_DATE"=TO_DATE('2014-02-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss') OR

              "TEST_DATE"=TO_DATE('2014-04-28 00:00:00', 'yyyy-mm-dd hh24:mi:ss'))

统计信息

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

          1  recursive calls

          0  db block gets

        175  consistent gets

          0  physical reads

          0  redo size

      22646  bytes sent via SQL*Net to client

       1265  bytes received via SQL*Net from client

         82  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

       1211  rows processed





--扫描全分区

SQL> select * from t_range where to_char(test_date,'yyyy-MM-dd')='2014-04-01';

运行计划

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

Plan hash value: 2128486036

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

| Id  | Operation           | Name    | Rows  | Bytes | Cost (%CPU)| Time     | Pstart| Pstop |

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

|   0 | SELECT STATEMENT    |         |   994 | 11928 |    59   (4)| 00:00:01 |       |       |

|   1 |  PARTITION RANGE ALL|         |   994 | 11928 |    59   (4)| 00:00:01 |     1 |     7 |

|*  2 |   TABLE ACCESS FULL | T_RANGE |   994 | 11928 |    59   (4)| 00:00:01 |     1 |     7 |

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

Predicate Information (identified by operation id):

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

   2 - filter(TO_CHAR(INTERNAL_FUNCTION("TEST_DATE"),'yyyy-MM-dd')='2014-04-01')

统计信息

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

          1  recursive calls

          0  db block gets

        272  consistent gets

          0  physical reads

          0  redo size

        327  bytes sent via SQL*Net to client

        374  bytes received via SQL*Net from client

          1  SQL*Net roundtrips to/from client

          0  sorts (memory)

          0  sorts (disk)

          0  rows processed