分页SQL取下一页

20条记录一页,扫描第2页就需要访问40条记录。



SQL> select * from ( select * from ( select /*+ index_desc(a idx_page_3) */ a.*,rownum rn   from page

a  where object_id >1000 and owner='SYS'  order by object_id desc ) where rownum<=40 ) where

rn>=21  2    3  

  4  ;





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



PLAN_TABLE_OUTPUT

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



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

SQL_ID	bwcbf54a6h4th, child number 1

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

select * from ( select * from ( select /*+ index_desc(a idx_page_3) */

a.*,rownum rn	from page a  where object_id >1000 and owner='SYS'

order by object_id desc ) where rownum<=40 ) where rn>=21



Plan hash value: 3526010999



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

| Id  | Operation			 | Name       | Starts | E-Rows | A-Rows |   A-Time   | Buffers |

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

|   0 | SELECT STATEMENT		 |	      |      1 |	|     20 |00:00:00.01 |      10 |

|*  1 |  VIEW				 |	      |      1 |     40 |     20 |00:00:00.01 |      10 |

|*  2 |   COUNT STOPKEY 		 |	      |      1 |	|     40 |00:00:00.01 |      10 |

|   3 |    VIEW 			 |	      |      1 |  30556 |     40 |00:00:00.01 |      10 |

|   4 |     COUNT			 |	      |      1 |	|     40 |00:00:00.01 |      10 |

|   5 |      TABLE ACCESS BY INDEX ROWID | PAGE       |      1 |  30556 |     40 |00:00:00.01 |      10 |

|*  6 |       INDEX RANGE SCAN DESCENDING| IDX_PAGE_3 |      1 |  30556 |     40 |00:00:00.01 |       4 |

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



Predicate Information (identified by operation id):

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



   1 - filter("RN">=21)

   2 - filter(ROWNUM<=40)

   6 - access("OBJECT_ID" IS NOT NULL AND "OBJECT_ID">1000 AND "OWNER"='SYS')

       filter("OWNER"='SYS')





28 rows selected.





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



PLAN_TABLE_OUTPUT

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



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

SQL_ID	6gay6kkxxsqgw, child number 0

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

select * from ( select * from ( select /*+ index_desc(a idx_page_3) */

a.*,rownum rn	from page a  where object_id >1000 and owner='SYS'

order by object_id desc ) where rownum<=60 ) where rn>=41



Plan hash value: 3526010999



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

| Id  | Operation			 | Name       | Starts | E-Rows | A-Rows |   A-Time   | Buffers |

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

|   0 | SELECT STATEMENT		 |	      |      1 |	|     20 |00:00:00.01 |      11 |

|*  1 |  VIEW				 |	      |      1 |     60 |     20 |00:00:00.01 |      11 |

|*  2 |   COUNT STOPKEY 		 |	      |      1 |	|     60 |00:00:00.01 |      11 |

|   3 |    VIEW 			 |	      |      1 |  30556 |     60 |00:00:00.01 |      11 |

|   4 |     COUNT			 |	      |      1 |	|     60 |00:00:00.01 |      11 |

|   5 |      TABLE ACCESS BY INDEX ROWID | PAGE       |      1 |  30556 |     60 |00:00:00.01 |      11 |

|*  6 |       INDEX RANGE SCAN DESCENDING| IDX_PAGE_3 |      1 |  30556 |     60 |00:00:00.01 |       4 |

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



Predicate Information (identified by operation id):

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



   1 - filter("RN">=41)

   2 - filter(ROWNUM<=60)

   6 - access("OBJECT_ID" IS NOT NULL AND "OBJECT_ID">1000 AND "OWNER"='SYS')

       filter("OWNER"='SYS')





28 rows selected.