全表扫描分页

SQL> set linesize 200

SQL> set pagesize 200

SQL> alter session set statistics_level=all; 



Session altered.



SQL> select  *  from ( select rownum as rn ,a.* from ( select

*	from page a   )a where rownum<=20 ) a  where rn>=0  2  ;



20 rows selected.



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



PLAN_TABLE_OUTPUT

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



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

SQL_ID	axby03b75am6v, child number 0

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

select	*  from ( select rownum as rn ,a.* from ( select * from page a

 )a where rownum<=20 ) a  where rn>=0



Plan hash value: 2590430161



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

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

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

|   0 | SELECT STATEMENT    |	   |	  1 |	     |	   20 |00:00:00.01 |	   6 |

|*  1 |  VIEW		    |	   |	  1 |	  20 |	   20 |00:00:00.01 |	   6 |

|*  2 |   COUNT STOPKEY     |	   |	  1 |	     |	   20 |00:00:00.01 |	   6 |

|   3 |    TABLE ACCESS FULL| PAGE |	  1 |	  20 |	   20 |00:00:00.01 |	   6 |

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



Predicate Information (identified by operation id):

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



   1 - filter("RN">=0)

   2 - filter(ROWNUM<=20)





22 rows selected.





取第2页:



SQL> select  *  from ( select rownum as rn ,a.* from ( select

*	from page a   )a where rownum<=40 ) a  where rn>=21  2  ;





20 rows selected.



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



PLAN_TABLE_OUTPUT

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



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

SQL_ID	crwugd6xrr3nb, child number 0

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

select	*  from ( select rownum as rn ,a.* from ( select * from page a

 )a where rownum<=40 ) a  where rn>=21



Plan hash value: 2590430161



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

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

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

|   0 | SELECT STATEMENT    |	   |	  1 |	     |	   20 |00:00:00.01 |	   6 |

|*  1 |  VIEW		    |	   |	  1 |	  40 |	   20 |00:00:00.01 |	   6 |

|*  2 |   COUNT STOPKEY     |	   |	  1 |	     |	   40 |00:00:00.01 |	   6 |

|   3 |    TABLE ACCESS FULL| PAGE |	  1 |	  40 |	   40 |00:00:00.01 |	   6 |

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



Predicate Information (identified by operation id):

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



   1 - filter("RN">=21)

   2 - filter(ROWNUM<=40)





22 rows selected.