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    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.

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  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13352402.html
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