如何优化oracle分页语句

Question

如何以下优化oracle分页语句？
select * from (select 
                           substr(km.sm_content, 0, 24) || '....' ct, 
                            km.sm_content,
                           case when km.total_count>10000 then round(40+(km.total_count-10000)*1.6/1000,0) else 0 end money,
                           substr(zu.usernickname, 0,6) shortname,
                           km.total_count, 
                           to_char(km.pass_time, 'YY-MM-DD') pt,
                           zu.usernickname,zu.username,
                           km.key_message_id, 
                           row_number() over(order by km.Total_Count desc) rn
                           from zk_product z
                           left join key_message_new km on z.prosourceid = km.key_message_id 
                           left join zk_users zu on zu.userid = z.userid 
                           where km.audit_tag >= 2 and km.user_visible = 1 and km.key_status = 1) where rn between 1 and 10

Answer 1

select * from (select 
                          substr(km.sm_content, 0, 24) || '....' ct, 
                            km.sm_content, 
                          case when km.total_count>10000 then round(40+(km.total_count-10000)*1.6/1000,0) else 0 end money, 
                          substr(zu.usernickname, 0,6) shortname, 
                          km.total_count, 
                          to_char(km.pass_time, 'YY-MM-DD') pt, 
                          zu.usernickname,zu.username, 
                          km.key_message_id, 
                          row_number() over(order by km.Total_Count desc) rn 
                          from zk_product z 
                          left join key_message_new km on z.prosourceid = km.key_message_id 
                          left join zk_users zu on zu.userid = z.userid 
                          where km.audit_tag >= 2 and km.user_visible = 1 and km.key_status = 1 and rn<=10) where rn >=1

Answer 2

rown_number()没有意义
直接order by配合rownum就可以了
... rownum as _row order by km.Total_Count desc) where _row between 1 and 10