目前sql 如下，执行速度较慢
T1,T2 约200万记录
T3 约500万

select * from( select rownum rn ,c.* from (select
T3.rowid T3_id,
T3.recno, T3.pdate

from T3
JOIN T2 on T2.idnum=T3.idnum and T2.recno=T3.recno
JOIN T1 on T3.idnum=T1.idnum

where T3.dumpstatus<>'-'
and (T1.OSTATUS not in ('C','P'))
and T2.PCODE = 'IC'
and T1.confirm = 'Y'
and (T3.pdate>=to_date('20100401','yyyymmdd'))
and (T3.pdate<=to_date('20100531','yyyymmdd'))
and (T3.dumpstatus <> 'C')

Order By T3.idnum desc,T3.recno asc, T3.pdate asc

)c where rownum<=3000
) where rn >1500