按照如下方法进行海量数据的查询,不加WHERE条件的话,速度很快,但加了WHERE条年,速度还是很慢呀,请问WHER条件应加在哪里比较适合?
表TABLENAME按ORDERBYFIELD建立索引,
select /*+ first_row */ fields
from TABLENAME
where rowid in (select rid from (select rownum rno, rid
from (select rowid rid from TABLENAME
order by ORDERBYFIELD desc)
where rownum <= 800000 )
where rno >= 799981);
表TABLENAME按ORDERBYFIELD建立索引,
select /*+ first_row */ fields
from TABLENAME
where rowid in (select rid from (select rownum rno, rid
from (select rowid rid from TABLENAME
order by ORDERBYFIELD desc)
where rownum <= 800000 )
where rno >= 799981);
select * from TABLENAME where rownum<800000