Comments on: Which segments have top LIO (Logical IO)/PIO (Physical I/O)

By: OrcaXXX

OrcaXXX — Tue, 07 Feb 2006 09:18:54 +0000

Hi, best results i got with this SQL; Value must be greater zero - otherwise dense_rank() puts always the same rank again on the retrieved rowset (had a lot of entries with same value 0)

SELECT *
  FROM (SELECT Statistic_Name,
               St.Owner,
               St.Obj#,
               St.Object_Type,
               St.Object_Name,
               St.VALUE,
               Dense_Rank() 
                 Over(PARTITION BY Statistic_Name ORDER BY St.VALUE DESC) Rnk
          FROM V$segment_Statistics St
         WHERE St.VALUE > 0
           AND St.Statistic_Name IN
               ('physical reads', 'physical writes', 'logical reads',
                'physical reads direct', 'physical writes direct'))
 WHERE Rnk <= 10

By: OrcaXXX

OrcaXXX — Thu, 02 Feb 2006 20:26:49 +0000

Thanks to Eddie and Ray;
So that’s a good example too showing/comparing the power of analytic functions and the ‘old’ way :-)))
Karl

By: rjamya

rjamya — Wed, 01 Feb 2006 21:04:54 +0000

Thanks Eddie,

I don’t seem to be able to format very well. and I didn’t filter the statistic name. If you wish to filter, put it inside the inline view.

Raj

By: Eddie Awad

Eddie Awad — Wed, 01 Feb 2006 20:36:56 +0000

I believe this is what rjamya had in mind:

select *
from
  (select statistic_name,
     st.owner,
     st.obj#,
     st.object_type,
     st.object_name,
     st.value,
     dense_rank() over(partition by statistic_name
   order by st.value desc) rnk
   from v$segment_statistics st)
where rnk <= 10
 and statistic_name in ('logical reads', 'physical reads')

Analytic functions are very powerful.

By: OrcaXXX

OrcaXXX — Wed, 01 Feb 2006 20:18:13 +0000

OH!
You find a shortcut for this; will try your version soon. I must admit that i am not used to all kind of analytic functions. :-)
Karl

By: rjamya

rjamya — Wed, 01 Feb 2006 18:45:11 +0000

What is wrong with

SELECT *
FROM
(SELECT STATISTIC_NAME, ST.OWNER,ST.OBJ#,
  ST.OBJECT_TYPE,
  ST.OBJECT_NAME,ST.VALUE,
  DENSE_RANK() OVER(PARTITION BY STATISTIC_NAME ORDER BY ST.VALUE DESC) RNK
FROM   V$SEGMENT_STATISTICS ST)
WHERE  RNK

rjamya