-- dba.v_data_hit_ratio - data hit ratio (DHR)

-- Downloaded from http://www.ebenner.com/db2luwdba-howto
-- For use only with other components from article series:
-- "Effective DB2 Monitoring with Snapshot Administrative Views"
-- by Jeffrey Benner, in _DB2 LUW DBA HowTo_
-- Please direct any questions to consulting@ebenner.com

-- This work is licensed under the Creative Commons Attribution 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.

create view dba.v_data_hit_ratio as
with POOL_DATA_L_READS_DELTA_TB as
(select snap0.SNAPSHOT_TIMESTAMP,
( POOL_DATA_L_READS  -
         ( select POOL_DATA_L_READS
          from dba.snapdb as SNAP1
          where snap1.SNAPSHOT_TIMESTAMP = ( select max(snap2.SNAPSHOT_TIMESTAMP)
                                             from dba.snapdb as SNAP2
                                             where snap2.SNAPSHOT_TIMESTAMP < snap0.SNAPSHOT_TIMESTAMP
                                           )

         )
) as POOL_DATA_L_READS_DELTA
from dba.snapdb as SNAP0 ),

POOL_DATA_P_READS_DELTA_TB as
(select snap0.SNAPSHOT_TIMESTAMP,
( POOL_DATA_P_READS  -
         ( select POOL_DATA_P_READS
          from dba.snapdb as SNAP1
          where snap1.SNAPSHOT_TIMESTAMP = ( select max(snap2.SNAPSHOT_TIMESTAMP)
                                             from dba.snapdb as SNAP2
                                             where snap2.SNAPSHOT_TIMESTAMP < snap0.SNAPSHOT_TIMESTAMP
                                           )

         )
) as POOL_DATA_P_READS_DELTA
from dba.snapdb as SNAP0 )

select A.SNAPSHOT_TIMESTAMP,
CASE
WHEN POOL_DATA_L_READS_DELTA = 0 then 0
ELSE 100 - (DECIMAL((DECIMAL(POOL_DATA_P_READS_DELTA, 23, 4)
/ DECIMAL( POOL_DATA_L_READS_DELTA, 23, 4)) * 100, 8, 1))
END as dhr_pct
from POOL_DATA_L_READS_DELTA_TB A, POOL_DATA_P_READS_DELTA_TB C
where A.SNAPSHOT_TIMESTAMP = C.SNAPSHOT_TIMESTAMP ;