Database is transfered between storage server and database server . Exadata is meant to deliver performance. Therefore the amount of data that should be reduced by oracle. So oracle implemented new feature called Storage index
When ever a table is queried by different range of values, storage index is created on the storage server automatically no additional set up is required. It will keep minimum and maximum range of values with in the cells by storing in a block . The amount of I/O saved by storage index can be known by this following query
Query to check I/O bytes saved by storage Index
col stat_value format 9,999.9999
select
name,value/1024/1024 as stat_value from v$mystat s, v$statname n
where
s.statistic# = n.statistic#
and
n.name in (
' cell physical IO bytes saved by storage index’,
‘cell physical IO interconnect bytes returned by smart scan’
)
/
_kcfis_storageidx_disabled is parameter that controls on database to enable or disable storage index on exadata storage server. By default it is false. If you set it to True, i.e storage index will be disabled
--Nikhil Tatineni--
--Exadata--
