query

I was looking online for this issue: are you able to know when a parameter was changed in your database or also track all parameters changes in your database? Kerry Osborne has the solution. Even if you’re able to check in your alert log file for changes (Oracle logs every changes to parameters) you can also use AWR! Table WRH$_PARAMETER holds the answer.

select instance_number instance, snap_id, time, parameter_name, old_value, new_value from (
select a.snap_id,to_char(end_interval_time,'DD-MON-YY HH24:MI') TIME,  a.instance_number, parameter_name, value new_value,
lag(parameter_name,1) over (partition by parameter_name, a.instance_number order by a.snap_id) old_pname,
lag(value,1) over (partition by parameter_name, a.instance_number  order by a.snap_id) old_value ,
decode(substr(parameter_name,1,2),'__',2,1) calc_flag
from dba_hist_parameter a, dba_Hist_snapshot b , v$instance v
where a.snap_id=b.snap_id
and a.instance_number=b.instance_number
and parameter_name like nvl('&parameter_name',parameter_name)
and a.instance_number like nvl('&instance_number',v.instance_number)
)
where
new_value != old_value
and calc_flag not in (decode('&show_calculated','Y',3,2))
order by 1,2
/

Original query (by Kerry Osborne) is available here. For the whole explaination check the trackback.