DBA AWR Settings

➜ Back to Library
Description
Categories: Diagnostic Pack, Enginatics, Toolkit - DBA
Repository: Github
Automatic workload repository settings such as retention period, snapshot interval and number of top SQLs to capture (from table underlying the view dba_hist_wr_control).
Note that for executing Blitz Report queries on AWR data, you require a Diagnostic pack license as explained in Oracle's note 1490798.1:
https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=1490798.1 ...  Automatic workload repository settings such as retention period, snapshot interval and number of top SQLs to capture (from table underlying the view dba_hist_wr_control).
Note that for executing Blitz Report queries on AWR data, you require a Diagnostic pack license as explained in Oracle's note 1490798.1:
https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=1490798.1

topnsql=DEFAULT means the database captures the top 30 SQLs from 5 different categories (Elapsed Time, CPU Time, Parse Calls, Shareable Memory, Version Count) for each snapshot interval.
So the default setting would capture a maximum of 150 different SQLs per snapshot, depending on system load.

Settings are modified by package dbms_workload_repository where interval parameters passed are specified in minutes.
Example: A 35 days retention with snapshot intervals of 30 minutes and 50 top SQLs captured is set as follows:

exec dbms_workload_repository.modify_snapshot_settings (retention=>35*1440, interval=>30, topnsql=>50);

A common problem is that AWR records are not getting purged, see Oracle note 1292724.1.
If column 'Orphan Sess History Count' is bigger than zero, then orphan records not belonging to the current DB's snapshots should get purged either 'manually' table by table:

delete /*+ parallel(x 4) */ from wrh$_active_session_history wash where (wash.dbid, wash.instance_number, wash.snap_id) not in (select ws.dbid, ws.instance_number, ws.snap_id from wrm$_snapshot ws)
alter table wrh$_active_session_history shrink space cascade;

or by a generic script:

begin
for c in (
select x.* from (
select distinct
dt.num_rows,
dt.row_movement,
dtc.table_name,
listagg(dtc.column_name,', ') within group (order by dtc.column_name) over (partition by dtc.table_name) table_columns,
count(*) over (partition by dtc.table_name) column_count
from
dba_tables dt,
dba_tab_columns dtc
where
dt.owner=dtc.owner and
dt.table_name=dtc.table_name and
dtc.owner='SYS' and
dtc.table_name like 'WRH$\_%' escape '\' and
dtc.column_name in ('DBID','INSTANCE_NUMBER','SNAP_ID')
) x
where
x.table_columns in ('DBID, INSTANCE_NUMBER, SNAP_ID','DBID, SNAP_ID')
order by
x.num_rows desc
) loop
if c.table_columns='DBID, INSTANCE_NUMBER, SNAP_ID' then
execute immediate '
delete /*+ parallel(x 4) */
'||c.table_name||' x
where
x.dbid is not null and
x.instance_number is not null and
x.snap_id is not null and
(x.dbid, x.instance_number, x.snap_id) not in (select ws.dbid, ws.instance_number, ws.snap_id from wrm$_snapshot ws)';
dbms_output.put_line(sql%rowcount||' records deleted from '||c.table_name);
elsif c.table_columns='DBID, SNAP_ID' then
execute immediate '
delete /*+ parallel(x 4) */
'||c.table_name||' x
where
x.dbid is not null and
x.snap_id is not null and
(x.dbid, x.snap_id) not in (select ws.dbid, ws.snap_id from wrm$_snapshot ws)';
dbms_output.put_line(sql%rowcount||' records deleted from '||c.table_name);
end if;
if c.row_movement='ENABLED' then
execute immediate 'alter table '||c.table_name||' shrink space cascade';
dbms_output.put_line(c.table_name||' shrinked');
end if;
commit;
end loop;
end;

To purge obsolete data from old DBIDs:
http://www.strategicdbs.com/p/removing-old-dbid-data.html

begin
for c in (select distinct dfus.dbid from dba_feature_usage_statistics dfus where dfus.dbid not in (select vd.dbid from v$database vd)) loop
dbms_swrf_internal.unregister_database(c.dbid);
end loop;
delete wri$_dbu_usage_sample wdus where wdus.dbid not in (select vd.dbid from v$database vd);
delete wri$_dbu_feature_usage wdfu where wdfu.dbid not in (select vd.dbid from v$database vd);
delete wri$_dbu_high_water_mark wdhwm where wdhwm.dbid not in (select vd.dbid from v$database vd);
delete wri$_dbu_cpu_usage wdcu where wdcu.dbid not in (select vd.dbid from v$database vd);
delete wri$_dbu_cpu_usage_sample wdcus where wdcus.dbid not in (select vd.dbid from v$database vd);
commit;
end;   more
Run DBA AWR Settings and other Oracle EBS reports with Blitz Report™ on our demo environment
select
vd.name database,
dhdi.host_name,
dhdi.instance_name,
case when extract(day from dhwc.retention)>0 then extract(day from dhwc.retention)||'d ' end||
case when extract(hour from dhwc.retention)>0 then extract(hour from dhwc.retention)||'h ' end||
case when extract(minute from dhwc.retention)>0 then extract(minute from dhwc.retention)||'m ' end||
case when extract(second from dhwc.retention)>0 then extract(second from dhwc.retention)||'s' end retention,
case when extract(day from dhwc.snap_interval)>0 then extract(day from dhwc.snap_interval)||'d ' end||
case when extract(hour from dhwc.snap_interval)>0 then extract(hour from dhwc.snap_interval)||'h ' end||
case when extract(minute from dhwc.snap_interval)>0 then extract(minute from dhwc.snap_interval)||'m ' end||
case when extract(second from dhwc.snap_interval)>0 then extract(second from dhwc.snap_interval)||'s' end snap_interval,
dhwc.topnsql,
dhs.count snapshot_count,
(select count(*) from dba_hist_sqlstat dhss where dhdi.dbid=dhss.dbid and dhdi.instance_number=dhss.instance_number) sqlstat_count,
(select count(*) from dba_hist_active_sess_history dhash where (dhash.dbid, dhash.instance_number, dhash.snap_id) in (select dhs.dbid, dhs.instance_number, dhs.snap_id from dba_hist_snapshot dhs where dhdi.dbid=dhs.dbid and dhdi.instance_number=dhs.instance_number)) active_sess_history_count,
(select count(*) from sys.wrh$_active_session_history wash where (wash.dbid, wash.instance_number, wash.snap_id) not in (select ws.dbid, ws.instance_number, ws.snap_id from sys.wrm$_snapshot ws where dhdi.dbid=ws.dbid)) orphan_sess_history_count,
(select count(*) from sys.wrh$_sysmetric_history wsh where (wsh.dbid, wsh.instance_number, wsh.snap_id) not in (select ws.dbid, ws.instance_number, ws.snap_id from sys.wrm$_snapshot ws where dhdi.dbid=ws.dbid)) orphan_sysmetric_history_count,
xxen_util.client_time(dhs.startup_time) startup_time,
xxen_util.client_time(dhs.most_recent_snap_time) most_recent_snap_time,
dhdi.dbid
from
dba_hist_wr_control dhwc,
v$database vd,
(select x.* from (select max(dhdi.startup_time) over (partition by dhdi.dbid, dhdi.instance_number) max_startup_time, dhdi.* from dba_hist_database_instance dhdi) x where x.startup_time=x.max_startup_time) dhdi,
(
select distinct
dhs.dbid,
dhs.instance_number,
count(*) over (partition by dhs.dbid, dhs.instance_number) count,
max(dhs.startup_time) over (partition by dhs.dbid, dhs.instance_number) startup_time,
max(dhs.end_interval_time) over (partition by dhs.dbid, dhs.instance_number) most_recent_snap_time
from
dba_hist_snapshot dhs
) dhs
where
1=1 and
dhwc.dbid=vd.dbid and
dhwc.dbid=dhdi.dbid(+) and
dhdi.dbid=dhs.dbid(+) and
dhdi.instance_number=dhs.instance_number(+)
order by
dhdi.startup_time desc
Parameter Name SQL text Validation
Diagnostic Pack enabled 
1=1
 LOV
Download
 
Related Blitz Reports
DBA SGA+PGA Memory Configuration DBA AWR System Wait Time Summary DBA AWR Blocking Session Summary DBA AWR Active Session History DBA AWR Latch Summary DBA AWR System Wait Class by Time DBA AWR SQL Performance Summary DBA AWR System Wait Event Summary DBA AWR System Metrics Summary
Blitz Report In Action
Blitz Report™

Blitz Report™ provides multiple benefits: