Clean WRH$_ACTIVE_SESSION_HISTORY in SYSAUX

Tablespace SYSAUX grows quickly. Run Oracle script awrinfo.sql to find what is using the space. One section of the report shows that ACTIVE_SESSION_HISTORY is the biggest consumer.

SQL> @$ORACLE_HOME/rdbms/admin/awrinfo.sql

COMPONENT MB    SEGMENT_NAME           - % SPACE_USED SEGMENT_TYPE
--------- ----- ------------------------------ -------------- ---------------

ASH       408.0 WRH$_ACTIVE_SESSION_HISTORY    -  98%         TABLE PARTITION
                .WRH$_ACTIVE_21536658_7139e
ASH        41.0 WRH$_ACTIVE_SESSION_HISTORY_PK -  98%         INDEX PARTITION
                .WRH$_ACTIVE_21536658_7139
FIXED      36.0 WRH$_SYSMETRIC_HISTORY         -  98%         TABLE
FIXED      26.0 WRH$_SYSMETRIC_HISTORY_INDEX   -  98%         INDEX

--
-- Check the Snapshot retention, it works fine (only 8 snapshots exist).
--
SQL> SELECT snap_interval, retention, most_recent_purge_time
    FROM sys.wrm$_wr_control;

SNAP_INTERVAL     RETENTION         MOST_RECENT_PURGE_TIME
----------------- ----------------- -------------------------
+00000 01:00:00.0 +00007 00:00:00.0 27-NOV-13 12.06.06.995 AM

SQL> select dbid, count(*) from SYS.WRM$_SNAPSHOT group by dbid;

      DBID   COUNT(*)
---------- ----------
  21536658          8

-- One interesting thing is DBA_HIST_SNAPSHOT and SYS.WRM$_SNAPSHOT are different
SQL> select * from DBA_HIST_SNAPSHOT;

no rows selected

--
-- Run below query to identify the big tables in SYSAUX
--
SQL> SELECT *
      FROM (  SELECT bytes / 1024 / 1024 dim_Mb, segment_name, segment_type
                FROM dba_segments
               WHERE tablespace_name = 'SYSAUX'
            ORDER BY dim_Mb DESC)
     WHERE ROWNUM < 5;

    DIM_MB SEGMENT_NAME                   SEGMENT_TYPE
---------- ------------------------------ ------------
       544 WRH$_ACTIVE_SESSION_HISTORY    TABLE PARTITION
       128 I_WRI$_OPTSTAT_H_OBJ#_ICOL#_ST INDEX
        88 WRI$_OPTSTAT_HISTGRM_HISTORY   TABLE
        64 WRH$_SYSMETRIC_HISTORY         TABLE

--
-- Follow Oracle DOC ID 387914.1 to clean table WRH$_ACTIVE_SESSION_HISTORY
--
SQL> select table_name,partition_name
  2  from dba_tab_partitions
  3  where table_name = 'WRH$_ACTIVE_SESSION_HISTORY';

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7139
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_SES_MXDB_MXSN

SQL> select count(*) from WRH$_ACTIVE_SESSION_HISTORY;

  COUNT(*)
----------
   1653076

SQL> alter session set "_swrf_test_action" = 72;

Session altered.

SQL>
set serveroutput on
declare
CURSOR cur_part IS
SELECT partition_name from dba_tab_partitions
WHERE table_name = 'WRH$_ACTIVE_SESSION_HISTORY'; 

query1 varchar2(200);
query2 varchar2(200); 

TYPE partrec IS RECORD (snapid number, dbid number);
TYPE partlist IS TABLE OF partrec; 

Outlist partlist;
begin
dbms_output.put_line('PARTITION NAME SNAP_ID DBID');
dbms_output.put_line('--------------------------- ------- ----------'); 

for part in cur_part loop
query1 := 'select min(snap_id), dbid from 
sys.WRH$_ACTIVE_SESSION_HISTORY partition ('||part.partition_name||') group by dbid';
execute immediate query1 bulk collect into OutList; 

if OutList.count > 0 then
for i in OutList.first..OutList.last loop
dbms_output.put_line(part.partition_name||' Min '||OutList(i).snapid||' '||OutList(i).dbid);
end loop;
end if; 

query2 := 'select max(snap_id), dbid 
from sys.WRH$_ACTIVE_SESSION_HISTORY partition ('||part.partition_name||') group by dbid';
execute immediate query2 bulk collect into OutList; 

if OutList.count > 0 then
for i in OutList.first..OutList.last loop
dbms_output.put_line(part.partition_name||' Max '||OutList(i).snapid||' '||OutList(i).dbid);
dbms_output.put_line('---');
end loop;
end if; 

end loop;
end;
/

PARTITION NAME                SNAP_ID DBID
----------------------------- ------- ----------
WRH$_ACTIVE_21536658_7139 Min 7139    21536658
WRH$_ACTIVE_21536658_7139 Max 7881    21536658
---

PL/SQL procedure successfully completed.

-- After above PL/SQL block ran, it became three partitions
SQL> select table_name,partition_name
      from dba_tab_partitions
     where table_name = 'WRH$_ACTIVE_SESSION_HISTORY';

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7139
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7884
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_SES_MXDB_MXSN

-- Run drop Procedure
SQL> exec DBMS_WORKLOAD_REPOSITORY.DROP_SNAPSHOT_RANGE(low_snap_id =>7139,high_snap_id =>7881);

PL/SQL procedure successfully completed.

-- Now, WRH$_ACTIVE_SESSION_HISTORY has no rows
SQL> select count(*) from WRH$_ACTIVE_SESSION_HISTORY;

  COUNT(*)
----------
         0

SQL> SELECT *
      FROM (  SELECT bytes / 1024 / 1024 dim_Mb, segment_name, segment_type
                FROM dba_segments
               WHERE tablespace_name = 'SYSAUX'
            ORDER BY dim_Mb DESC)
     WHERE ROWNUM < 5;  

    DIM_MB SEGMENT_NAME                   SEGMENT_TYPE
---------- ------------------------------ -----------
       128 I_WRI$_OPTSTAT_H_OBJ#_ICOL#_ST INDEX
        88 WRI$_OPTSTAT_HISTGRM_HISTORY   TABLE
        64 WRH$_SYSMETRIC_HISTORY         TABLE
        55 I_WRI$_OPTSTAT_H_ST            INDEX

-- But partitions were NOT dropped
SQL> select table_name,partition_name
     from dba_tab_partitions
     where table_name = 'WRH$_ACTIVE_SESSION_HISTORY';

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7139
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7884
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_SES_MXDB_MXSN

--
-- Follow DOC ID 287679.1 to shrink the tablespace
--
SQL> SELECT COUNT(1) Orphaned_ASH_Rows
    FROM wrh$_active_session_history a
    WHERE NOT EXISTS
      (SELECT 1
      FROM wrm$_snapshot
      WHERE snap_id       = a.snap_id
      AND dbid            = a.dbid
      AND instance_number = a.instance_number
      );

ORPHANED_ASH_ROWS
-----------------
                0

-- To reclaim the freed space (since row movement is enabled on WRH$_ACTIVE_SESSION_HISTORY by default)
SQL> alter table WRH$_ACTIVE_SESSION_HISTORY shrink space;

Table altered.

SQL> column OCCUPANT_NAME format a15
SQL> SELECT occupant_name,
      occupant_desc,
      space_usage_kbytes
    FROM v$sysaux_occupants
    WHERE occupant_name LIKE '%AWR%';

OCCUPANT_NAME OCCUPANT_DESC                                          SPACE_USAGE_KBYTES
------------- ------------------------------------------------------ ------------------
SM/AWR        Server Manageability - Automatic Workload Repository   300416

--
-- Check again after a few days:
-- It seems the old partition was dropped automatically and a new one was created.
SQL> select table_name,partition_name
     from dba_tab_partitions
     where table_name = 'WRH$_ACTIVE_SESSION_HISTORY'; 

TABLE_NAME                     PARTITION_NAME
------------------------------ ------------------------------
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_21536658_7885
WRH$_ACTIVE_SESSION_HISTORY    WRH$_ACTIVE_SES_MXDB_MXSN

-- And new entries are written into table WRH$_ACTIVE_SESSION_HISTORY
SQL> select count(*) from WRH$_ACTIVE_SESSION_HISTORY;

  COUNT(*)
----------
     31569

-- while the Snapshot retention keeps unchanged.
SQL> SELECT snap_interval, retention, most_recent_purge_time
    FROM sys.wrm$_wr_control;

SNAP_INTERVAL     RETENTION         MOST_RECENT_PURGE_TIME
----------------- ----------------- -------------------------
+00000 01:00:00.0 +00007 00:00:00.0 11-DEC-13 12.00.29.165 AM