UNDO RETENTION GUARANTEE ESTADISTICAS CONFIGURACION

SQL>show parameter undo_retention;

select to_char(begin_time, 'DD-MON-RR HH24:MI') begin_time,
to_char(end_time, 'DD-MON-RR HH24:MI') end_time, tuned_undoretention
from v$undostat order by end_time;

BEGIN_TIME      END_TIME        TUNED_UNDORETENTION
--------------- --------------- -------------------
04-FEB-05 00:01 04-FEB-05 00:11               12100
      ...                                          
07-FEB-05 23:21 07-FEB-05 23:31               86700
07-FEB-05 23:31 07-FEB-05 23:41               86700
07-FEB-05 23:41 07-FEB-05 23:51               86700
07-FEB-05 23:51 07-FEB-05 23:52               86700

576 rows selected.

SQL>alter tablespace undotbs1 retention guarantee

SQL>alter tablespace undotbs1 retention noguarantee

-- Guarantee the minimum threshold is maintained.
ALTER TABLESPACE undotbs1 RETENTION GUARANTEE;

SELECT tablespace_name, retention FROM dba_tablespaces;

TABLESPACE_NAME                RETENTION
------------------------------ -----------
SYSTEM                         NOT APPLY
UNDOTBS1                       GUARANTEE
SYSAUX                         NOT APPLY
TEMP                           NOT APPLY
USERS                          NOT APPLY

5 rows selected.

-- Switch back to the default mode.
ALTER TABLESPACE undotbs1 RETENTION NOGUARANTEE;
SQL> select tablespace_name,retention from dba_tablespaces;

TABLESPACE_NAME 	       RETENTION
------------------------------ -----------
SYSTEM			       NOT APPLY
SYSAUX			       NOT APPLY
UNDOTBS1		       NOGUARANTEE
TEMP			       NOT APPLY
USERS			       NOT APPLY
EXAMPLE 		       NOT APPLY
DATOS			       NOT APPLY

7 rows selected.

SQL> alter tablespace undotbs1 retention guarantee;

Tablespace altered.

SQL> select tablespace_name,retention from dba_tablespaces;

TABLESPACE_NAME 	       RETENTION
------------------------------ -----------
SYSTEM			       NOT APPLY
SYSAUX			       NOT APPLY
UNDOTBS1		       GUARANTEE
TEMP			       NOT APPLY
USERS			       NOT APPLY
EXAMPLE 		       NOT APPLY
DATOS			       NOT APPLY

7 rows selected.
SQL> ALTER SYSTEM SET TEMP_UNDO_ENABLED=TRUE;

V$TEMPUNDOSTAT;

SELECT TO_CHAR(BEGIN_TIME, 'MM/DD/YYYY HH24:MI:SS') BEGIN_TIME,
TO_CHAR(END_TIME, 'MM/DD/YYYY HH24:MI:SS') END_TIME,
UNDOTSN, UNDOBLKCNT, MAXCONCURRENCY
FROM V$TEMPUNDOSTAT;