Optimize Distributed Workload - Expert Oracle RAC Performance Diagnostics and Tuning - page 504

Valid goal types are listed in Table 15-5 .

Table 15-5. Load Balancing Goal Types

Goal Type Value Description

GOAL_NONE 0 No load-balancing goal has been defined.

GOAL_SERVICE_TIME 1 Load balancing based on the service or response time.

GOAL_THROUGHPUT 2 Load balancing based on throughput.

Defining Thresholds
Apart from defining goals for load balancing the cluster, users can define thresholds that will verify activity in the
notification service and inform the DBAs when such thresholds are reached.
Thresholds can be defined either using the OEM interface or using the PL/SQL procedures following:

SQL> exec DBMS_SERVER_ALERT.SET_THRESHOLD( -
> METRICS_ID => dbms_server_alert.elapsed_time_per_call,-
> WARNING_OPERATOR=> dbms_server_alert.operator_ge,-
> WARNING_VALUE=>'500',-
> CRITICAL_OPERATOR=>dbms_server_alert.operator_ge,-
> CRITICAL_VALUE=> '750',-
> OBSERVATION_PERIOD=> 15,-
> CONSECUTIVE_OCCURRENCES =>3,-
> OBJECT_TYPE=>dbms_server_alert.object_type_service,-
> OBJECT_NAME => 'TAPS');
PL/SQL procedure successfully completed.

The preceding definition defines a threshold on elapsed time, with a warning level of 500 seconds indicated
by the variable WARNING_VALUE and a critical value of 750 seconds indicated by the variable CRITICAL_VALUE . The
definition further stipulates that a notification should be sent only if the threshold is reached three consecutive times
(indicated by CONSECUTIVE_OCCURRENCES ), with an interval of 15 seconds apart (indicated by OBSERVATION_PERIOD ).

Threshold Verification
Load-balance definitions could be verified using the following query:

SQL> COL inst format 999
COL name format a20
SELECT inst_id INST,
name,
goal,
clb_goal,
aq_ha_notification
FROM gv$services;