Alarm Detection

During the running of the MogDB, error scenarios can be detected and informed to users in time.

enable_alarm

Parameter description: Specifies whether to enable the alarm detection thread to detect fault scenarios that may occur in the database.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: Boolean

• on indicates that the alarm detection thread is enabled.
• off indicates that the alarm detection thread is disabled.

Default value: on

connection_alarm_rate

Parameter description: Specifies the ratio restriction on the maximum number of allowed parallel connections to the database. The maximum number of concurrent connections to the database is max_connections x connection_alarm_rate.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: a floating point number ranging from 0.0 to 1.0

Default value: 0.9

alarm_report_interval

Parameter description: specifies the interval at which an alarm is reported.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: an integer. The unit is s.

Default value: 10

alarm_component

Parameter description: Certain alarms are suppressed during alarm reporting. That is, the same alarm will not be repeatedly reported by an instance within the period specified by alarm_report_interval. Its default value is 10s. In this case, the parameter specifies the location of the alarm component that is used to process alarm information.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: a string

Default value: /opt/snas/bin/snas_cm_cmd

table_skewness_warning_threshold

Parameter description: Specifies the threshold for triggering a table skew alarm.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: a floating point number ranging from 0 to 1

Default value: 1

table_skewness_warning_rows

Parameter description: Specifies the minimum number of rows for triggering a table skew alarm.

This parameter is a USERSET parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: an integer ranging from 0 to INT_MAX

Default value: 100000