The OC Home page shows the number of devices for 'Actively monitored (last 30 minutes)' and 'Total devices discovered' in the upper right pain.
How are those number obtained?
Release : 20.3
Component : UIM - CABI
This is the query used:
select * from (select 'total_device_count' as type, count(*) as device_count from cm_computer_system
union
select 'active_device_count' as type, count(DISTINCT(CASE WHEN sqs.sampletime is not NULL THEN ccs.cs_id ELSE NULL END)) as device_count
from cm_computer_system ccs
join cm_device cd
on ccs.cs_id = cd.cs_id
join cm_configuration_item cci
on cd.dev_id = cci.dev_id
join cm_configuration_item_metric ccim
on cci.ci_id = ccim.ci_id
join s_qos_data sqd
on ccim.ci_metric_id = sqd.ci_metric_id
and sqd.origin IN (select * from (select distinct sqd.origin from S_QOS_DATA sqd union select distinct ccso.origin from CM_COMPUTER_SYSTEM_ORIGIN ccso union select distinct na.origin from NAS_ALARMS na) alias)
join s_qos_snapshot sqs
on sqd.table_id = sqs.table_id
and CAST(sqs.sampletime as datetime) >= DATEADD(MINUTE, -30, CURRENT_TIMESTAMP)) src
pivot (sum(device_count) for type in (total_device_count,active_device_count))piv;