It appears that following SQL is reporting back historical records which are impossible to browse through a graphical user interface.

select objectid,name from events where source=0 and objectid not in (select triggerid from triggers) order by clock\G

These records are representing events which come from triggers which do not exist anymore in the instance.

Steps to reproduce:

create a new "Zabbix trapper" item with the key name "number" in host "Zabbix server"

link a trigger:

{Zabbix server:number.last()}>0

Send from the command line

zabbix_sender -z 127.0.0.1 -s "Zabbix server" -k number -o 9

Observe the trigger in problem state

Send another trap:

zabbix_sender -z 127.0.0.1 -s "Zabbix server" -k number -o 0

Observe problem is gone.

Delete trigger, leave the item.

The historical records are still in the database:

select objectid,name from events where source=0 and objectid not in (select triggerid from triggers) order by clock\G

The housekeeper does not clean these records.

Expectation:

After removing trigger in Zabbix, related events in the database must be removed too.