<ADDED by zalex 2013-11-21>
Issue description below actually duplicates ZBX-6880
Read issue comments instead !
</ADDED by zalex 2013-11-21>

I'm trying to diagnose a pretty odd problem. I've re-installed everything from scratch to see if I may of done something wrong, but here is the case right now...

Clean install of 2.0.3.

1. Install & configure server A, convert to node 1
2. Install & configure server B, convert to node 2
3. Install & configure server C, convert to node 3
4. Configure node 2 => node 1, and node 3 => node 1

The odd thing is after adding about 100-200 hosts to 1, 2 and 3 I'm getting this on node 1:

8319:20121203:122014.846 [Z3005] query failed: [1452] Cannot add or update a child row: a foreign key constraint fails (`zabbix`.`alerts`, CONSTRAINT `c_alerts_2` FOREIGN KEY (`eventid`) REFERENCES `events` (`eventid`) ON DELETE CASCADE) [insert into alerts (alertid,actionid,eventid,userid,clock,mediatypeid,sendto,subject,message,status,retries,error,nextcheck,esc_step,alerttype) values (200000000005679,200100000000001,200200000042128,200100000000003,1354537208,NULL,'','[xxx] PROBLEM:12: xxx - Information - 2012.12.03 12:20:06 / 0m: 1','State:PROBLEM

8311:20121203:122115.191 [Z3005] query failed: [1452] Cannot add or update a child row: a foreign key constraint fails (`zabbix`.`alerts`, CONSTRAINT `c_alerts_2` FOREIGN KEY (`eventid`) REFERENCES `events` (`eventid`) ON DELETE CASCADE) [insert into alerts (alertid,actionid,eventid,userid,clock,mediatypeid,sendto,subject,message,status,retries,error,nextcheck,esc_step,alerttype) values (200000000005685,200100000000001,200200000042130,200100000000001,1354537271,200200000000002,'xxx','xxx RECOVERY:12: xxx - Information - 2012.12.03 12:21:06: 0','State:RECOVERY

8317:20121203:122503.363 [Z3005] query failed: [1452] Cannot add or update a child row: a foreign key constraint fails (`zabbix`.`alerts`, CONSTRAINT `c_alerts_2` FOREIGN KEY (`eventid`) REFERENCES `events` (`eventid`) ON DELETE CASCADE) [insert into alerts (alertid,actionid,eventid,userid,clock,mediatypeid,sendto,subject,message,status,retries,error,nextcheck,esc_step,alerttype) values (200000000005686,200100000000001,200200000042131,200100000000001,1354537502,200200000000002,'xxx','xxx RECOVERY:12: xxx - Average - 2012.12.03 12:24:54: 43','State:RECOVERY

8318:20121203:124443.966 [Z3005] query failed: [1452] Cannot add or update a child row: a foreign key constraint fails (`zabbix`.`alerts`, CONSTRAINT `c_alerts_2` FOREIGN KEY (`eventid`) REFERENCES `events` (`eventid`) ON DELETE CASCADE) [insert into alerts (alertid,actionid,eventid,userid,clock,mediatypeid,sendto,subject,message,status,retries,error,nextcheck,esc_step,alerttype) values (200000000005690,200100000000001,200200000042139,200100000000001,1354538681,200200000000002,'xxx','xxx RECOVERY:12: xxx - Information - 2012.12.03 12:44:36: 0','State:RECOVERY