hi,
i have setuped zabbix with mysql separately on two machines

number of item : 120K
Number of hosts : 500
Number of triggers : 40K
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my.cnf innodb config

1. network
   connect_timeout = 60
   wait_timeout = 28800
   max_connections = 350
   max_allowed_packet = 64M
   max_connect_errors = 1000

1. limits
   tmp_table_size = 512M
   max_heap_table_size = 256M
   table_open_cache = 512
2. innodb
   innodb_file_per_table = 1
   innodb_status_file = 1
   innodb_additional_mem_pool_size = 128M
   innodb_buffer_pool_size = 12G
   innodb_buffer_pool_instances = 12
   innodb_flush_method = O_DIRECT
   innodb_io_capacity = 2000
   innodb_flush_log_at_trx_commit = 0
   innodb_support_xa = 0
   innodb_log_file_size = 6G
   innodb_log_buffer_size = 6G
   innodb_read_io_threads = 8
   innodb_write_io_threads = 8
   innodb_old_blocks_time = 1000
   sync_binlog = 0
   query_cache_size = 0
   innodb_doublewrite = 0

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problem is
after start zabbix-server even before start [main process] and [poller] and ...
in log file have

3665:20170704:235729.617 slow query: 3.108452 sec, "select distinct t.triggerid,t.description,t.expression,t.error,t.priority,t.type,t.value,t.state,t.lastchange,t.status from hosts h,items i,functions f,triggers t where h.hostid=i.hostid and i.itemid=f.itemid and f.triggerid=t.triggerid and h.status in (0,1) and t.flags<>2"

3665:20170704:235731.383 server #0 started [main process]
.
.
.

all zabbix function is work correctly for a few minutes... then have a several slow query and you dont have any garphs but i see zabbix do all function correctly