This is a question that we don't always ask, but it is important when we have a large environment and lots of users accessing Zabbix's frontend.
Most of the time, we worry only about performance so that we can meet all the VPS that Zabbix needs (tuning for writing), but we must not forget that we will have users accessing the frontend to read the data that was collected (tuning for reading).
The main point here is that we should understand our environment so that we can think about the tuning we need to perform in MySQL.
The more users we have in Zabbix, the more read operations that the database will run. For example, to access a screen that contains graphics and a map with 50 hosts participating in five groups, Zabbix needs to do the following:
Validate user permissions for each of the host groups existing in the map
Search for information about each host in the map
Search for information about the triggers and events on each host
Validate graphics permissions (host...