Documentation for item preprocessing is lacking documentation of specifics for throttling preprocessing steps.

The most obvious specifics are:

• Discarded value is not saved in database and Zabbix server has no knowledge that this value was received.
• If value is discarded, no trigger expressions will be checked, as a result, no problems for related triggers will be created or resolved.
• Trigger functions will work only based on data that is actually saved in database.
• As trends are built based on data in database, if there will be no value saved for an hour then there will also be no trends data for that hour.