Our piwik_log_link_visit_action table has about 150 million rows in it. The time_spent and time_spent_ref_action fields use int unsigned, but the fields only ever store a maximum integer of 1799, since our visit_standard_length is 1800.
If the time_spent and time_spent_ref_action fields were changed to smallint unsigned then in theory the table would be 600 MB smaller. Would this work in practice? Would it be worth changing just on our own database, or would it be a change worth considering for Matomo in general? This would limit visit_standard_length to 65535. I wonder if anyone uses visits of more than 65535 seconds (18 hours)?