If you installed Matomo Analytics before Matomo 4.0, an event value might be truncated or rounded when the value is high. For example if you track a value of 12225201, the value might be stored as 12225200.

If you track high event values, you can fix this issue by running a database migration script like this:

ALTER TABLE  `matomo_log_link_visit_action` CHANGE `custom_float` `custom_float` DOUBLE NULL DEFAULT NULL;

Please note this same DB field is also used for storing other data like how long it took to load a website and running this update script may alter your existing stored custom values. For example, if previously a value of 4.1 is stored, it might convert it to 4.099999. As a result, for example a changed value might not match a specific segment anymore.

If you’re wanting to test this first, you may compare the output of this SQL query (this query may run a long time):

    SELECT custom_float, CAST(custom_float as DOUBLE) FROM matomo_log_link_visit_action WHERE custom_float is not null ORDER BY custom_float ASC LIMIT 10000

To see if any value would be changed as it depends on your MySQL version. Integers (numbers without a fraction part) should remain generally unchanged.

Previous FAQ: What are the requirements for installing Matomo?