I'm looking into this... from my understanding post_visid_high/low shouldn't be null... but since I don't see our raw data (that's more the engineering team) I need to confirm a few things first...
My initial thought is that maybe the rows with null values are from rows that have been marked as exclusion values (why set a user identifier from content which shouldn't factor into your reporting?)
https://experienceleague.adobe.com/docs/analytics/export/analytics-data-feed/data-feed-contents/datafeeds-reference.html?lang=en
exclude_hit |
Flag indicating that the hit is excluded from reporting. The visit_num column is not incremented for excluded hits. 1: Not used. Part of a scrapped feature. 2: Not used. Part of a scrapped feature. 3: No longer used. User agent exclusion 4: Exclusion based on IP address 5: Vital hit info missing, such as page_url, pagename, page_event, or event_list 6: JavaScript did not correctly process hit 7: Account-specific exclusion, such as in a VISTA rules 8: Not used. Alternate account-specific exclusion. 9: Not used. Part of a scrapped feature. 10: Invalid currency code 11: Hit missing a timestamp on a timestamp-only report suite, or a hit contained a timestamp on a non-timestamp report suite 12: Not used. Part of a scrapped feature. 13: Not used. Part of a scrapped feature. 14: Target hit that did not match up with an Analytics hit 15: Not currently used. 16: Advertising Cloud hit that did not match up to an Analytics hit |
However, like I said, I am going to look more specifically at our data to see if I can find any instances and get back to you.