Evar empty but Post_Evar doesn't in Adobe Data Feeds.

[alvaroP]

Hello everyone.
I am working with Adobe Data Feeds and I have found a very curious thing:

• I have a custom evar (evar58) where we store the Pathname URL. That variable is populated with the page being navigated to.
• My doubt arises because in my SQL Query ,is appearing during an empty evar58 (as if it did not modify) but the post_evar58 changes between a hit and another, without the evar58 changing.

select post_visid_high||post_visid_low||visit_num||visit_start_time_gmt as visit_id,evar58 , post_evar58, date_time
from adobe_datafeeds
where
reference_date >= date('2022-09-01') and reference_date <= date('2022-09-01')
and exclude_hit = '0'
and hit_source not in (5,7,8,9) 
order by date_time asc

How could be post_evar is modified and the Evar is not modified? I assume that post_evar is automatically populated by Adobe, but based in the evar value. Could anybody clarify me this?

In addition, could be the opposite thing? Evar value that is not populated to post_evar?

[Jennifer_Dungan · Accepted solution]

So interesting fact... "Processing Rules" apply only to the post_ values... if you are using Processing Rules to modify your eVar58 value, that could easily explain the behaviour.

This is why in Mobile App implementations that use Processing Rules to map context variables to props and eVars, that there is no data at all in the "base" dimensions but has values in the post_ version of those values....

It's also possible that your suite may have VISTA rules in place (Adobe making modifications on your behalf), but since those come with additional costs, the most likely scenario is your Processing Rules....