What are all possible values of the refr_medium field?

We sometimes get the following question:

What are all possible values of the refr_medium field?

The possible values are:

  • NULL
  • internal
  • social
  • search
  • email
  • unknown

It’s NULL when the page view has no referrer.

It’s set to internal when the page URL and referrer URL have the same host, or when the referring domain is configured as internal: https://github.com/snowplow/snowplow/blob/master/3-enrich/config/enrichments/referer_parser.json

The other values are parsed according to the data in our referer-parsing project: https://github.com/snowplow/referer-parser/blob/master/resources/referers.yml

To find out which referrer mediums are most common, run:

FROM atomic.events

If there’s something missing from the referrers YAML file you can also edit that file, it’s in a relatively simple indented/hierarchical format - https://github.com/snowplow/referer-parser/blob/master/resources/referers.yml and submit a pull request if there’s an additional referrer that you think others would benefit from having defined.

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I check the yml file above, for the following domains, they are classified as ‘paid’ medium:


But in my record it’s able to identify the source correctly (Outbrain and Taboola), but the medium is identified as ‘unknown’ instead of ‘paid’.

Is this a normal behavior?

Thank you.

The latest version of the referers.yml is not in Snowplow enrichment yet. It uses an older version of this file before paid media were added.

Since those sites aren’t in the yaml, they will just be grouped into unknown.

I’ll raise internal ticket to check if/why the updated file is not hosted.

Cheers @ihor - I believe they’re looking at decoupling the yaml source from the enrichment pipeline as part of the next release:

This will mean anyone can use whatever version of the referer yaml they like (e.g. including the latest version or entirely custom versions).


thanks for the explanation.

@robkingston, yes, you are absolutely right.