Currently, it is not possible to store 3rd party reports in archive tables (at least w/o some large hacks) due to this one optimization: https://github.com/piwik/piwik/blob/master/core/ArchiveProcessor/Loader.php#L121

If there are no visits for a period, the Archiver code for a plugin will not be launched. For plugins that only provide 3rd party data, there will never be visits in the log_visit table, so the archiver will never be launched.

To fix this for our LTS version, we can add an event that specifies idSites for whom this optimization should be skipped. This will allow many more plugins to be created for 2.15, while we work on 3.0.

Potential names for the new event include:

• Archiver.getIdSitesNotUsingLogTables
• Archiver.getIdSitesDisplayingThirdPartyData
• Archver.getIdSitesDisplayingNonPiwikData