Our goal is to create a new open source plugin that will let Super Users easily invalidate any report in Piwik. This will provide a user friendly way to make this frequent action.

Proposal

• add a new menu entry in Administration > Invalidate reports (maybe there's a better location?)
• the menu entry and functionality is only available to Super Users (since it can result in rather big performance issues if someone invalidates a very big long range on a large piwik DB)
• the page displays:
  • Title Invalidate historical reports
  • Description:

You can invalidate all historical reports for a specific website, or for all websites, by clicking the button "Invalidate historical reports". When you invalidate historical reports, they will be re-processed from the raw logs the next time archiving will run. This is useful when you want to force Piwik to re-process historical data for all reports, for example when:

• you created a new Custom Report and want the Custom Reports to be processed for all historical data
• you created a new Funnel and want your Funnel reports to be processed for all historical data
• you have modified the raw visitor information (for example by importing new visitor logs in the past) and want these changes to raw logs reflected in all your reports.

• Website selector (would default on "All websites" maybe?) and segment editor.
• a button "Invalidate all historical reports"
• on click on the button, display a popover:

You are about to invalidate all historical reports, which will cause Piwik to re-process all historical reports the next time archiving run. Re-processing all historical reports may take a long time. Are you sure you want to invalidate all historical reports for [website $WebsiteName|All websites]?

• if a segment was also selected, also append and for segment $segmentName
• when no segment was selected, append and for all Segments.
• on submit:
  • the API CoreAdminHome.invalidateArchivedReports is called with those parameters that user confirmed
  • For the date parameter, we can use $websiteCreationTime,today to invalidate all reports (method getCreationDateFor)
  • If "All websites" was selected, we can use $earliestWebsiteCreationTime,today to invalidate all reports (use method getMinMaxDateAcrossWebsites)
  • we set period to false so that all periods are invalidated
  • on successful submit, write a message such as:

Reports have been successfully invalidated. These reports will be reprocessed the next time reports archiving will run.
The CoreAdminHome.invalidateArchivedReports API returned:
$API_OUTPUT_HERE

• ideally include a UI test for the initial page load, and for the page after successful submit of an invalidation
• Update FAQ: https://piwik.org/faq/how-to/faq_155/ to link to this new plugin as an alternative to the API solution
• host plugin at piwik/plugin-InvalidateReports or so

Notes

• Refs: How do I record tracking data in the past, and tell Piwik to invalidate and re-process the past reports?
• Follows up: invalidateArchivedReports API can invalidate report data for a particular '&segment=' #8858 New Command 'core:invalidate-report-data' to invalidate archive data (w/ period cascading) #8825