We used mailchimp's suggested process[1] of sending an email with an opt-in link taking them to a form with a consent checkbox. Subscribers failing to opt-in actually remain on the list for billing purposes, but without a GDPR flag set.
My task, to save costs was to remove around 8k subscribers...
I created a segment to filter using their newly created GDPR fields, but whenever that segment is used it takes several minutes to load. Cycling through the pager takes a similar time too.
There is no way to easily delete all users in this segment, There is only a select visible checkbox, not a select all checkbox, at most you can only select 100 email addresses at once. It does retain the selection if you go to the next page, but it does take a long time to do so.
Once you trigger the delete action, it adds it as a background task, this makes sense but it affects the pager in an unpredictable way, the safest way is just to wait, go back to the list screen and reapply the segment. It's easy to get stuck on a page that says there is no results when there are.
I've found the only way to do it with my list is to break the segment down so the result is less than a thousand (I started with accounts not changed in x years, then get more recent), then I go through those pages deleting those users.
It's taken me a couple of hours to delete about 3,000 so far.
Funnily enough, when using segments that don't relate to GDPR the UI is much snappier. Is this poor database optimisation for a rushed feature, or a dark UI pattern to dissuade people from using this?
Why no Select All button?, I vaguely remember them having one in the past, when I was doing research on how to handle selection of large numbers of records, but I cannot be sure about that.
[1] http://eepurl.com/dqP8Bb
