My total database size was 130 MB but after the update it reached more than 1GB overnight. Changing the "Delete old archived reports" settings and "Purge DB now" didn't do a thing.

Due to database size limitations of my host provider I deleted the piwik_archive_blob and piwik_archive_numeric tables except for the last and current months, using phpMyAdmin. The total size of database became 180 MB, more than before the update, but acceptable.

Now a day later, those deleted tables are back and are gaining size! and my database size has reached 1 GB.

Running "console core:purge-old-archive-data" and "console core:run-scheduled-tasks" didn't help at all.