-- Sighting deferral (issue #103). latest_sighted_at is when a Reader's report
-- last stood in for a Poll; it is separate from latest_checked_at because the
-- six-hour ceiling has to know when the Series was last really fetched, and a
-- Sighting writing the Poll's own column would erase that.
-- latest_raised_by is attribution: whoever last raised this Series' Latest
-- Chapter by Sighting, so a Poll that contradicts the value downwards names a
-- Reader rather than flagging a row. Cleared by the Poll that judges it, NULL
-- whenever the stored value is the Poll's own.
ALTER TABLE series ADD COLUMN latest_sighted_at bigint NOT NULL DEFAULT 0;
ALTER TABLE series ADD COLUMN latest_raised_by bigint REFERENCES readers(id) ON DELETE SET NULL;