-- Jobs a runner handed back (oxygenflow#76, oxygenhub#312): drained before

-- it left, or its lease lapsed. Queued again ahead of new work; NULL if it

-- never was.

ALTER TABLE flow_jobs ADD COLUMN handed_back_ms INTEGER;

-- How many times; past a few it ends as an error rather than bounce on.

ALTER TABLE flow_jobs ADD COLUMN handbacks INTEGER NOT NULL DEFAULT 0;