I'm building a queuing mechanism of sorts. There are rows of data that need processing, and a status flag. I'm using an update .. returning clause to manage it:
UPDATE stuff
SET computed = 'working'
WHERE id = (SELECT id from STUFF WHERE computed IS NULL LIMIT 1)
RETURNING *
Is the nested select part the same lock as the update, or do I have a race condition here? If so, does the inner select need to be a select for update?