Michael Lewis <mlewis 'at' entrata.com> writes: > UPDATE multicards > SET defacements = COALESCE( count, 0 ) > FROM ( SELECT multicard_uid, COUNT(*) AS count FROM tickets GROUP BY multicard_uid ) AS sub > WHERE uid = multicard_uid OR multicard_uid is null; > > I expect this should work. Not sure of performance of course. This looked great but as it seems you suspected, it's very slow :/ I interrupted it after 5 minutes run on my dev computer. -- Guillaume Cottenceau