By the way in the initial discussion on parallel infrastructure https://www.postgresql.org/message-id/20150208002027.GH9201%40alap3.anarazel.de I've seen a proposal to set the worker's PGXACT->xmin to be the minimum of the top transaction id and the snapshots.
-- Best regards, Pavel Borisov Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>
