Thank you for your help Alvaro - we really appreciate it. The error in fact stopped this morning - we took downtime and ran a vacuum across all of our tables, and saw increased auto vacuum activity as well.
It looks like it bumped up the oldest multitxid to something other than 1 now: postgres@site-db01a:~ $ /usr/pgsql-9.4/bin/pg_controldata /var/lib/pgsql/cmates/data | grep -i multi Latest checkpoint's NextMultiXactId: 785051 Latest checkpoint's NextMultiOffset: 1446371 Latest checkpoint's oldestMultiXid: 575211 Latest checkpoint's oldestMulti's DB: 12998 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general