This results in an Assert failure on master and an elog ERROR prior to c2fe139c201:
create role test_role with login; create table ref(a int primary key); grant references on ref to test_role; set role test_role; create table t1(a int, b int); insert into t1 values(1,1); alter table t1 add constraint t1_b_key foreign key (b) references ref(a); server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request. The connection to the server was lost. Attempting reset: Failed. Fails in heapam_tuple_satisfies_snapshot() at Assert(BufferIsValid(bslot->buffer)); c2fe139c201~1: ERROR: expected buffer tuple The test case is just a variation of the case in [1], but a different bug, so reporting it on a different thread. I've not looked into the cause or when it started happening. [1] https://www.postgresql.org/message-id/CAK%3D1%3DWrnNmBbe5D9sm3t0a6dnAq3cdbF1vXY816j1wsMqzC8bw%40mail.gmail.com -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services