DEV.DBUSER(DBUSER)=>INSERT INTO prod..emp SELECT * FROM newusers;
Cross Database Access not supported for this type of command."

##</code><code>##

(Pg 9.5devel, HEAD dcbf5948e12a)

$ psql -d testdb
psql (9.5devel)
Type "help" for help.

testdb=# create table t(c text);
CREATE TABLE

testdb=# insert into t values ('value 1');
INSERT 0 1

testdb=# insert into test.public.t values ('value 3');
ERROR:  cross-database references are not implemented: "test.public.t"
LINE 1: insert into test.public.t values ('value 2');