Hello Hackers, At the moment one can open up a replication connection using psql and use all of the commands available on this special type of connection, except for START_REPLICATION:
$ psql -d "dbname=test replication=database" psql (9.4.1) Type "help" for help. test=# IDENTIFY_SYSTEM; systemid | timeline | xlogpos | dbname ---------------------+----------+-----------+--------- 6146106447402521313 | 1 | 0/76422B0 | bw_test (1 row) test=# START_REPLICATION SLOT test LOGICAL 0/0; unexpected PQresultStatus: 8 test=# This is due to PGRES_COPY_BOTH not being handled in psql. With introduction of logical replication I think it makes sense to support this mode, for the sake of (semi-)interactive testing from psql. For example, one could try replication from different wal positions, different output plugins and/or plugin options, w/o re-establishing the connection, interactively by editing the command directly in psql prompt, as opposed to using pg_recvlogical and editing the command line switches. I can make a patch if there's general interest for this feature. Cheers. -- Alex