wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main 10" > /etc/apt/sources.list.d/pgdg.list'
sudo apt-get update

sudo apt install postgresql-10

# pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
10 main 5432 online postgres /var/lib/postgresql/10/main /var/log/postgresql/postgresql-10-main.log

# pg_createcluster 10 sub
Creating new PostgreSQL cluster 10/sub ...
/usr/lib/postgresql/10/bin/initdb -D /var/lib/postgresql/10/sub --auth-local peer --auth-host md5
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.UTF-8".
The default database encoding has accordingly been set to "UTF8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/postgresql/10/sub ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting dynamic shared memory implementation ... posix
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok

Success. You can now start the database server using:

/usr/lib/postgresql/10/bin/pg_ctl -D /var/lib/postgresql/10/sub -l logfile start

Ver Cluster Port Status Owner Data directory Log file
10 sub 5433 down postgres /var/lib/postgresql/10/sub /var/log/postgresql/postgresql-10-sub.log

# pg_ctlcluster 10 sub start

# pg_lsclusters
Ver Cluster Port Status Owner Data directory Log file
10 main 5432 online postgres /var/lib/postgresql/10/main /var/log/postgresql/postgresql-10-main.log
10 sub 5433 online postgres /var/lib/postgresql/10/sub /var/log/postgresql/postgresql-10-sub.log

wal_level = logical

pg_ctlcluster 10 main restart

postgres=# create database b1;
CREATE DATABASE
postgres=# \c b1
You are now connected to database "b1" as user "postgres".

b1=# create table t1 (c1 text);
CREATE TABLE
b1=# insert into t1 values ('un');
INSERT 0 1
b1=# select * from t1;
 c1
----
 un
(1 row)

b1=# CREATE PUBLICATION pub1 FOR TABLE t1 ;

b1=# \dRp+
 Publication pub1
 All tables | Inserts | Updates | Deletes
------------+---------+---------+---------
 f | t | t | t
Tables:
 "public.t1"

postgres@blog:~$ psql -p 5433
psql (10beta2)
Type "help" for help.

postgres=# CREATE DATABASE b2;
CREATE DATABASE
postgres=# \c b2
You are now connected to database "b2" as user "postgres".
b2=# create table t1 (c1 text);
CREATE TABLE

b2=# CREATE SUBSCRIPTION sub1 CONNECTION 'host=/var/run/postgresql port=5432 dbname=b1' PUBLICATION pub1;
NOTICE: created replication slot "sub1" on publisher
CREATE SUBSCRIPTION
b2=# select * from t1;
 c1
----
 un
(1 row)

postgres@blog:~$ psql b1
psql (10beta2)
Type "help" for help.

b1=# insert into t1 values ('deux');
INSERT 0 1
postgres=# \q
postgres@blog:~$ psql -p 5433 b2
psql (10beta2)
Type "help" for help.
b2=# select * from t1;
 c1
------
 un
 deux
(2 rows)

\dRs+
 List of subscriptions
 Name | Owner | Enabled | Publication | Synchronous commit | Conninfo
------+----------+---------+-------------+--------------------+----------------------------------------------
 sub1 | postgres | t | {pub1} | off | host=/var/run/postgresql port=5432 dbname=b1
(1 row)