pg_create_subscriber

Initialize a new logical subscriber from a physical replica or base backup. This tool is based on pglogical_create_subscriber but adapted to use the builtin Logical Replication insted of the pglogical extension.

Supported PostgreSQL versions

The aim of the project is support as many community-supported major versions of Postgres as possible. Currently, the following versions of PostgreSQL are supported:

10, 11, 12 and 13.

Installation from source code

Source code installs are the same as for any other PostgreSQL extension built using PGXS.

Make sure the directory containing pg_config from the PostgreSQL release is listed in your PATH environment variable. You might have to install a -dev or -devel package for your PostgreSQL release from your package manager if you don't have pg_config.

Then run make to compile, and make install to install. You might need to use sudo for the install step.

e.g. for a typical Fedora or RHEL 7 install, assuming you're using the yum.postgresql.org packages for PostgreSQL:

$ sudo dnf install postgresql13-devel
$ git clone https://github.com/fabriziomello/pg_create_subscriber.git
$ cd pg_create_subscriber
$ PATH=/usr/pgsql-13/bin:$PATH
$ USE_PGXS=1 make
$ USE_PGXS=1 make install

Usage

$ pg_create_subscriber --help
pg_create_subscriber create new logical subscriber from basebackup of provider.

Usage:
  pg_create_subscriber [OPTION]...

General options:
  -D, --pgdata=DIRECTORY            data directory to be used for new node,
                                    can be either empty/non-existing directory,
                                    or directory populated using
                                    pg_basebackup -X stream command
  --databases                       optional list of databases to replicate
  -n, --subscriber-name=NAME        name of the newly created subscrber
  --subscriber-dsn=CONNSTR          connection string to the newly created subscriber
  --provider-dsn=CONNSTR            connection string to the provider
  --publication-names=PUBLICATIONS  comma separated list of publication names
  --drop-slot-if-exists             drop replication slot of conflicting name
  -s, --stop                        stop the server once the initialization is done
  -v                                increase logging verbosity
  --extra-basebackup-args           additional arguments to pass to pg_basebackup.
                                    Safe options: -T, -c, --xlogdir/--waldir

Configuration files override:
  --hba-conf              path to the new pg_hba.conf
  --postgresql-conf       path to the new postgresql.conf
  --recovery-conf         path to the template recovery configuration

Example

Before start you should setup two PostgreSQL nodes using Streaming Replication. One node will be the master.node and another replica.node.

1. Create publication on master.node

CREATE PUBLICATION pub_test FOR ALL TABLES;

2. Stop the replica.node

systemctl stop postgresql-13

3. Execute pg_create_subscriber over the stopped replica.node

pg_create_subscriber --pgdata=/var/lib/pgsql/13/data --stop -v \
  --databases=fabrizio --subscriber-name=sub_test --publication-names='pub_test' \
  --subscriber-dsn='host=replica.node user=postgres port=5432' \
  --provider-dsn='host=master.node user=postgres port=5432'

4. Start the new replica node

systemctl start postgresql-13

Please feel free to open a PR.

Authors

• Fabrízio de Royes Mello

Funding

All this work was only possible with the funding and support of OnGres.

Credits

Thanks to all my OnGres colleagues for support and testing.

Thanks to my friend Martín Marqués for the awesome webinar Highway to Zero Downtime PostgreSQL Upgrades that gave me the ideas to finish this tool.

License

PostgreSQL server source code, used under the PostgreSQL license.
Portions Copyright (c) 1996-2021, The PostgreSQL Global Development Group
Portions Copyright (c) 1994, The Regents of the University of California

All other parts are licensed under the 3-clause BSD license, see LICENSE file for details.
Copyright (c) 2021, Fabrízio de Royes Mello fabriziomello@gmail.com