postgres.md

Using Postgres

The minimum supported version of PostgreSQL is determined by the Dependency Deprecation Policy.

Install postgres client libraries

Synapse will require the python postgres client library in order to connect to a postgres database.

• If you are using the matrix.org debian/ubuntu packages, the necessary python library will already be installed, but you will need to ensure the low-level postgres library is installed, which you can do with apt install libpq5.

• For other pre-built packages, please consult the documentation from the relevant package.

• If you installed synapse in a virtualenv, you can install the library with:

  ~/synapse/env/bin/pip install "matrix-synapse[postgres]"

  (substituting the path to your virtualenv for ~/synapse/env, if you used a different path). You will require the postgres development files. These are in the libpq-dev package on Debian-derived distributions.

Set up database

Assuming your PostgreSQL database user is called postgres, first authenticate as the database user with:

su - postgres
# Or, if your system uses sudo to get administrative rights
sudo -u postgres bash

Then, create a postgres user and a database with:

# this will prompt for a password for the new user
createuser --pwprompt synapse_user

createdb --encoding=UTF8 --locale=C --template=template0 --owner=synapse_user synapse

The above will create a user called synapse_user, and a database called synapse.

Note that the PostgreSQL database must have the correct encoding set (as shown above), otherwise it will not be able to store UTF8 strings.

You may need to enable password authentication so synapse_user can connect to the database. See https://www.postgresql.org/docs/current/auth-pg-hba-conf.html.

Synapse config

When you are ready to start using PostgreSQL, edit the database section in your config file to match the following lines:

database:
  name: psycopg2
  args:
    user: <user>
    password: <pass>
    database: <db>
    host: <host>
    cp_min: 5
    cp_max: 10

All key, values in args are passed to the psycopg2.connect(..) function, except keys beginning with cp_, which are consumed by the twisted adbapi connection pool. See the libpq documentation for a list of options which can be passed.

You should consider tuning the args.keepalives_* options if there is any danger of the connection between your homeserver and database dropping, otherwise Synapse may block for an extended period while it waits for a response from the database server. Example values might be:

database:
  args:
    # ... as above

    # seconds of inactivity after which TCP should send a keepalive message to the server
    keepalives_idle: 10

    # the number of seconds after which a TCP keepalive message that is not
    # acknowledged by the server should be retransmitted
    keepalives_interval: 10

    # the number of TCP keepalives that can be lost before the client's connection
    # to the server is considered dead
    keepalives_count: 3

Tuning Postgres