docs-archive/apache-airflow/2.0.0/_sources/howto/initialize-database.rst.txt

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Initializing a Database Backend
===============================

If you want to take a real test drive of Airflow, you should consider
setting up a real database backend and switching to the LocalExecutor.

Airflow was built to interact with its metadata using SqlAlchemy
with **MySQL**,  **Postgres** and **SQLite** as supported backends (SQLite is used primarily for development purpose).

.. seealso:: :ref:`Scheduler HA Database Requirements <scheduler:ha:db_requirements>` if you plan on running
   more than one scheduler

.. note:: We rely on more strict ANSI SQL settings for MySQL in order to have
   sane defaults. Make sure to have specified ``explicit_defaults_for_timestamp=1``
   in your my.cnf under ``[mysqld]``

.. note:: If you decide to use **MySQL**, we recommend using the ``mysqlclient``
   driver and specifying it in your SqlAlchemy connection string. (I.e.,
   ``mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname>``.)
   But we also support the ``mysql-connector-python`` driver (I.e.,
   ``mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname>``.) which lets you connect through SSL
   without any cert options provided. However if you want to use other drivers visit the
   `SqlAlchemy docs <https://docs.sqlalchemy.org/en/13/dialects/mysql.html>`_ for more information regarding download
   and setup of the SqlAlchemy connection.

.. note:: If you decide to use **Postgres**, we recommend using the ``psycopg2``
   driver and specifying it in your SqlAlchemy connection string. (I.e.,
   ``postgresql+psycopg2://<user>:<password>@<host>/<db>``.)
   Also note that since SqlAlchemy does not expose a way to target a
   specific schema in the Postgres connection URI, you may
   want to set a default schema for your role with a
   command similar to ``ALTER ROLE username SET search_path = airflow, foobar;``

Setup your database to host Airflow
-----------------------------------

Create a database called ``airflow`` and a database user that Airflow
will use to access this database.

Example, for **MySQL**:

.. code-block:: sql

   CREATE DATABASE airflow CHARACTER SET utf8 COLLATE utf8_unicode_ci;
   CREATE USER 'airflow' IDENTIFIED BY 'airflow';
   GRANT ALL PRIVILEGES ON airflow.* TO 'airflow';

Example, for **Postgres**:

.. code-block:: sql

   CREATE DATABASE airflow;
   CREATE USER airflow WITH PASSWORD 'airflow';
   GRANT ALL PRIVILEGES ON DATABASE airflow TO airflow;

You may need to update your Postgres ``pg_hba.conf`` to add the
``airflow`` user to the database access control list; and to reload
the database configuration to load your change. See
`The pg_hba.conf File <https://www.postgresql.org/docs/current/auth-pg-hba-conf.html>`__
in the Postgres documentation to learn more.

Configure Airflow's database connection string
----------------------------------------------

Once you have setup your database to host Airflow, you'll need to alter the
SqlAlchemy connection string located in ``sql_alchemy_conn`` option in ``[core]`` section in your configuration file
``$AIRFLOW_HOME/airflow.cfg``.

You can also define connection URI using ``AIRFLOW__CORE__SQL_ALCHEMY_CONN`` environment variable.

Configure a worker that supports parallelism
--------------------------------------------

You should then also change the ``executor`` option in the ``[core]`` option to use ``LocalExecutor``, an executor that can parallelize task instances locally.

Initialize the database
-----------------------

.. code-block:: bash

    # initialize the database
    airflow db init

.. spelling::

     hba