Psycopg 3 -- PostgreSQL database adapter for Python

Psycopg 3 is a modern implementation of a PostgreSQL adapter for Python.

Installation

Quick version::

pip install --upgrade pip               # upgrade pip to at least 20.3
pip install "psycopg[binary,pool]"      # install binary dependencies

For further information about installation please check the documentation__.

.. __: https://www.psycopg.org/psycopg3/docs/basic/install.html

Hacking

In order to work on the Psycopg source code you need to have the libpq PostgreSQL client library installed in the system. For instance, on Debian systems, you can obtain it by running::

sudo apt install libpq5

After which you can clone this repository::

git clone https://github.com/psycopg/psycopg.git
cd psycopg

Please note that the repository contains the source code of several Python packages: that's why you don't see a setup.py here. The packages may have different requirements:

• The psycopg directory contains the pure python implementation of psycopg. The package has only a runtime dependency on the libpq, the PostgreSQL client library, which should be installed in your system.

• The psycopg_c directory contains an optimization module written in C/Cython. In order to build it you will need a few development tools: please look at Local installation__ in the docs for the details.

  .. __: https://www.psycopg.org/psycopg3/docs/basic/install.html#local-installation

• The psycopg_pool directory contains the connection pools__ implementations. This is kept as a separate package to allow a different release cycle.

  .. __: https://www.psycopg.org/psycopg3/docs/advanced/pool.html

You can create a local virtualenv and install there the packages in development mode__, together with their development and testing requirements::

python -m venv .venv
source .venv/bin/activate
pip install -e "./psycopg[dev,test]"    # for the base Python package
pip install -e ./psycopg_c              # for the C extension module
pip install -e ./psycopg_pool           # for the connection pool

.. __: https://pip.pypa.io/en/stable/reference/pip_install/#install-editable

Now hack away! You can use tox to validate the code::

pip install tox
tox -p4

and to run the tests::

psql -c 'create database psycopg_test'
export PSYCOPG_TEST_DSN="dbname=psycopg_test"
tox -c psycopg -s
tox -c psycopg_c -s

Please look at the commands definitions in the tox.ini files if you want to run some of them interactively: the dependency should be already in your virtualenv. Feel free to adapt these recipes if you follow a different development pattern.