If you want to dig deeper into the Piccolo internals, follow these instructions.

Running Cockroach

To get a local Cockroach instance running, you can use:

cockroach start-single-node --insecure --store=type=mem,size=2GiB

Make sure the test database exists:

cockroach sql --insecure
>>> create database piccolo
>>> use piccolo

Get the tests running

  • Create a new virtualenv

  • Clone the Git repo

  • cd piccolo

  • Install default dependencies: pip install -r requirements/requirements.txt

  • Install development dependencies: pip install -r requirements/dev-requirements.txt

  • Install test dependencies: pip install -r requirements/test-requirements.txt

  • Setup Postgres, and make sure a database called piccolo exists (see tests/

  • Run the automated code linting/formatting tools: ./scripts/

  • Run the test suite with Postgres: ./scripts/

  • Run the test suite with Cockroach: ./scripts/

  • Run the test suite with Sqlite: ./scripts/

Contributing to the docs

The docs are written using Sphinx. To get them running locally:

  • Install the requirements: pip install -r requirements/doc-requirements.txt

  • cd docs

  • Do an initial build of the docs: make html

  • Serve the docs: ./scripts/

  • The docs will auto rebuild as you make changes.

Code style

Piccolo uses Black for formatting, preferably with a max line length of 79, to keep it consistent with PEP8 .

You can configure VSCode by modifying settings.json as follows:

    "python.linting.enabled": true,
    "python.linting.mypyEnabled": true,
    "python.formatting.provider": "black",
    "python.formatting.blackArgs": [
    "editor.formatOnSave": true

Type hints are used throughout the project.


This isn’t required to contribute to Piccolo, but is useful when investigating performance problems.

  • Install the dependencies: pip install requirements/profile-requirements.txt

  • Make sure a Postgres database called piccolo_profile exists.

  • Run ./scripts/ to get performance data.