Database Design

Overview

Haztrak depends on a relational database to persist its user data as well as information synced with (pulled from) RCRAInfo. RCRAInfo/e-Manifest should always be treated as the source of truth, however, the database provides users the means to, for example, draft or update electronic manifests without submitting the changes to RCRAInfo immediately.

The database schema is maintained in version control via a series of 'migration' scripts. This also enables haztrak to initiate a new database and scaffold the expected schema quickly and consistently for local development, testing, and backup.

The Haztrak project currently utilizes PostgreSQL, a widely used open-source object-relational database system known for reliability and performance.

Notes on generating the ERD

We use the pygraphviz python library and the django-extensions reusable Django app to generate the above entity relationship diagram (ERD).

Installing Header Files

This library doesn't come with pre-compiled wheels, so you'll need to install the C header files.

Fedora/RHEL

dnf install python3-devel graphviz-devel

Ubuntu/Debian

apt-get install libpython3-dev libgraphviz-dev

after installing the necessary header files, install the pygraphviz package from PyPI.

pip install pygraphviz

Generate the ERD

Use the runhaz.sh shell script to (re)generate the ERD. It applies some default flags to the pygraphviv command to constrain and style the ERD to fit our documentation needs.

Use ./runhaz.sh -h for help.

./runhaz.sh -e