Overview

This package provides an Open Educational Resource (OER) to refresh prior knowledge about functional dependencies (FDs) and normalization of relational database schemata. Towards that goal, the package implements algorithms for the manipulation of functional dependencies; the package’s doc string explains the used vocabulary and contains examples.

Selected algorithms:

• FD.rminimize(): Return a minimal cover of r-minimal FDs
• FDSet.closure(): Return closure of attributes under given FDs
• FDSet.lminimize(): Return minimum subset of lhs that determines rhs
• FDSet.key(): Return a key
• FDSet.basis(): Return non-redundant r- and l-minimal basis/cover
• RelSchema.synthesize(): Normalize via synthesis into set of 3NF schemata

Installation and usage

This is Python software.

A 3NF synthesis example is available as notebook on mybinder.org; you can use that notebook in your web browser (without the need to install further software).

To normalize your own schemata, you may prefer to use the software locally. You can either clone the source repository (git clone https://gitlab.com/oer/cs/functional-dependencies.git) or install the PyPI package (pip install functional-dependencies).

The docstring for module functional_dependencies provides an introduction and several examples. See here for generated documentation.

Comments, feedback, improvements

Your feedback is highly appreciated. Feel free to open issues or merge requests in the source repository. For merge requests, make sure that pre-commit hooks are installed and run successfully as indicated next.

Side goal

Besides, the package may serve as sample Python code that respects usual coding conventions, which are checked with pre-commit hooks. The configuration file .pre-commit-config.yaml specifies test tools used here.

Origin of code

The code here is based on that file, which will not be maintained any longer.

Changelog

Changelog information is based on Keep a Changelog, where version numbers adhere to Semantic Versioning.

[Unreleased]

[1.3.0] - 2022-06-06

Added

• Optional parameter attributes in FDSet.key()

Fixed

• Previously, attributes of a relation schema were largely ignored, potentially leading to incorrect keys and synthesis results. Make sure in RelSchema.synthesize() that also attributes that do not occur in any FD are implied by the key (see doctest with nokeyschema).

[1.2.1] - 2021-01-05

Fixed

• Remove cyclic module import for doctest

[1.2.0] - 2020-12-30

Added

• Gitlab CI/CD

Changed

• Use project_urls in setup.py

[1.1.0] - 2020-12-28

Added

• Parameter minimize in RelSchema.synthesize().
• Sample notebook with 3NF example by Codd, also at mybinder.org.

Fixed

• Import in init.py.
• Project URL in docstring.
• Raw URL for coverage badge in setup.py.
• URL for REUSE badge in README.md.

[1.0.1] - 2020-12-22

Fixed

• Package URL and coverage badge in setup.py.

[1.0.0] - 2020-12-22

No change in functionality.

[1.0.0-rc.1] - 2020-12-22

Initial release. Code from there packaged for independent distribution.