Database Migration ERD

Readable ER diagrams from database migration SQL. No database connection required.

64 dummy tables, six automatically inferred groups, default settings. Before/after and tool comparison · Download SVG

Why use it?

• Layout for larger schemas: automatic groups and colours, measured cluster packing, and cross-group FK routing. Built on D2 + ELK; optional TALA.
• Useful table detail: column types, composite keys, self references and index descriptions below tables. Add missing relationships with YAML.
• Migration-aware input: forward SQL changes, sql-migrate/goose Up sections and supported dollar-quoted DO blocks, processed locally without executing SQL.
• Fits codegen and CI: one command, SVG-only output by default, meaningful exit codes and previous SVG preserved on failure.

SQL support: the parser currently uses the PostgreSQL dialect. Compatible SQL from other databases may work, but full MySQL, SQLite and SQL Server migration support is not verified. It reads SQL files, not ORM migration code, and never applies migrations. See supported SQL and limitations.

Install

Requires Python 3.11+, pipx and D2 0.7.1 on PATH. Install the versioned package from GitHub Releases:

pipx install https://github.com/fightingBald/database-migration-erd/releases/download/v0.2.1/migration_erd-0.2.1-py3-none-any.whl

Usage

Pass the migration directory and output SVG:

migration-erd ./migrations ./generated/schema.svg

Supply the complete migration history. The command creates only schema.svg; open it in a browser. Grouping, colours and column types are enabled by default.

Errors appear in the terminal, with a nonzero exit code and the previous SVG preserved. No log files are written by default.

Option	Purpose
--fk-config file.yaml	Add relationships.
--layout-config file.yaml	Set groups, titles and colours.
--layout tala	Use TALA.
--show-references	Label cross-group FK targets beside fields.

Run migration-erd --help for all options. The developer guide covers source installation, copying into tools/erd-generator/, CI and development. python -m erd_generator remains available.

Found a parsing or layout problem? Report it with a small fictional SQL example.