dbmt

dbmt is a simple PostgreSQL database migration tool written in Python. It helps you manage database migrations, including applying new migrations and rolling back the last applied migration.

Features

• Apply new migrations
• Rollback the last applied migration
• Keep track of applied migrations

Requirements

• Python 3.x

Installation

This package is not uploaded to PyPi but can be installed from this repository's URL in the following ways:

Using pip

Install directly from the command line using pip, like so:

pip install git+https://github.com/trizko/dbmt

Or by adding it to your requirements.txt:

dbmt @ git+https://github.com/trizko/dbmt

Using poetry

With poetry, you can install by adding the following to your pyproject.toml:

[tool.poetry.dependencies]
dbmt = { git = "https://github.com/trizko/dbmt.git" }

Usage

Subcommands

• up: Apply new migrations.
• down: Rollback the last applied migration.

Command-line Arguments

• --db-url: The PostgreSQL database URL (required).
• --migrations-dir: The directory containing migration files (default: migrations).

Migration file naming

When creating migration files, consider the following rules of how these files are applied during upgrades and downgrades:

• Migration files are applied in alphanumerical order. It is recommended that they use a number prefix and a descriptive name for the migration, e.g. 001_initial.sql, 002_add_users_table.sql, etc.
• The downgrade files should have the same number prefix and description as the upgrade files, followed by the _down suffix, e.g. 001_initial_down.sql, 002_add_users_table_down.sql, etc. These files will only be used during downgrades.

Examples

Applying Migrations

To apply all pending migrations:

dbmt up --db-url postgres://user:password@localhost:5432/your_db_name --migrations-dir migrations

Rolling Back the Last Migration

To rollback the last applied migration:

dbmt down --db-url postgres://user:password@localhost:5432/your_db_name --migrations-dir migrations

Migration Files

Create your migration files in the specified migrations directory. Use a consistent naming convention, such as 001_initial.sql, 002_add_users_table.sql, etc.

Each migration file should contain valid SQL commands for the migration. For example:

001_initial.sql

CREATE TABLE example (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL
);

001_initial_down.sql

DROP TABLE example;

002_add_users_table.sql

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username TEXT NOT NULL,
    password TEXT NOT NULL
);

002_add_users_table_down.sql

DROP TABLE users;

Contributing

Contributions are welcome. Please submit a pull request or open an issue to discuss any changes.

License

This project is licensed under the MIT License. See the LICENSE file for details.