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English|日本語

migrate

A Simple Migration App

This is a simple migration application that can be executed in the console, using PostgreSQL as the database.

Prerequisites

  • This application assumes the use of PostgreSQL.
  • Database settings are managed via a .env file.
  • The application is not distributed as binary files, so you need to build it in your environment.

Environment Setup

How to Build

Execute the following in an environment where Rust is installed.

cargo build --release

Place the built executable file in your directory.

The built file will be located at the following path:

./target/release/migrate

Database Access Configuration

You will need to configure the database access information.

Follow the steps below:

  1. Place a .env file in the same directory as the built migration application.
  2. Write the database access settings in the .env file in the following format:
DATABASE_URL=postgres://username:password@hostname:port/db_name

Preliminary Steps

Creating a Table for Migration Management

First, create a table to manage the migrations.

Ensure you have a PostgreSQL environment and have set up the connection in the .env file before executing.

./migrate -i
# or
./migrate --init

After executing the command, a table named migrations will be created in the database for managing the migrations.

Creating Migration Files

Create files to define the migrations you want to execute.

./migrate -c
# or
./migrate --create

After executing the command, files like the following will be created:

# up file
./Migrations/<YYYY-MM-DD>_<UNIX_TIME_STAMP>_up.sql
# ./Migrations/2000-01-01_1234567890_up.sql

# down file
./Migrations/<YYYY-MM-DD>_<UNIX_TIME_STAMP>_down.sql
# ./Migrations/2000-01-01_1234567890_down.sql

Configuring the Migrations to Execute

Write the migrations you want to execute in the created up file and down file.

up file

Write the migrations you want to execute.

Any statement that can be executed as SQL can be written.

It is also possible to write multiple queries.

Make sure to end each SQL statement with a ;.

For example, you might write a SQL statement to create a table like this:

CREATE TABLE users (
                id BIGINT PRIMARY KEY AUTO_INCREMENT,
                username VARCHAR(255) NOT NULL,
                email VARCHAR(255) NOT NULL UNIQUE,
                password VARCHAR(255) NOT NULL,
                created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
                updated_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

down file

Write the SQL statement to rollback the results executed in the up file.

For example,

  • If you define table creation in up file, define a SQL statement to delete that table in down file.
  • If you define an insert statement in up file, define a SQL statement to delete the inserted data in down file.

In the example below, the SQL statement to delete the table defined in up file is written:

DROP TABLE users;

Executing Migrations

After completing the environment setup and preliminary steps, the migrations are executed with the following command:

./migrate

Migration Target Files

Migrations that have been executed in the past are managed in the migrations table.

If you define new migration files, only the newly added migrations will be executed.

For example:

# Execute the migration
./migrate

# Create a new migration file
./migrate --create

# Add SQL statements to the migration file
# Omitted here

# Execute the new migration
# Only the newly added migration will be executed
./migrate

Rollback

It is possible to rollback the executed migrations to a specific stage.

The command is as follows:

# <n> specifies the number of stages to rollback
./migrate -r <n>
# or
./migrate --rollback <n>

# Example
# To rollback to two stages before
./migrate -r 2
# or
./migrate --rollback 2

Also, it will only execute the possible number of rollbacks.

For a database where two migrations have been performed, specifying a number greater than 2 will only perform two rollbacks (even if 10 or 1000 is specified).

Help

If you are having trouble with the commands, refer to the help.

You can refer to the help with the following command:

./migrate -h
# or
./migrate --help

LICENSE

MIT LICENSE

AUTHOR

kip2