---
title: "Migrations"
description: "Learn how to create and manage database migrations in your application."
publishedAt: 2024-04-11
order: 1
status: "published"
---

> **Note:** This is mock/placeholder content for demonstration purposes.

Database migrations allow you to version control your database schema changes and apply them consistently across environments.

## Creating a Migration

To create a new migration, use the following command:

```bash
pnpm --filter web supabase:db:diff
```

This will generate a new migration file in the `apps/web/supabase/migrations` directory based on the differences between your local database and the schema files.

## Applying Migrations

To apply migrations to your local database:

```bash
pnpm --filter web supabase migrations up
```

## Migration Best Practices

1. **Always test migrations locally first** before applying to production
2. **Make migrations reversible** when possible by including DOWN statements
3. **Use transactions** to ensure atomic operations
4. **Add indexes** for foreign keys and frequently queried columns
5. **Include RLS policies** in the same migration as table creation

## Example Migration

```sql
-- Create a new table
CREATE TABLE tasks (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  account_id UUID NOT NULL REFERENCES accounts(id) ON DELETE CASCADE,
  title TEXT NOT NULL,
  completed BOOLEAN DEFAULT false,
  created_at TIMESTAMPTZ DEFAULT now()
);

-- Add RLS
ALTER TABLE tasks ENABLE ROW LEVEL SECURITY;

-- Create policies
CREATE POLICY "Users can view their account tasks"
  ON tasks FOR SELECT
  USING (account_id IN (SELECT get_user_accounts(auth.uid())));
```

## Resetting the Database

To completely reset your local database with the latest schema:

```bash
pnpm supabase:web:reset
```

This will drop all tables and reapply all migrations from scratch.