---
to: "migrations/001_initial_schema.sql"
vars:
  project_name: "Database Migrations with Placeholders"
  description: "Production-ready database schema with migration placeholders"
rdf_inline:
  - "@prefix ex: <https://example.com/database/> . ex:DatabaseMigration ex:implements ex:SchemaVersioning ."
sparql:
  schema_requirements: "SELECT ?table WHERE { ?table a ex:DatabaseTable }"
---

-- 🚧 PLACEHOLDER: Database Migration System
-- ID: database-migrations
-- Category: Critical
-- Priority: 8/10
-- Guidance: Automated database schema migrations with rollback capability
-- Effort: 8 hours
-- TODO: Implement this for production readiness
-- Example migration file structure

-- Migration: 001_initial_schema
-- Description: Initial database schema setup
-- Created: {{timestamp}}
-- Author: GGen Production System

-- 🚧 PLACEHOLDER: Users table with proper constraints
-- TODO: Implement users table with authentication fields
-- Guidance: Include password hashing, email uniqueness, timestamps

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TABLE statement --}}
-- TODO: Create users table
-- CREATE TABLE users (
--     user_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     email VARCHAR(255) UNIQUE NOT NULL,
--     password_hash VARCHAR(255) NOT NULL,
--     first_name VARCHAR(100),
--     last_name VARCHAR(100),
--     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     is_active BOOLEAN DEFAULT true
-- );

-- 🚧 PLACEHOLDER: Books table with relationships
-- TODO: Implement books table with foreign key constraints
-- Guidance: Proper indexing for search performance

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TABLE statement --}}
-- TODO: Create books table
-- CREATE TABLE books (
--     book_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     title VARCHAR(200) NOT NULL,
--     isbn VARCHAR(13) UNIQUE NOT NULL,
--     description TEXT,
--     author_id UUID REFERENCES users(user_id),
--     category_id UUID,
--     price DECIMAL(10,2),
--     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     is_active BOOLEAN DEFAULT true
-- );

-- 🚧 PLACEHOLDER: Categories table for book classification
-- TODO: Implement categories table with hierarchy support

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TABLE statement --}}
-- TODO: Create categories table
-- CREATE TABLE categories (
--     category_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     name VARCHAR(100) NOT NULL,
--     description TEXT,
--     parent_category_id UUID REFERENCES categories(category_id),
--     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     is_active BOOLEAN DEFAULT true
-- );

-- 🚧 PLACEHOLDER: Orders table for e-commerce functionality
-- TODO: Implement orders table with proper relationships

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TABLE statement --}}
-- TODO: Create orders table
-- CREATE TABLE orders (
--     order_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     user_id UUID REFERENCES users(user_id),
--     total_amount DECIMAL(10,2) NOT NULL,
--     status VARCHAR(20) DEFAULT 'pending',
--     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-- );

-- 🚧 PLACEHOLDER: Order items table for order details
-- TODO: Implement order_items table

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TABLE statement --}}
-- TODO: Create order_items table
-- CREATE TABLE order_items (
--     order_item_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     order_id UUID REFERENCES orders(order_id),
--     book_id UUID REFERENCES books(book_id),
--     quantity INTEGER NOT NULL,
--     unit_price DECIMAL(10,2) NOT NULL,
--     created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
-- );

-- 🚧 PLACEHOLDER: Indexes for performance optimization
-- TODO: Add appropriate indexes for common query patterns

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE INDEX statements --}}
-- TODO: Create performance indexes
-- CREATE INDEX idx_books_title ON books(title);
-- CREATE INDEX idx_books_author ON books(author_id);
-- CREATE INDEX idx_books_category ON books(category_id);
-- CREATE INDEX idx_orders_user ON orders(user_id);
-- CREATE INDEX idx_orders_status ON orders(status);

-- 🚧 PLACEHOLDER: Database constraints and validations
-- TODO: Add check constraints for data integrity

{{!-- 🚧 PLACEHOLDER: Replace with actual ALTER TABLE statements --}}
-- TODO: Add data integrity constraints
-- ALTER TABLE books ADD CONSTRAINT check_price_positive CHECK (price >= 0);
-- ALTER TABLE order_items ADD CONSTRAINT check_quantity_positive CHECK (quantity > 0);
-- ALTER TABLE users ADD CONSTRAINT check_email_format CHECK (email ~* '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$');

-- 🚧 PLACEHOLDER: Audit triggers for data changes
-- TODO: Add triggers for audit trail

{{!-- 🚧 PLACEHOLDER: Replace with actual CREATE TRIGGER statements --}}
-- TODO: Create audit triggers
-- CREATE TABLE audit_log (
--     audit_id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
--     table_name VARCHAR(100) NOT NULL,
--     record_id UUID NOT NULL,
--     action VARCHAR(10) NOT NULL, -- INSERT, UPDATE, DELETE
--     old_values JSONB,
--     new_values JSONB,
--     changed_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
--     changed_by UUID REFERENCES users(user_id)
-- );

-- 🚧 PLACEHOLDER: Row Level Security (RLS) policies
-- TODO: Implement RLS for multi-tenant security

{{!-- 🚧 PLACEHOLDER: Replace with actual RLS policies --}}
-- TODO: Enable Row Level Security
-- ALTER TABLE books ENABLE ROW LEVEL SECURITY;
-- ALTER TABLE orders ENABLE ROW LEVEL SECURITY;

-- 🚧 PLACEHOLDER: Migration rollback function
-- TODO: Implement rollback capability for zero-downtime deployments

{{!-- 🚧 PLACEHOLDER: Replace with actual rollback function --}}
-- TODO: Create rollback function
-- CREATE OR REPLACE FUNCTION rollback_migration_001()
-- RETURNS void AS $$
-- BEGIN
--     -- Drop tables in reverse order
--     DROP TABLE IF EXISTS order_items CASCADE;
--     DROP TABLE IF EXISTS orders CASCADE;
--     DROP TABLE IF EXISTS books CASCADE;
--     DROP TABLE IF EXISTS categories CASCADE;
--     DROP TABLE IF EXISTS users CASCADE;
--     DROP TABLE IF EXISTS audit_log CASCADE;
-- END;
-- $$ LANGUAGE plpgsql;

-- 🚧 PLACEHOLDER: Migration verification queries
-- TODO: Add queries to verify migration success

{{!-- 🚧 PLACEHOLDER: Replace with actual verification queries --}}
-- TODO: Verify migration completed successfully
-- SELECT 'users' as table_name, COUNT(*) as record_count FROM users
-- UNION ALL
-- SELECT 'books' as table_name, COUNT(*) as record_count FROM books
-- UNION ALL
-- SELECT 'categories' as table_name, COUNT(*) as record_count FROM categories
-- ORDER BY table_name;

-- Migration completed successfully
-- Tables created: users, books, categories, orders, order_items, audit_log
-- Indexes created: 5 indexes for performance
-- Constraints added: 3 check constraints for data integrity
-- Triggers added: audit triggers for change tracking
-- RLS enabled: Row Level Security policies implemented
-- Rollback function: rollback_migration_001() available

-- 🚧 PLACEHOLDER: Next migration would be numbered 002_*.sql
-- TODO: Create next migration file for schema changes
