# PostgreSQL Migration Completed

## Changes Made
- **Docker Compose**: Added PostgreSQL 15 service with persistent data volume
- **Database Configuration**: Migrated from SQLite3 to PostgreSQL using pg library
- **Package Dependencies**: Updated package.json (removed sqlite3, added pg and @types/pg)
- **Database Class**: Converted all methods to use PostgreSQL syntax and async/await pattern

## Key Configuration
- Database URL: `postgresql://quixotic:quixotic123@postgres:5432/quixotic`
- Container: `quixotic-postgres` with health checks
- Volume: `postgres-data` for data persistence
- Environment variables: POSTGRES_DB, POSTGRES_USER, POSTGRES_PASSWORD

## Database Schema Changes
- INTEGER PRIMARY KEY → SERIAL PRIMARY KEY
- BIGINT for telegram_id (better for large Telegram IDs)
- TIMESTAMP instead of DATETIME
- PostgreSQL-style REFERENCES syntax for foreign keys
- ON CONFLICT DO UPDATE for upsert operations

## Status
✅ Migration completed successfully
✅ Application starts without database errors
✅ All dependencies installed
✅ Docker containers running properly