# PostgreSQL Setup for Northern Thailand Ping River Monitor

This guide helps you configure PostgreSQL as the database backend for the water monitoring system.

## Prerequisites

- PostgreSQL server running on a remote machine (already available)
- Network connectivity to the PostgreSQL server
- Database credentials (username, password, host, port)

## Quick Setup

### 1. Configure Environment

Copy the example environment file and configure it:

```bash
cp .env.example .env
```

Edit `.env` and update the PostgreSQL configuration:

```bash
# Database Configuration
DB_TYPE=postgresql

# PostgreSQL Configuration (Remote Server)
POSTGRES_CONNECTION_STRING=postgresql://username:password@your-postgres-host:5432/water_monitoring
```

### 2. Run Setup Script

Use the interactive setup script:

```bash
# Using uv
uv run python scripts/setup_postgres.py

# Or using make
make setup-postgres
```

The script will:
- Test your database connection
- Create the database if it doesn't exist
- Initialize the required tables and indexes
- Set up sample monitoring stations

### 3. Test Connection

Test your PostgreSQL connection:

```bash
make test-postgres
```

### 4. Run the Application

Start collecting data:

```bash
# Run a test cycle
make run-test

# Start the web API
make run-api
```

## Manual Configuration

If you prefer manual setup, here's what you need:

### Connection String Format

```
postgresql://username:password@host:port/database
```

**Examples:**
- Basic: `postgresql://postgres:mypassword@192.168.1.100:5432/water_monitoring`
- With SSL: `postgresql://user:pass@host:5432/db?sslmode=require`
- With connection pooling: `postgresql://user:pass@host:5432/db?pool_size=20&max_overflow=0`

### Environment Variables

| Variable | Description | Example |
|----------|-------------|---------|
| `DB_TYPE` | Database type | `postgresql` |
| `POSTGRES_CONNECTION_STRING` | Full connection string | See above |

### Database Schema

The application uses these main tables:

1. **stations** - Monitoring station information
2. **water_measurements** - Time series water level data
3. **alert_thresholds** - Warning/danger level definitions
4. **data_quality_log** - Data collection issue tracking

See `sql/init_postgres.sql` for the complete schema.

## Connection Options

### SSL Connection

For secure connections, add SSL parameters:

```bash
POSTGRES_CONNECTION_STRING=postgresql://user:pass@host:5432/db?sslmode=require
```

SSL modes:
- `disable` - No SSL
- `require` - Require SSL
- `prefer` - Use SSL if available
- `verify-ca` - Verify certificate authority
- `verify-full` - Full certificate verification

### Connection Pooling

For high-performance applications, configure connection pooling:

```bash
POSTGRES_CONNECTION_STRING=postgresql://user:pass@host:5432/db?pool_size=20&max_overflow=0
```

Parameters:
- `pool_size` - Number of connections to maintain
- `max_overflow` - Additional connections allowed
- `pool_timeout` - Seconds to wait for connection
- `pool_recycle` - Seconds before connection refresh

## Troubleshooting

### Common Issues

**1. Connection Refused**
```
psycopg2.OperationalError: could not connect to server
```
- Check if PostgreSQL server is running
- Verify host/port in connection string
- Check firewall settings

**2. Authentication Failed**
```
psycopg2.OperationalError: FATAL: password authentication failed
```
- Verify username/password in connection string
- Check PostgreSQL pg_hba.conf configuration
- Ensure user has database access permissions

**3. Database Does Not Exist**
```
psycopg2.OperationalError: FATAL: database "water_monitoring" does not exist
```
- Run the setup script to create the database
- Or manually create: `CREATE DATABASE water_monitoring;`

**4. Permission Denied**
```
psycopg2.ProgrammingError: permission denied for table
```
- Ensure user has appropriate permissions
- Grant access: `GRANT ALL PRIVILEGES ON DATABASE water_monitoring TO username;`

### Network Configuration

For remote PostgreSQL servers, ensure:

1. **PostgreSQL allows remote connections** (`postgresql.conf`):
   ```
   listen_addresses = '*'
   port = 5432
   ```

2. **Client authentication is configured** (`pg_hba.conf`):
   ```
   # Allow connections from your application server
   host    water_monitoring    username    your.app.ip/32    md5
   ```

3. **Firewall allows PostgreSQL port**:
   ```bash
   # On PostgreSQL server
   sudo ufw allow 5432/tcp
   ```

### Performance Tuning

For optimal performance with time series data:

1. **Increase work_mem** for sorting operations
2. **Tune shared_buffers** for caching
3. **Configure maintenance_work_mem** for indexing
4. **Set up regular VACUUM and ANALYZE** for statistics

Example PostgreSQL configuration additions:
```
# postgresql.conf
shared_buffers = 256MB
work_mem = 16MB
maintenance_work_mem = 256MB
effective_cache_size = 1GB
```

## Monitoring

### Check Application Status

```bash
# View current configuration
uv run python -c "from src.config import Config; Config.print_settings()"

# Test database connection
make test-postgres

# Check latest data
psql "postgresql://user:pass@host:5432/water_monitoring" -c "SELECT COUNT(*) FROM water_measurements;"
```

### PostgreSQL Monitoring

Connect directly to check database status:

```bash
# Connect to database
psql "postgresql://username:password@host:5432/water_monitoring"

# Check table sizes
\dt+

# View latest measurements
SELECT * FROM latest_measurements LIMIT 10;

# Check data quality
SELECT issue_type, COUNT(*) FROM data_quality_log
WHERE created_at > NOW() - INTERVAL '24 hours'
GROUP BY issue_type;
```

## Backup and Maintenance

### Backup Database

```bash
# Full backup
pg_dump "postgresql://user:pass@host:5432/water_monitoring" > backup.sql

# Data only
pg_dump --data-only "postgresql://user:pass@host:5432/water_monitoring" > data_backup.sql
```

### Restore Database

```bash
# Restore full backup
psql "postgresql://user:pass@host:5432/water_monitoring" < backup.sql

# Restore data only
psql "postgresql://user:pass@host:5432/water_monitoring" < data_backup.sql
```

### Regular Maintenance

Set up regular maintenance tasks:

```sql
-- Update table statistics (run weekly)
ANALYZE;

-- Reclaim disk space (run monthly)
VACUUM;

-- Reindex tables (run quarterly)
REINDEX DATABASE water_monitoring;
```

## Next Steps

1. Set up monitoring and alerting
2. Configure data retention policies
3. Set up automated backups
4. Implement connection pooling if needed
5. Configure SSL for production use

For more advanced configuration, see the [PostgreSQL documentation](https://www.postgresql.org/docs/).