# Database Administration

Likwid uses PostgreSQL 16+ for data storage.

## Connection

```bash
# Connection string format
DATABASE_URL=postgres://user:password@host:port/database

# Example
DATABASE_URL=postgres://likwid:secret@localhost:5432/likwid_prod
```

## Migrations

Migrations are managed with SQLx.

### Running Migrations

```bash
cd backend
export DATABASE_URL="postgres://..."
sqlx migrate run
```

### Checking Status

```bash
sqlx migrate info
```

### Creating New Migrations

```bash
sqlx migrate add <migration_name>
```

## Key Tables

| Table | Purpose |
|-------|---------|
| `users` | User accounts |
| `communities` | Organizations |
| `community_members` | Membership relationships |
| `proposals` | Decision items |
| `proposal_options` | Voting options |
| `votes` | Cast votes |
| `delegations` | Delegation relationships |
| `moderation_log` | Audit trail |
| `comments` | Discussion comments |
| `topics` | Categorization for proposals |

## Backup

### Full Backup

```bash
pg_dump -h localhost -U likwid likwid_prod > backup_$(date +%Y%m%d).sql
```

### Automated Backups

Set up a cron job:
```bash
0 3 * * * pg_dump -h localhost -U likwid likwid_prod | gzip > /backups/likwid_$(date +\%Y\%m\%d).sql.gz
```

### Restore

```bash
psql -h localhost -U likwid likwid_prod < backup.sql
```

## Maintenance

### Vacuum

Run periodically to reclaim space:
```sql
VACUUM ANALYZE;
```

### Index Maintenance

```sql
REINDEX DATABASE likwid_prod;
```

### Connection Monitoring

```sql
SELECT * FROM pg_stat_activity WHERE datname = 'likwid_prod';
```

## Performance

### Key Indexes

Likwid creates indexes on:
- User lookups (username, email)
- Community slugs
- Proposal status and dates
- Vote relationships

### Query Analysis

```sql
EXPLAIN ANALYZE SELECT * FROM proposals WHERE community_id = '...';
```

## Security

### User Permissions

Create a dedicated database user:
```sql
CREATE USER likwid WITH PASSWORD 'strong_password';
GRANT ALL PRIVILEGES ON DATABASE likwid_prod TO likwid;
```

### Connection Limits

```sql
ALTER USER likwid CONNECTION LIMIT 50;
```

### SSL Connections

For production, require SSL:
```
DATABASE_URL=postgres://user:pass@host/db?sslmode=require
```