databases

# Database Management Skill

**Bonded to:** `database-management-agent`

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## Quick Start

```bash
# Invoke databases skill
"Design a database schema for my e-commerce application"
"Optimize slow queries in PostgreSQL"
"Set up Redis caching for session storage"
```

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## Instructions

1. **Analyze Requirements**: Understand data patterns, volume, access needs
2. **Select Database**: Choose SQL vs NoSQL based on requirements
3. **Design Schema**: Create data models, relationships, constraints
4. **Optimize Queries**: Implement indexes, analyze execution plans
5. **Set Up Operations**: Configure backup, replication, monitoring

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## Database Selection Guide

| Type | Best For | ACID | Scale | Examples |
|------|----------|------|-------|----------|
| Relational | Complex queries, transactions | Full | Vertical | PostgreSQL, MySQL |
| Document | Flexible schema, JSON | Partial | Horizontal | MongoDB |
| Key-Value | Caching, sessions | No | Horizontal | Redis |
| Wide-Column | Time series, analytics | Partial | Horizontal | Cassandra |
| Graph | Relationships | Varies | Varies | Neo4j |
| Search | Full-text search | No | Horizontal | Elasticsearch |

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## Decision Tree

```
Need ACID transactions?
    │
    ├─→ Yes → Complex queries?
    │           ├─→ Yes → PostgreSQL
    │           └─→ No  → MySQL
    │
    └─→ No  → Data type?
              ├─→ Documents/JSON → MongoDB
              ├─→ Key-Value pairs → Redis
              ├─→ Time series → Cassandra/TimescaleDB
              └─→ Full-text search → Elasticsearch
```

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## Examples

### Example 1: Schema Design
```sql
-- E-commerce schema
CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    email VARCHAR(255) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE products (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    name VARCHAR(255) NOT NULL,
    price DECIMAL(10,2) NOT NULL CHECK (price > 0),
    stock I