What is the difference between data lake and data warehouse?

Question

Accepted Answer

**Data Lake** — raw data storage. **Data Warehouse** — processed, structured data.

**Data Lake:**
- Stores raw data.
- Schema-on-read.
- All data types.
- Low cost storage.
- For data scientists.

```
Data Lake:
- Raw JSON files
- Clickstream logs
- IoT sensor data
- Social media feeds
```

**Data Warehouse:**
- Stores processed data.
- Schema-on-write.
- Structured data only.
- Higher cost storage.
- For business analysts.

```
Data Warehouse:
- Dimensional models
- KPI dashboards
- Historical reports
```

**Key differences:**
- **Lake** — raw, flexible.
- **Warehouse** — processed, structured.
- **Lake** — schema-on-read.
- **Warehouse** — schema-on-write.

Systems Analyst: What is the difference between data lake and data warehouse?