# Columnar Analytics

Nucleus includes a built-in columnar engine for analytics workloads. Run aggregations over millions of rows with vectorized execution — no ClickHouse or separate OLAP database needed.

## Inserting Data

```sql
-- Insert rows as key-value pairs
SELECT COLUMNAR_INSERT('events', 'user_id', '42', 'action', 'click', 'duration', '1.5');
SELECT COLUMNAR_INSERT('events', 'user_id', '43', 'action', 'view', 'duration', '3.2');
SELECT COLUMNAR_INSERT('events', 'user_id', '42', 'action', 'purchase', 'duration', '12.0');
```

## Aggregations

```sql
-- Count rows
SELECT COLUMNAR_COUNT('events');
-- → 3

-- Sum a column
SELECT COLUMNAR_SUM('events', 'duration');
-- → 16.7

-- Average
SELECT COLUMNAR_AVG('events', 'duration');
-- → 5.57

-- Min / Max
SELECT COLUMNAR_MIN('events', 'duration');
-- → 1.5
SELECT COLUMNAR_MAX('events', 'duration');
-- → 12.0
```

## Why Columnar?

Traditional row-oriented storage reads entire rows even when you only need one column. Columnar storage reads only the columns you reference:

| Query | Row Store | Column Store |
|-------|-----------|-------------|
| `SELECT AVG(price) FROM products` | Reads all columns | Reads only `price` |
| `SELECT * FROM products WHERE id = 5` | Reads one row | Reads all columns |

**Best for:** Aggregations, analytics, reporting, dashboards.
**Not ideal for:** Point lookups, transactional updates.

## How It Works

- **Type-aligned columns** — Values stored contiguously by type (Bool, Int32, Int64, Float64, Text)
- **Vectorized execution** — Processes data in batches for CPU cache efficiency
- **Compression** — Similar values in sequence compress better than mixed rows
- **Parallel aggregation** — Multi-threaded across column batches

## Use Cases

- **Analytics dashboards** — Fast aggregations over large datasets
- **Event tracking** — Aggregate user actions, clicks, pageviews
- **Log analysis** — Count and summarize structured log entries
- **Business intelligence** — Revenue, conversion, retention metrics
- **Time-series rollups** — Pre-aggregated summaries