# Symmetric Aggregates

Symmetric aggregates allow Zenlytic to calculate your metrics accurately even when there's a situation where the joins make that very difficult by duplicating the values to aggregate.

We could go in-depth into how we do this, but we're obviously not the first to do this, and Looker has already written the best piece of content about this [here](https://cloud.google.com/looker/docs/best-practices/understanding-symmetric-aggregates), which we strongly recommend checking out.

## Examples

You can use `distinct` aggregates to tell Zenlytic how to distinctly calculate your metric. For example, this measure is a sum, but uniquely for each `order_id`.

```yaml
- name: total_price_order_level
  field_type: measure
  type: sum_distinct
  sql_distinct_key: ${order_id}
  sql: ${price} 
```