Current File : /home/graphicd/www/vebto/vendor/ongr/elasticsearch-dsl/docs/Aggregation/Metric/Cardinality.md
# Cardinality Aggregation
> More info about cardinality aggregation is in the [official elasticsearch docs][1]
A single-value metrics aggregation that calculates an approximate count of distinct values.
## Simple example
```JSON
{
"aggregations" : {
"author_count" : {
"cardinality" : {
"field" : "author"
}
}
}
}
```
And now the query via DSL:
```php
$cardinalityAggregation = new CardinalityAggregation('author_count');
$cardinalityAggregation->setField('author');
$search = new Search();
$search->addAggregation($cardinalityAggregation);
$queryArray = $search->toArray();
```
[1]: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-metrics-cardinality-aggregation.html
Mini Shell