# Aggregations

Hyperspace aggregations facilitate data analytics by summarizing and extracting insights in a structured manner. These aggregations work on a set of documents to generate summary statistics or analytical results. 

The results of these aggregations are stored as distinct keys in the query results objects. 

## **Metric Aggregations** 

Metric Aggregations compute and analyze numeric measures of document sets. These aggregations operate on the documents' numeric measures to produce a single numeric result for a specific metric. 

To create a metric aggregation, use the following structure:

{% code lineNumbers="true" %}

```json
{
  "aggs": {
    "agg_name": {
      "metric_type": {
        "fieldname": "numeric_field"
      }
    }
  }
}
```

{% endcode %}

Where:

* <mark style="color:purple;">**agg\_name:**</mark> Specifies the name (key) under which aggregation results are saved.
* <mark style="color:purple;">**metric\_type:**</mark> Specifies the type of aggregation. Possible values are:
  * **sum** – Returns the sum of the field of the relevant candidates.
  * **min** – Returns the minimum value of the field of the relevant candidates.
  * **max** – Returns the maximum value of the field of the relevant candidates.
  * **avg** – Returns the average of the field of the relevant candidates.
  * **count** – Returns the total number of valid field entries of the relevant candidates.
  * **cardinality** – Returns the total number of valid field values of the relevant candidates.
  * **percentiles** – Returns the percentiles of the field of the relevant candidates.
* <mark style="color:purple;">fieldname</mark> – Specifies the name of the field to be used in the aggregation.

**Example 1**

In the following example, the sum of the field "sales" is calculated and stored under a key named "total\_sales".

{% code lineNumbers="true" %}

```json
{
  "aggs": {
    "total_sales": {
      "sum": {
        "field": "sales"
      }
    }
  }
}
```

{% endcode %}

**Example 2**

In the following example, the number of unique values of the field "user\_id" are calculated and stored under a key named "unique\_users".

{% code lineNumbers="true" %}

```json
{
  "aggs": {
    "unique_users": {
      "cardinality": {
        "field": "user_id"
      }
    }
  }
}
```

{% endcode %}

## **Date Histogram Aggregations**&#x20;

Date Histogram Aggregation groups documents into time intervals, creating buckets based on date or time values. The basic syntax includes the following terms –

* "field" – Specifies the field to be aggregated.
* "interval" – Specifies the time interval for creating buckets. Common intervals include "year", "quarter", "month", "week", "day", "hour", "minute", or "second".

**Example**

In the following example, the result includes a set of buckets, each representing a specific day.

{% code lineNumbers="true" %}

```json
{
  "aggs": {
    "daily_histogram": {
      "date_histogram": {
        "field": "timestamp",
        "interval": "day"
      }
    }
  }
}
```

{% endcode %}

## **Combining Aggregations** and Candidate Filtering

Aggregations can be combined with candidate filtering to perform different aggregations on different candidates in the same query.

**Example**

{% code lineNumbers="true" %}

```json
{
  "query": {
    "aggs": {
    "avg_rating_electronics": {
      "avg": {
        "field": "rating"
      },
      "filter": {
        "term": {
          "category": "electronics"
        }          
      }
    },
    "avg_rating_high_price": {
      "avg": {
        "field": "rating"
      },
      "filter": {
        "range": {
          "price": {
            "gte": 50
          }
        }
      }
    }
  }
}
```

{% endcode %}

## **Terms Aggregation**&#x20;

Terms Aggregation is a type of bucket aggregation that groups documents based on the values of a particular field.

**Example**

In the following example, the aggregation is applied to the field "<mark style="color:purple;">unique\_products</mark>" across all documents that meet the query criteria. The aggregation results are stored in buckets according to the values of the field "<mark style="color:purple;">prod\_name</mark>".

{% code lineNumbers="true" %}

```json
{
   "query": {
            "bool": {
                "must": {
                    "term": {"product_type_name": "Dress"}
                }
            }
        },
        "aggs": {
            "unique_products": {
                "terms": {
                    "field": "prod_name"
                }
            }
    }
}
```

{% endcode %}

## **Cardinality Aggregation**&#x20;

Cardinality Aggregation estimates the number of unique field values within a collection, which is also called the count of distinct values or unique values.

**Example**

In the following example, the aggregation is applied to the field "<mark style="color:purple;">unique\_products</mark>" for all documents that meet the query criteria.  The aggregation results return the total number of all unique values of the field "<mark style="color:purple;">prod\_name</mark>".

{% code lineNumbers="true" %}

```json
{
   "query": {
       "bool": {
            "must": {
                "term": {"product_type_name": "Dress"}
            }
        }
    },
    "aggs": {
        "unique_products": {
            "cardinality": {
                "field": "prod_name"
            }
        }
    }
}
```

{% endcode %}

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