# Hierarchical rollup

The Hierarchical rollup step allows you to compute aggregated data at every level of a hierarchy, specified as a series of columns from top to bottom level. The output data structure stacks the data of every level of the hierarchy, specifying for every row the label, level and parent in dedicated columns.

Aggregated rows can be computed with using either `sum`, `average`, `count`, `count distinct`, `min`, `max`, `first` or `last`.

### Step parameters

* `Hierarchal columns (from top to bottom level)`: here you must specify the list of columns that have a hierarchical link, in hierarchical order from top to bottom level.
* `(Optional) Columns to aggregate`: Here you can specify one or more columns to aggregate, with the corresponding aggregation function to be applied. You can add a column to aggregate by clicking on the button `Add aggregation`.
  * `Columns`: the columns to be aggregated (you can apply the same aggregation function to several columns at once)
  * `Function` the aggregation function to be applied (`sum`, `average`, `count`, `count distinct`, `min`, `max`, `first` or `last`).
* `(Optional) Group rollup by`: Optional, if you need to apply the rollup computation by groups of rows, you may specify here columns used to constitute groups.
* `(Optional) Label column name to be created`: Optional, if you want to give a custom name to the output labels column (`label` by default).
* `(Optional) Level column name to be created`: Optional, if you want to give a custom name to the output levels column (`level` by default).
* `(Optional) Parent column name to be created`: Optional, if you want to give a custom name to the output parents column (`parent` by default).

### Example

**Input**

<figure><img src="/files/S5nkjyQNr5f3GLEG8Psz" alt=""><figcaption><p>Aggregate - hierarchical rollup input</p></figcaption></figure>

**Configuration**

```json
{
    "hierarchy": ["continent", "country", "city"],
    "aggregations": [
        {
            "aggfunction": "sum",
            "columns": ["value", "value_bis"]
        }        
    ],
    "group_by": [],
    "label_col": "label",
    "level_col": "level",
    "parent_label_col": "parent"
}
```

**Result**

<figure><img src="/files/zRM21iCmIsCioqOn2E7S" alt=""><figcaption><p>Aggregate - hierarchical rollup output</p></figcaption></figure>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs-v3.toucantoco.com/data-management-in-datahub/datasets-in-toucan/preparing-data/overview-of-youprep-tm/aggregate/hierarchical-rollup.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.