---
title: rollup() | Tiger Data Docs
description: Roll up multiple `tdigest`s
---

Since [1.0.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.0.0)

Combine multiple intermediate `tdigest` aggregates, produced by `tdigest`, into a single intermediate `tdigest` aggregate. For example, you can use `rollup` to combine `tdigest`s from 15-minute buckets into daily buckets.

## Arguments

The syntax is:

```
rollup(
  digest TDigest
) RETURNS TDigest
```

| Name   | Type    | Default | Required | Description               |
| ------ | ------- | ------- | -------- | ------------------------- |
| digest | TDigest | -       | ✔        | The `tdigest`s to roll up |

## Returns

| Column | Type    | Description                                               |
| ------ | ------- | --------------------------------------------------------- |
| rollup | TDigest | A new `tdigest` created by combining the input `tdigests` |