---
title: rolling() | Tiger Data Docs
description: Combine multiple one-dimensional statistical aggregates to calculate rolling window aggregates
---

Since [1.3.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.3.0)

Combine multiple intermediate statistical aggregate (`StatsSummary1D`) objects into a single `StatsSummary1D` object. It is optimized for use in a window function context for computing tumbling window statistical aggregates.

This is especially useful for computing tumbling window aggregates from a continuous aggregate. It can be orders of magnitude faster because it uses inverse transition and combine functions, with the possibility that bigger floating point errors can occur in unusual scenarios.

For re-aggregation in a non-window function context, such as combining hourly buckets into daily buckets, see `rollup()`.

## Samples

Combine hourly continuous aggregates to create a tumbling window daily aggregate. Calculate the average and standard deviation using the appropriate accessors:

```
CREATE MATERIALIZED VIEW foo_hourly
WITH (timescaledb.continuous)
AS SELECT
  time_bucket('1h'::interval, ts) AS bucket,
  stats_agg(value) as stats
FROM foo
GROUP BY 1;


SELECT
  bucket,
  average(rolling(stats) OVER (ORDER BY bucket RANGE '1 day' PRECEDING)),
  stddev(rolling(stats) OVER (ORDER BY bucket RANGE '1 day' PRECEDING)),
FROM foo_hourly;
```

## Arguments

The syntax is:

```
rolling(
    ss StatsSummary1D
) RETURNS StatsSummary1D
```

| Name    | Type           | Default | Required | Description                                              |
| ------- | -------------- | ------- | -------- | -------------------------------------------------------- |
| summary | StatsSummary1D | -       | ✔        | The statistical aggregate produced by a `stats_agg` call |

## Returns

| Column  | Type           | Description                                                                        |
| ------- | -------------- | ---------------------------------------------------------------------------------- |
| rolling | StatsSummary1D | A new statistical aggregate produced by combining the input statistical aggregates |