---
title: num_changes() | Tiger Data Docs
description: Get the number of times a gauge changed from a gauge aggregate
---

Early access [1.6.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.6.0)

Get the number of times the gauge changed during the period summarized by the gauge aggregate.

## Samples

Get the number of times the gauge changed over each 15-minute interval.

```
SELECT
    id,
    bucket,
    num_changes(summary)
FROM (
    SELECT
        id,
        time_bucket('15 min'::interval, ts) AS bucket,
        gauge_agg(ts, val) AS summary
    FROM foo
    GROUP BY id, time_bucket('15 min'::interval, ts)
) t
```

## Arguments

The syntax is:

```
num_changes(
    summary GaugeSummary
) RETURNS BIGINT
```

| Name      | Type           | Default | Required | Description                                                                                                           |
| --------- | -------------- | ------- | -------- | --------------------------------------------------------------------------------------------------------------------- |
| `summary` | `GaugeSummary` | -       | ✔        | A gauge summary created using [`gauge_agg`](/docs/reference/toolkit/counters-and-gauges/gauge_agg/gauge_agg/index.md) |

## Returns

| Column       | Type   | Description                           |
| ------------ | ------ | ------------------------------------- |
| num\_changes | BIGINT | The number of times the gauge changed |