# HOTKEYS START

```json metadata
{
  "schema_version": 2,
  "title": "HOTKEYS START",
  "description": "Starts hotkeys tracking.",
  "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"],
  "arguments": [{"arguments":[{"display_text":"count","name":"count","type":"integer"},{"display_text":"cpu","name":"cpu","optional":true,"token":"CPU","type":"pure-token"},{"display_text":"net","name":"net","optional":true,"token":"NET","type":"pure-token"}],"name":"metrics","token":"METRICS","type":"block"},{"display_text":"k","name":"k","optional":true,"token":"COUNT","type":"integer"},{"display_text":"seconds","name":"seconds","optional":true,"token":"DURATION","type":"integer"},{"display_text":"ratio","name":"ratio","optional":true,"token":"SAMPLE","type":"integer"},{"arguments":[{"display_text":"count","name":"count","type":"integer"},{"display_text":"slot","multiple":true,"name":"slot","type":"integer"}],"name":"slots","optional":true,"token":"SLOTS","type":"block"}],
  "syntax_fmt": "HOTKEYS START METRICS count [CPU] [NET] [COUNT k] [DURATION seconds] [SAMPLE ratio] [SLOTS count slot [slot ...]]",
  "complexity": "O(1)",
  "group": "server",
  "command_flags": ["admin","noscript"],
  "acl_categories": ["@admin","@slow","@dangerous"],
  "since": "8.6.0",
  "arity": -2,
  "tableOfContents": {"sections":[{"id":"required-arguments","title":"Required arguments"},{"id":"optional-arguments","title":"Optional arguments"},{"id":"redis-software-and-redis-cloud-compatibility","title":"Redis Software and Redis Cloud compatibility"},{"id":"return-information","title":"Return information"}]}

,
  "codeExamples": []
}
```

Starts hotkeys tracking with specified metrics.

This command initiates a hotkey tracking session. You must specify which metrics to track using the required `METRICS` parameter.
An error is returned if a tracking session is already in progress.

The tracking session continues until manually stopped with [`HOTKEYS STOP`](https://redis.io/docs/latest/commands/hotkeys-stop) or automatically stopped after the specified duration.

## Required arguments

<details open><summary><code>METRICS count [CPU] [NET]</code></summary>

**Required.** Specifies which metrics to track and how many hotkeys to track.

- `count` - The number of metrics to collect (required).
- `CPU` - Track hotkeys by CPU time percentage (optional).
- `NET` - Track hotkeys by network bytes percentage (optional).

At least one of `CPU` or `NET` must be specified.

</details>

## Optional arguments

<details open><summary><code>COUNT</code></summary>

Specifies the value of K for the top-K hotkeys tracking.

</details>

<details open><summary><code>DURATION</code></summary>

The duration in seconds for how long the hotkeys tracking should run. After this time period, tracking will automatically stop. If not specified, tracking continues until manually stopped with `HOTKEYS STOP`.

</details>

<details open><summary><code>SAMPLE</code></summary>

Sampling ratio for probabilistic tracking. Each key is sampled with probability `1/ratio`. Higher values reduce performance impact but may miss some hotkeys. Lower values provide more accurate results but with higher performance cost.

</details>

<details open><summary><code>SLOTS</code></summary>

Specifies which hash slots to track in a cluster environment. Takes a count followed by that many slot numbers. Only keys that hash to the specified slots will be tracked. Useful for tracking hotkeys on specific shards in a Redis cluster. Using `SLOTS` when not in cluster mode will result in an error.

</details>

## Redis Software and Redis Cloud compatibility

| Redis<br />Software | Redis<br />Cloud | <span style="min-width: 9em; display: table-cell">Notes</span> |
|:----------------------|:-----------------|:------|
| <span title="Supported">&#x2705; Standard</span><br /><span title="Supported"><nobr>&#x2705; Active-Active</nobr></span> | <span title="Supported">&#x2705; Standard</span><br /><span title="Supported"><nobr>&#x2705; Active-Active</nobr></span> |  |

## Return information

**RESP2:**

One of the following:

- [Simple string](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-strings) reply: `OK` when tracking is successfully started.
- [Error reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-errors): when invalid parameters are provided.

**RESP3:**

One of the following:

- [Simple string](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-strings) reply: `OK` when tracking is successfully started.
- [Error reply](https://redis.io/docs/latest/develop/reference/protocol-spec#simple-errors): when invalid parameters are provided.