---
isPrivate: true
title: Historical Data
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: Docs > Dashboards > Graphing FAQ > Historical Data
---

# Historical Data

## Graphing{% #graphing %}

If you stop reporting data to Datadog, after a certain period of time metrics, tags, and hosts no longer appear in the Datadog UI:

| Item                                          | Age Out  |
| --------------------------------------------- | -------- |
| Hosts                                         | 2 hours  |
| Metrics                                       | 24 hours |
| Tags in non-template variable dropdown panels | 12 hours |
| APM `env` tags                                | 60 days  |

Even though the data is not listed, you can still query the data with the [JSON editor](https://docs.datadoghq.com/dashboards/graphing_json/). A simple solution is to query for the host name or tags.

If you're planning to frequently churn hosts, add a tag to the [Agent](https://docs.datadoghq.com/agent/) in `datadog.yaml` or use the [Infrastructure list](https://docs.datadoghq.com/infrastructure/) (user tags).

Additionally, you can still manually apply tags or attributes by entering them in the value input field within template variable dropdown panels.

### Template variables{% #template-variables %}

Template variable dropdown panels have values that are populated from different sources based on the sources used by the dashboard. The age-out period for template variable values that are queried depends on the data source:

| Source            | Age Out                                                                                                  |
| ----------------- | -------------------------------------------------------------------------------------------------------- |
| Metrics           | 48 hours                                                                                                 |
| Cloud cost        | 48 hours                                                                                                 |
| All other sources | [Standard retention period for source](https://docs.datadoghq.com/data_security/data_retention_periods/) |

## Deleting{% #deleting %}

### Metrics and tags{% #metrics-and-tags %}

There is no way to delete a metric or tag immediately. The list above shows how long a metric or tag stays in the UI if it is no longer reporting.

For monitors, the metric stream is no longer considered after the age-out period.

For dashboards, the metric or tag appears in the visualization following the age-out period but is not available in the dropdown panels for graphing with the UI editor. The corresponding metric or tag remains available for graphing by using the [JSON](https://docs.datadoghq.com/dashboards/graphing_json/) method.

### Hosts{% #hosts %}

If you're running the Agent, and you've intentionally [stopped](https://docs.datadoghq.com/agent/configuration/agent-commands/#start-stop-restart-the-agent) or [removed](https://docs.datadoghq.com/agent/guide/how-do-i-uninstall-the-agent/) your host, all hosts that have not seen new data in 2 hours disappear from the UI. You can still query against them. However, they do not appear in dropdowns, the infrastructure list, or host map.