[role="xpack"]
[testenv="platinum"]
[[ml-preview-datafeed]]
=== Preview {dfeeds} API

[subs="attributes"]
++++
<titleabbrev>Preview {dfeeds}</titleabbrev>
++++

Previews a {dfeed}.

[[ml-preview-datafeed-request]]
==== {api-request-title}

`GET _ml/datafeeds/<datafeed_id>/_preview`

[[ml-preview-datafeed-prereqs]]
==== {api-prereq-title}

* If {es} {security-features} are enabled, you must have `monitor_ml`, `monitor`,
`manage_ml`, or `manage` cluster privileges to use this API. See
{stack-ov}/security-privileges.html[Security privileges].

[[ml-preview-datafeed-desc]]
==== {api-description-title}

The preview {dfeeds} API returns the first "page" of results from the `search`
that is created by using the current {dfeed} settings. This preview shows the
structure of the data that will be passed to the anomaly detection engine.

IMPORTANT: When {es} {security-features} are enabled, the {dfeed} query is
previewed using the credentials of the user calling the preview {dfeed} API.
When the {dfeed} is started it runs the query using the roles of the last user
to create or update it.  If the two sets of roles differ then the preview may
not accurately reflect what the {dfeed} will return when started. To avoid
such problems, the same user that creates/updates the {dfeed} should preview
it to ensure it is returning the expected data.

[[ml-preview-datafeed-path-parms]]
==== {api-path-parms-title}

`<datafeed_id>`::
  (Required, string) Identifier for the {dfeed}.

[[ml-preview-datafeed-example]]
==== {api-examples-title}

The following example obtains a preview of the `datafeed-farequote` {dfeed}:

[source,console]
--------------------------------------------------
GET _ml/datafeeds/datafeed-farequote/_preview
--------------------------------------------------
// TEST[skip:setup:farequote_datafeed]

The data that is returned for this example is as follows:

[source,console-result]
----
[
  {
    "time": 1454803200000,
    "airline": "JZA",
    "doc_count": 5,
    "responsetime": 990.4628295898438
  },
  {
    "time": 1454803200000,
    "airline": "JBU",
    "doc_count": 23,
    "responsetime": 877.5927124023438
  },
  {
    "time": 1454803200000,
    "airline": "KLM",
    "doc_count": 42,
    "responsetime": 1355.481201171875
  }
]
----