---
navigation_title: "Date index name"
mapped_pages:
  - https://www.elastic.co/guide/en/elasticsearch/reference/current/date-index-name-processor.html
---

# Date index name processor [date-index-name-processor]


The purpose of this processor is to point documents to the right time based index based on a date or timestamp field in a document by using the [date math index name support](/reference/elasticsearch/rest-apis/api-conventions.md#api-date-math-index-names).

The processor sets the `_index` metadata field with a date math index name expression based on the provided index name prefix, a date or timestamp field in the documents being processed and the provided date rounding.

First, this processor fetches the date or timestamp from a field in the document being processed. Optionally, date formatting can be configured on how the field’s value should be parsed into a date. Then this date, the provided index name prefix and the provided date rounding get formatted into a date math index name expression. Also here optionally date formatting can be specified on how the date should be formatted into a date math index name expression.

An example pipeline that points documents to a monthly index that starts with a `my-index-` prefix based on a date in the `date1` field:

```console
PUT _ingest/pipeline/monthlyindex
{
  "description": "monthly date-time index naming",
  "processors" : [
    {
      "date_index_name" : {
        "field" : "date1",
        "index_name_prefix" : "my-index-",
        "date_rounding" : "M"
      }
    }
  ]
}
```

Using that pipeline for an index request:

```console
PUT /my-index/_doc/1?pipeline=monthlyindex
{
  "date1" : "2016-04-25T12:02:01.789Z"
}
```

```console-result
{
  "_index" : "my-index-2016-04-01",
  "_id" : "1",
  "_version" : 1,
  "result" : "created",
  "_shards" : {
    "total" : 2,
    "successful" : 1,
    "failed" : 0
  },
  "_seq_no" : 55,
  "_primary_term" : 1
}
```

The above request will not index this document into the `my-index` index, but into the `my-index-2016-04-01` index because it was rounded by month. This is because the date-index-name-processor overrides the `_index` property of the document.

To see the date-math value of the index supplied in the actual index request which resulted in the above document being indexed into `my-index-2016-04-01` we can inspect the effects of the processor using a simulate request.

```console
POST _ingest/pipeline/_simulate
{
  "pipeline" :
  {
    "description": "monthly date-time index naming",
    "processors" : [
      {
        "date_index_name" : {
          "field" : "date1",
          "index_name_prefix" : "my-index-",
          "date_rounding" : "M"
        }
      }
    ]
  },
  "docs": [
    {
      "_source": {
        "date1": "2016-04-25T12:02:01.789Z"
      }
    }
  ]
}
```

and the result:

```console-result
{
  "docs" : [
    {
      "doc" : {
        "_id" : "_id",
        "_index" : "<my-index-{2016-04-25||/M{yyyy-MM-dd|UTC}}>",
        "_version" : "-3",
        "_source" : {
          "date1" : "2016-04-25T12:02:01.789Z"
        },
        "_ingest" : {
          "timestamp" : "2016-11-08T19:43:03.850+0000"
        }
      }
    }
  ]
}
```

The above example shows that `_index` was set to `<my-index-{2016-04-25||/M{yyyy-MM-dd|UTC}}>`. Elasticsearch understands this to mean `2016-04-01` as is explained in the [date math index name documentation](/reference/elasticsearch/rest-apis/api-conventions.md#api-date-math-index-names)

$$$date-index-name-options$$$

| Name | Required | Default | Description |
| --- | --- | --- | --- |
| `field` | yes | - | The field to get the date or timestamp from. |
| `index_name_prefix` | no | - | A prefix of the index name to be prepended before the printed date. Supports [template snippets](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#template-snippets). |
| `date_rounding` | yes | - | How to round the date when formatting the date into the index name. Valid values are: `y` (year), `M` (month), `w` (week), `d` (day), `h` (hour), `m` (minute) and `s` (second). Supports [template snippets](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#template-snippets). |
| `date_formats` | no | yyyy-MM-dd'T'HH:mm:ss.SSSXX | An array of the expected date formats for parsing dates / timestamps in the document being preprocessed. Can be a java time pattern or one of the following formats: ISO8601, UNIX, UNIX_MS, or TAI64N. |
| `timezone` | no | UTC | The timezone to use when parsing the date and when date math index supports resolves expressions into concrete index names. |
| `locale` | no | ENGLISH | The locale to use when parsing the date from the document being preprocessed, relevant when parsing month names or week days. |
| `index_name_format` | no | yyyy-MM-dd | The format to be used when printing the parsed date into the index name. A valid java time pattern is expected here. Supports [template snippets](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#template-snippets). |
| `description` | no | - | Description of the processor. Useful for describing the purpose of the processor or its configuration. |
| `if` | no | - | Conditionally execute the processor. See [Conditionally run a processor](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#conditionally-run-processor). |
| `ignore_failure` | no | `false` | Ignore failures for the processor. See [Handling pipeline failures](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#handling-pipeline-failures). |
| `on_failure` | no | - | Handle failures for the processor. See [Handling pipeline failures](docs-content://manage-data/ingest/transform-enrich/ingest-pipelines.md#handling-pipeline-failures). |
| `tag` | no | - | Identifier for the processor. Useful for debugging and metrics. |