﻿---
title: Aliases
description: An alias points to one or more indices or data streams. Most Elasticsearch APIs accept an alias in place of a data stream or index name. Aliases enable...
url: https://www.elastic.co/elastic/docs-builder/docs/2689/manage-data/data-store/aliases
products:
  - Elasticsearch
applies_to:
  - Elastic Cloud Serverless: Generally available
  - Elastic Stack: Generally available
---

# Aliases
An alias points to one or more indices or data streams. Most Elasticsearch APIs accept an alias in place of a data stream or index name.
Aliases enable you to:
- Query multiple indices/data streams together with a single name
- Change which indices/data streams your application uses in real time
- [Reindex](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-reindex) data without downtime


## Alias types

There are two types of aliases:
- A **data stream alias** points to one or more data streams.
- An **index alias** points to one or more indices.

An alias cannot point to both data streams and indices. You also cannot add a data stream’s backing index to an index alias.

## Add an alias

To add an existing data stream or index to an alias, use the [aliases API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-update-aliases)'s `add` action. If the alias doesn’t exist, the request creates it.
```json

{
  "actions": [
    {
      "add": {
        "index": "logs-nginx.access-prod",
        "alias": "logs"
      }
    }
  ]
}
```

The API’s `index` and `indices` parameters support wildcards (`*`). Wildcard patterns that match both data streams and indices return an error.
```json

{
  "actions": [
    {
      "add": {
        "index": "logs-*",
        "alias": "logs"
      }
    }
  ]
}
```


## Remove an alias

To remove an alias, use the aliases API’s `remove` action.
```json

{
  "actions": [
    {
      "remove": {
        "index": "logs-nginx.access-prod",
        "alias": "logs"
      }
    }
  ]
}
```


## Multiple actions

You can use the aliases API to perform multiple actions in a single atomic operation.
For example, the `logs` alias points to a single data stream. The following request swaps the stream for the alias. During this swap, the `logs` alias has no downtime and never points to both streams at the same time.
```json

{
  "actions": [
    {
      "remove": {
        "index": "logs-nginx.access-prod",
        "alias": "logs"
      }
    },
    {
      "add": {
        "index": "logs-my_app-default",
        "alias": "logs"
      }
    }
  ]
}
```


## Multiple action results

When using multiple actions, if some succeed and some fail, a list of per-action results will be returned.
Consider a similar action list to the previous example, but now with an alias `log-non-existing`, which does not yet exist. In this case, the `remove` action will fail, but the `add` action will succeed. The response will contain the list `action_results`, with a result for every requested action.
```json

{
  "actions": [
    {
      "remove": {
        "index": "index1",
        "alias": "logs-non-existing"
      }
    },
    {
      "add": {
        "index": "index2",
        "alias": "logs-non-existing"
      }
    }
  ]
}
```

The API returns the following result:
```json
{
  "acknowledged": true,
  "errors": true,
  "action_results": [
    {
      "action": {
        "type": "remove",
        "indices": [ "index1" ],
        "aliases": [ "logs-non-existing" ],
      },
      "status": 404,
      "error": {
        "type": "aliases_not_found_exception",
        "reason": "aliases [logs-non-existing] missing",
        "resource.type": "aliases",
        "resource.id": "logs-non-existing"
      }
    },
    {
      "action": {
        "type": "add",
        "indices": [ "index2" ],
        "aliases": [ "logs-non-existing" ],
      },
      "status": 200
    }
  ]
}
```

Allowing the action list to succeed partially may not provide the desired result. It may be more appropriate to set `must_exist` to `true`, which will cause the entire action list to fail if a single action fails.

## Add an alias at index creation

You can also use a [component](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-cluster-put-component-template) or [index template](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-put-index-template) to add index or data stream aliases when they are created.
```json
# Component template with index aliases

{
  "template": {
    "aliases": {
      "my-alias": {}
    }
  }
}

# Index template with index aliases

{
  "index_patterns": [
    "my-index-*"
  ],
  "composed_of": [
    "my-aliases",
    "my-mappings",
    "my-settings"
  ],
  "template": {
    "aliases": {
      "yet-another-alias": {}
    }
  }
}
```

You can also specify index aliases in [create index API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-create) requests.
```json
# PUT <my-index-{now/d}-000001>

{
  "aliases": {
    "my-alias": {}
  }
}
```


## View aliases

To get a list of your cluster’s aliases, use the [get alias API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-get-alias) with no argument.
```json
```

Specify a data stream or index before `_alias` to view its aliases.
```json
```

Specify an alias after `_alias` to view its data streams or indices.
```json
```


## Write index

You can use `is_write_index` to specify a write index or data stream for an alias. Elasticsearch routes any write requests for the alias to this index or data stream.
```json

{
  "actions": [
    {
      "add": {
        "index": "logs-nginx.access-prod",
        "alias": "logs"
      }
    },
    {
      "add": {
        "index": "logs-my_app-default",
        "alias": "logs",
        "is_write_index": true
      }
    }
  ]
}
```

If an alias points to multiple indices or data streams and `is_write_index` isn’t set, the alias rejects write requests. If an index alias points to one index and `is_write_index` isn’t set, the index automatically acts as the write index. Data stream aliases don’t automatically set a write data stream, even if the alias points to one data stream.
<tip>
  We recommend using data streams to store append-only time series data. If you need to update or delete existing time series data, you can perform update or delete operations directly on the data stream backing index. If you frequently send multiple documents using the same `_id` expecting last-write-wins, you may want to use an index alias with a write index instead. See the tutorial [Manage time series data without data streams](https://www.elastic.co/elastic/docs-builder/docs/2689/manage-data/lifecycle/index-lifecycle-management/tutorial-time-series-without-data-streams).
</tip>


## Filter an alias

The `filter` option uses [Query DSL](https://www.elastic.co/elastic/docs-builder/docs/2689/explore-analyze/query-filter/languages/querydsl) to limit the documents an alias can access.
```json

{
  "actions": [
    {
      "add": {
        "index": "my-index-2099.05.06-000001",
        "alias": "my-alias",
        "filter": {
          "bool": {
            "filter": [
              {
                "range": {
                  "@timestamp": {
                    "gte": "now-1d/d",
                    "lt": "now/d"
                  }
                }
              },
              {
                "term": {
                  "user.id": "kimchy"
                }
              }
            ]
          }
        }
      }
    }
  ]
}
```

<note>
  Filters are only applied when using the [Query DSL](https://www.elastic.co/elastic/docs-builder/docs/2689/explore-analyze/query-filter/languages/querydsl), and are not applied when [retrieving a document by ID](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-get).
</note>


## Routing

Use the `routing` option to [route](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/2689/reference/elasticsearch/mapping-reference/mapping-routing-field) requests for an alias to a specific shard. This lets you take advantage of [shard caches](https://www.elastic.co/elastic/docs-builder/docs/2689/deploy-manage/distributed-architecture/shard-request-cache) to speed up searches. Data stream aliases do not support routing options.
```json

{
  "actions": [
    {
      "add": {
        "index": "my-index-2099.05.06-000001",
        "alias": "my-alias",
        "routing": "1"
      }
    }
  ]
}
```

Use `index_routing` and `search_routing` to specify different routing values for indexing and search. If specified, these options overwrite the `routing` value for their respective operations.
```json

{
  "actions": [
    {
      "add": {
        "index": "my-index-2099.05.06-000001",
        "alias": "my-alias",
        "search_routing": "1",
        "index_routing": "2"
      }
    }
  ]
}
```


## Remove an index

To remove an index, use the aliases API’s `remove_index` action.
```json

{
  "actions": [
    {
      "remove_index": {
        "index": "my-index-2099.05.06-000001"
      }
    }
  ]
}
```