Create or Update Alias (Preview REST API)

Applies to: 2023-07-01-Preview, 2021-04-30-Preview


2023-07-01-Preview (no changes).

2021-04-30-Preview adds the API.

In Azure AI Search, an alias is a secondary name that can be used to refer to an index for querying, indexing, and other operations.

You can use either POST or PUT on a create request. For either one, the JSON document in the request body provides the object definition.

POST https://[service name][api-version]      
  Content-Type: application/json  
  api-key: [admin key]  

For update requests, use PUT and specify the alias name on the URI.

PUT https://[service name][alias name]?api-version=[api-version]  
  Content-Type: application/json  
  api-key: [admin key]  

HTTPS is required for all service requests. In the case of PUT, if the alias doesn't exist, it's created. If it already exists, it's updated to the new definition.

Creating an alias establishes a mapping between an alias name and an index name. If the request is successful, the alias can be used for indexing, querying, and other operations.

Updating an alias allows you to map that alias to a different search index. When you update an existing alias, the entire definition is replaced with the contents of the request body. In general, the best pattern to use for updates is to retrieve the alias definition with a GET, modify it, and then update it with PUT.


An update to an alias may take up to 10 seconds to propagate through the system so you should wait at least 10 seconds before deleting the index that the alias was previously mapped to.


The maximum number of aliases that you can create varies by pricing tier. For more information, see Service limits.

URI Parameters

Parameter Description
service name Required. Set this value to the unique, user-defined name of your search service.
alias name Required on the URI if using PUT. The name must be lower case, start with a letter or number, have no slashes or dots, and be fewer than 128 characters. After you begin the name with a letter or number, the rest of the name can include any letter, number and dashes, as long as the dashes aren't consecutive.
api-version Required. The current preview version is 2023-07-01-Preview. See API versions for more versions.

Request Headers

The following table describes the required and optional request headers.

Fields Description
Content-Type Required. Set this value to application/json
api-key Optional if you're using Azure roles and a bearer token is provided on the request, otherwise a key is required. An api-key is a unique, system-generated string that authenticates the request to your search service. Create requests must include an api-key header set to your admin key (as opposed to a query key). See Connect to Azure AI Search using key authentication for details.

Request Body

The body of the request contains an alias definition, which includes the name of an alias and an array with the name of a single index.

The following JSON is a high-level representation of the main parts of the definition.

    "name" : (optional on PUT; required on POST) "The name of the alias",  
    "indexes" : (required) ["The name of the index the alias is mapped to"]

Request contains the following properties:

Property Description
name Required. The name of the alias. An alias name must only contain lowercase letters, digits or dashes, can't start or end with dashes and is limited to 128 characters.
indexes Required. The name of the index the alias is mapped to. Only a single index name can be included in the array.


For a successful create request, you should see status code "201 Created".

For a successful update request, you should see "204 No Content".


Example: An index alias

  "name" : "my-alias",  
  "indexes" : ["my-index"]

See also