Get Settings API

Get Settings Request

A GetSettingsRequest requires one or more index arguments:

GetSettingsRequest request = new GetSettingsRequest().indices("index"); 

The index whose settings we should retrieve

Optional arguments

The following arguments can optionally be provided:

request.names("index.number_of_shards"); 

One or more settings that be the only settings retrieved. If unset, all settings will be retrieved

request.includeDefaults(true); 

If true, defaults will be returned for settings not explicitly set on the index

request.indicesOptions(IndicesOptions.lenientExpandOpen()); 

Setting IndicesOptions controls how unavailable indices are resolved and how wildcard expressions are expanded

Synchronous Execution

When executing a GetSettingsRequest in the following manner, the client waits for the GetSettingsResponse to be returned before continuing with code execution:

GetSettingsResponse getSettingsResponse = client.indices().getSettings(request, RequestOptions.DEFAULT);

Synchronous calls may throw an IOException in case of either failing to parse the REST response in the high-level REST client, the request times out or similar cases where there is no response coming back from the server.

In cases where the server returns a 4xx or 5xx error code, the high-level client tries to parse the response body error details instead and then throws a generic ElasticsearchException and adds the original ResponseException as a suppressed exception to it.

Asynchronous Execution

Executing a GetSettingsRequest can also be done in an asynchronous fashion so that the client can return directly. Users need to specify how the response or potential failures will be handled by passing the request and a listener to the asynchronous get-settings method:

client.indices().getSettingsAsync(request, RequestOptions.DEFAULT, listener); 

The GetSettingsRequest to execute and the ActionListener to use when the execution completes

The asynchronous method does not block and returns immediately. Once it is completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed. Failure scenarios and expected exceptions are the same as in the synchronous execution case.

A typical listener for get-settings looks like:

ActionListener<GetSettingsResponse> listener =
    new ActionListener<GetSettingsResponse>() {
        @Override
        public void onResponse(GetSettingsResponse GetSettingsResponse) {
            
        }

        @Override
        public void onFailure(Exception e) {
            
        }
    };

Called when the execution is successfully completed.

Called when the whole GetSettingsRequest fails.

Get Settings Response

The returned GetSettingsResponse allows to retrieve information about the executed operation as follows:

String numberOfShardsString = getSettingsResponse.getSetting("index", "index.number_of_shards"); 
Settings indexSettings = getSettingsResponse.getIndexToSettings().get("index"); 
Integer numberOfShards = indexSettings.getAsInt("index.number_of_shards", null); 

We can retrieve the setting value for a particular index directly from the response as a string

We can also retrieve the Settings object for a particular index for further examination

The returned Settings object provides convenience methods for non String types

If the includeDefaults flag was set to true in the GetSettingsRequest the behavior of GetSettingsResponse will differ somewhat.

String refreshInterval = getSettingsResponse.getSetting("index", "index.refresh_interval"); 
Settings indexDefaultSettings = getSettingsResponse.getIndexToDefaultSettings().get("index"); 

Individual default setting values may be retrieved directly from the GetSettingsResponse

We may retrieve a Settings object for an index that contains those settings with default values