# GetCardinality
<a name="API_GetCardinality"></a>

Returns the approximate count of unique values that match the query.

Requires permission to access the [GetCardinality](https://docs.aws.amazon.com/service-authorization/latest/reference/list_awsiot.html#awsiot-actions-as-permissions) action.

## Request Syntax
<a name="API_GetCardinality_RequestSyntax"></a>

```
POST /indices/cardinality HTTP/1.1
Content-type: application/json

{
   "aggregationField": "string",
   "indexName": "string",
   "queryString": "string",
   "queryVersion": "string"
}
```

## URI Request Parameters
<a name="API_GetCardinality_RequestParameters"></a>

The request does not use any URI parameters.

## Request Body
<a name="API_GetCardinality_RequestBody"></a>

The request accepts the following data in JSON format.

 ** [aggregationField](#API_GetCardinality_RequestSyntax) **   <a name="iot-GetCardinality-request-aggregationField"></a>
The field to aggregate.  
Type: String  
Length Constraints: Minimum length of 1.  
Required: No

 ** [indexName](#API_GetCardinality_RequestSyntax) **   <a name="iot-GetCardinality-request-indexName"></a>
The name of the index to search.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Pattern: `[a-zA-Z0-9:_-]+`   
Required: No

 ** [queryString](#API_GetCardinality_RequestSyntax) **   <a name="iot-GetCardinality-request-queryString"></a>
The search query string.  
Type: String  
Length Constraints: Minimum length of 1.  
Required: Yes

 ** [queryVersion](#API_GetCardinality_RequestSyntax) **   <a name="iot-GetCardinality-request-queryVersion"></a>
The query version.  
Type: String  
Required: No

## Response Syntax
<a name="API_GetCardinality_ResponseSyntax"></a>

```
HTTP/1.1 200
Content-type: application/json

{
   "cardinality": number
}
```

## Response Elements
<a name="API_GetCardinality_ResponseElements"></a>

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [cardinality](#API_GetCardinality_ResponseSyntax) **   <a name="iot-GetCardinality-response-cardinality"></a>
The approximate count of unique values that match the query.  
Type: Integer

## Errors
<a name="API_GetCardinality_Errors"></a>

 ** IndexNotReadyException **   
The index is not ready.    
 ** message **   
The message for the exception.
HTTP Status Code: 400

 ** InternalFailureException **   
An unexpected error has occurred.    
 ** message **   
The message for the exception.
HTTP Status Code: 500

 ** InvalidAggregationException **   
The aggregation is invalid.  
HTTP Status Code: 400

 ** InvalidQueryException **   
The query is invalid.    
 ** message **   
The message for the exception.
HTTP Status Code: 400

 ** InvalidRequestException **   
The request is not valid.    
 ** message **   
The message for the exception.
HTTP Status Code: 400

 ** ResourceNotFoundException **   
The specified resource does not exist.    
 ** message **   
The message for the exception.
HTTP Status Code: 404

 ** ServiceUnavailableException **   
The service is temporarily unavailable.    
 ** message **   
The message for the exception.
HTTP Status Code: 503

 ** ThrottlingException **   
The rate exceeds the limit.    
 ** message **   
The message for the exception.
HTTP Status Code: 400

 ** UnauthorizedException **   
You are not authorized to perform this operation.    
 ** message **   
The message for the exception.
HTTP Status Code: 401

## See Also
<a name="API_GetCardinality_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/iot-2015-05-28/GetCardinality) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/iot-2015-05-28/GetCardinality)