# AggregationThreshold
<a name="API_AggregationThreshold"></a>

Specifies the minimum number of distinct identities that each query output group must represent.

## Contents
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 ** allowedAggregateExpressionType **   <a name="API-Type-AggregationThreshold-allowedAggregateExpressionType"></a>
Specifies whether a query can aggregate a transformed column. This applies to the arguments of both aggregate and window functions. Valid values are:  
 `COLUMNS_ONLY` – A query can aggregate only a direct column reference, such as `SUM(amount)`, or a constant. AWS Clean Rooms rejects a query that transforms a column and then aggregates it, such as `SUM(amount * 2)` or `SUM(ROUND(amount))`.  
 `ANY_EXPRESSION` – A query can aggregate any expression. This includes arithmetic, such as `SUM(price * quantity)`; a cast, such as `SUM(CAST(amount AS DECIMAL))`; a nested function call, such as `SUM(COALESCE(amount, 0))`; and a conditional, such as `SUM(CASE WHEN region = 'EU' THEN amount ELSE 0 END)`.  
Type: String  
Valid Values: `COLUMNS_ONLY | ANY_EXPRESSION`   
Required: Yes

 ** identityColumns **   <a name="API-Type-AggregationThreshold-identityColumns"></a>
The identity column, such as `user_id`, whose distinct values AWS Clean Rooms counts to enforce minimum aggregation thresholds. Currently, you can specify only one column, and its data type must be string, varchar, or char.  
Type: Array of strings  
Array Members: Fixed number of 1 item.  
Length Constraints: Minimum length of 1. Maximum length of 127.  
Pattern: `[a-z0-9_](([a-z0-9_ ]+-)*([a-z0-9_ ]+))?`   
Required: Yes

 ** minimumIdentityCount **   <a name="API-Type-AggregationThreshold-minimumIdentityCount"></a>
The minimum number of distinct identities that each query output group must represent. This threshold applies to all output columns in the table. To override this threshold for a specific column, use `outputColumnThresholds`.  
Type: Integer  
Valid Range: Minimum value of 2. Maximum value of 100000.  
Required: Yes

 ** type **   <a name="API-Type-AggregationThreshold-type"></a>
The type of aggregation that the threshold enforces. Currently, the only supported value is `COUNT_DISTINCT`, which counts the distinct values in the identity column.  
Type: String  
Valid Values: `COUNT_DISTINCT`   
Required: Yes

 ** outputColumnThresholds **   <a name="API-Type-AggregationThreshold-outputColumnThresholds"></a>
The per-column overrides of `minimumIdentityCount`. An output column without an override uses `minimumIdentityCount`.  
Type: Array of [OutputColumnThreshold](API_OutputColumnThreshold.md) objects  
Required: No

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\+\+](https://docs.aws.amazon.com/goto/SdkForCpp/cleanrooms-2022-02-17/AggregationThreshold) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/cleanrooms-2022-02-17/AggregationThreshold) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/cleanrooms-2022-02-17/AggregationThreshold)