# MemoryRecordLeftExpression
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The left-hand side of a memory record metadata filter expression.

## Contents
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**Important**  
This data type is a UNION, so only one of the following members can be specified when used or returned.

 ** metadataKey **   <a name="BedrockAgentCore-Type-MemoryRecordLeftExpression-metadataKey"></a>
The metadata key to filter on.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Pattern: `[a-zA-Z0-9\s._:/=+@-]*`   
Required: No

## See Also
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For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon SDK for C\+\+](https://docs.amazonaws.cn/goto/SdkForCpp/bedrock-agentcore-2024-02-28/MemoryRecordLeftExpression) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/bedrock-agentcore-2024-02-28/MemoryRecordLeftExpression) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/bedrock-agentcore-2024-02-28/MemoryRecordLeftExpression)