> Change Knowledge Base default vector store from OpenSearch Serverless to S3 Vectors for cost optimization

Author: Bob Strahan

CHANGELOG.md

@@ -55,6 +55,12 @@ SPDX-License-Identifier: MIT-0
   - removed image limits from multimodal inference steps (classification, extraction, assessment) following Amazon Bedrock API removal of image count restrictions. The system now processes all document pages without artificial truncation, with info logging to track image counts for monitoring purposes.
   - Resolves #147
 
+- **Knowledge Base Vector Store Default Changed to S3 Vectors**
+  - Changed default `KnowledgeBaseVectorStore` from `OPENSEARCH_SERVERLESS` to `S3_VECTORS` for cost-optimized deployments
+  - S3 Vectors provides 40-60% lower storage costs with sub-second latency suitable for most use cases
+  - OpenSearch Serverless remains available for applications requiring sub-millisecond query performance
+  - No action required for existing deployments - only affects new stack deployments
+
 ### Fixed
 
 - **Document Schema Builder Enum Support** - Fixed enum value handling in schema builder to properly support enumeration constraints for attribute definitions

docs/knowledge-base.md

@@ -55,8 +55,8 @@ The Knowledge Base feature supports two vector storage backends to optimize for
 
 ### Choosing Your Vector Store
 
-- **OpenSearch Serverless** (Default): Choose for applications requiring ultra-fast retrieval and real-time performance
-- **S3 Vectors**: Choose for cost optimization when query latency is acceptable
+- **S3 Vectors** (Default): Choose for cost optimization with acceptable sub-second query latency
+- **OpenSearch Serverless**: Choose for applications requiring ultra-fast retrieval and real-time performance
 
 ## Configuration
 
@@ -73,7 +73,7 @@ ShouldUseDocumentKnowledgeBase:
 
 KnowledgeBaseVectorStore:
   Type: String
-  Default: "OPENSEARCH_SERVERLESS"
+  Default: "S3_VECTORS"
   AllowedValues:
     - "OPENSEARCH_SERVERLESS"
     - "S3_VECTORS"

template.yaml

@@ -230,11 +230,11 @@ Parameters:
 
   KnowledgeBaseVectorStore:
     Type: String
-    Default: "OPENSEARCH_SERVERLESS"
+    Default: "S3_VECTORS"
     AllowedValues:
       - "OPENSEARCH_SERVERLESS"
       - "S3_VECTORS"
-    Description: Choose vector store type for Bedrock Knowledge Base. OpenSearch Serverless (default) for sub-millisecond queries, S3 Vectors for cost-effective storage with sub-second latency.
+    Description: Choose vector store type for Bedrock Knowledge Base. S3 Vectors (default) for cost-effective storage with sub-second latency, OpenSearch Serverless for sub-millisecond queries.
 
   KnowledgeBaseModelId:
     Type: String