Request Syntax Request Parameters Response Syntax Response Elements Errors See Also

SearchVectors

Performs a vector similarity search on a vector index associated with an Amazon DynamoDB table, and returns the most similar items sorted by similarity score based on the distance function configured for the index.

Score interpretation depends on the distance function:

COSINE - Returns the items with the k smallest scores. Scores range from 0 (identical) to 2 (opposite). Lower scores indicate higher similarity.
EUCLIDEAN - Returns the items with the k smallest scores. Scores represent the Euclidean distance between vectors. Lower scores indicate higher similarity.
DOT_PRODUCT - Returns the items with the k highest scores. Higher scores indicate higher similarity.

Request Syntax


{
   "ExpressionAttributeNames": { 
      "string" : "string" 
   },
   "ExpressionAttributeValues": { 
      "string" : { 
         "B": blob,
         "BOOL": boolean,
         "BS": [ blob ],
         "L": [ 
            "AttributeValue"
         ],
         "M": { 
            "string" : "AttributeValue"
         },
         "N": "string",
         "NS": [ "string" ],
         "NULL": boolean,
         "S": "string",
         "SS": [ "string" ]
      }
   },
   "IndexName": "string",
   "ProjectionExpression": "string",
   "ReturnConsumedCapacity": "string",
   "SearchConditionExpression": "string",
   "SearchVector": [ 
      { 
         "B": blob,
         "BOOL": boolean,
         "BS": [ blob ],
         "L": [ 
            "AttributeValue"
         ],
         "M": { 
            "string" : "AttributeValue"
         },
         "N": "string",
         "NS": [ "string" ],
         "NULL": boolean,
         "S": "string",
         "SS": [ "string" ]
      }
   ],
   "TableName": "string",
   "TopK": number
}

Request Parameters

The request accepts the following data in JSON format.

Note

In the following list, the required parameters are described first.

IndexName

The name of the vector index to search. The index must be in the ACTIVE state.

Type: String

Length Constraints: Minimum length of 3. Maximum length of 255.

Pattern: [a-zA-Z0-9_.-]+

Required: Yes

SearchVector

The search vector to compare against the indexed vectors. Each element is a 32-bit IEEE-754 floating point number, provided in DynamoDB list format.

The number of dimensions must match the number of dimensions configured for the vector index.

Type: Array of AttributeValue objects

Array Members: Minimum number of 1 item. Maximum number of 4096 items.

Required: Yes

TableName

The name or Amazon Resource Name (ARN) of the table containing the vector index.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 1024.

Required: Yes

TopK

The number of most similar results to return.

Type: Integer

Valid Range: Minimum value of 1.

Required: Yes

ExpressionAttributeNames

One or more substitution tokens for attribute names in an expression. Use the # character in an expression to dereference an attribute name.

Type: String to string map

Value Length Constraints: Maximum length of 65535.

Required: No

ExpressionAttributeValues

One or more values that can be substituted in an expression. Use the : character in an expression to dereference an attribute value.

Type: String to AttributeValue object map

Required: No

ProjectionExpression

A string that identifies one or more attributes to retrieve from the index. Separate attribute names with commas. If not specified, the operation returns all attributes projected into the vector index.

Only attributes projected into the vector index can be retrieved.

Type: String

Required: No

ReturnConsumedCapacity

Determines the level of detail about either provisioned or on-demand throughput consumption that is returned in the response:

INDEXES - The response includes the aggregate ConsumedCapacity for the operation, together with ConsumedCapacity for each table and secondary index that was accessed.

Note that some operations, such as GetItem and BatchGetItem, do not access any indexes at all. In these cases, specifying INDEXES will only return ConsumedCapacity information for table(s).
TOTAL - The response includes only the aggregate ConsumedCapacity for the operation.
NONE - No ConsumedCapacity details are included in the response.

Type: String

Valid Values: INDEXES | TOTAL | NONE

Required: No

SearchConditionExpression

A condition expression used to filter the vector search results. The expression can reference attributes defined in the vector index search schema, including HASH and INLINE_FILTER key elements.

Only the equality operator (=) is supported for HASH attributes. Comparison and range operators are supported for INLINE_FILTER attributes. Only top-level attributes from the search schema can be referenced.

Type: String

Required: No

Response Syntax


{
   "ConsumedCapacity": { 
      "VectorSearchRequestBytes": number,
      "VectorWriteRequestBytes": number
   },
   "SearchResults": [ 
      { 
         "Item": { 
            "string" : { 
               "B": blob,
               "BOOL": boolean,
               "BS": [ blob ],
               "L": [ 
                  "AttributeValue"
               ],
               "M": { 
                  "string" : "AttributeValue"
               },
               "N": "string",
               "NS": [ "string" ],
               "NULL": boolean,
               "S": "string",
               "SS": [ "string" ]
            }
         },
         "Score": number
      }
   ]
}

Response Elements

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

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

ConsumedCapacity

The capacity units consumed by the SearchVectors operation. Contains VectorSearchRequestBytes, which represents the vector search capacity consumed.

Type: VectorCapacity object

SearchResults

A list of items returned by the vector similarity search, sorted by similarity with the most similar item first. Each item contains the projected attributes and a similarity score.

Type: Array of SearchResultItem objects

Errors

For information about the errors that are common to all actions, see Common Error Types.

InternalServerError

An error occurred on the server side.

message: The server encountered an internal error trying to fulfill the request.

HTTP Status Code: 500

RequestLimitExceeded

Throughput exceeds the current throughput quota for your account. For detailed information about why the request was throttled and the ARN of the impacted resource, find the ThrottlingReason field in the returned exception. Contact Amazon Web Services Support to request a quota increase.

ThrottlingReasons: A list of ThrottlingReason that provide detailed diagnostic information about why the request was throttled.

HTTP Status Code: 400

ResourceNotFoundException

The operation tried to access a nonexistent table or index. The resource might not be specified correctly, or its status might not be ACTIVE.

message: The resource which is being requested does not exist.

HTTP Status Code: 400

ThrottlingException

The request was denied due to request throttling. For detailed information about why the request was throttled and the ARN of the impacted resource, find the ThrottlingReason field in the returned exception.

throttlingReasons: A list of ThrottlingReason that provide detailed diagnostic information about why the request was throttled.

HTTP Status Code: 400