Amazon DynamoDB
API Reference
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TransactGetItems

TransactGetItems is a synchronous operation that atomically retrieves multiple items from one or more tables (but not from indexes) in a single account and Region. A TransactGetItems call can contain up to 25 TransactGetItem objects, each of which contains a Get structure that specifies an item to retrieve from a table in the account and Region. A call to TransactGetItems cannot retrieve items from tables in more than one AWS account or Region. The aggregate size of the items in the transaction cannot exceed 4 MB.

DynamoDB rejects the entire TransactGetItems request if any of the following is true:

  • A conflicting operation is in the process of updating an item to be read.

  • There is insufficient provisioned capacity for the transaction to be completed.

  • There is a user error, such as an invalid data format.

  • The aggregate size of the items in the transaction cannot exceed 4 MB.

Request Syntax

{ "ReturnConsumedCapacity": "string", "TransactItems": [ { "Get": { "ExpressionAttributeNames": { "string" : "string" }, "Key": { "string" : { "B": blob, "BOOL": boolean, "BS": [ blob ], "L": [ "AttributeValue" ], "M": { "string" : "AttributeValue" }, "N": "string", "NS": [ "string" ], "NULL": boolean, "S": "string", "SS": [ "string" ] } }, "ProjectionExpression": "string", "TableName": "string" } } ] }

Request Parameters

The request accepts the following data in JSON format.

Note

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

TransactItems

An ordered array of up to 25 TransactGetItem objects, each of which contains a Get structure.

Type: Array of TransactGetItem objects

Array Members: Minimum number of 1 item. Maximum number of 25 items.

Required: Yes

ReturnConsumedCapacity

A value of TOTAL causes consumed capacity information to be returned, and a value of NONE prevents that information from being returned. No other value is valid.

Type: String

Valid Values: INDEXES | TOTAL | NONE

Required: No

Response Syntax

{ "ConsumedCapacity": [ { "CapacityUnits": number, "GlobalSecondaryIndexes": { "string" : { "CapacityUnits": number, "ReadCapacityUnits": number, "WriteCapacityUnits": number } }, "LocalSecondaryIndexes": { "string" : { "CapacityUnits": number, "ReadCapacityUnits": number, "WriteCapacityUnits": number } }, "ReadCapacityUnits": number, "Table": { "CapacityUnits": number, "ReadCapacityUnits": number, "WriteCapacityUnits": number }, "TableName": "string", "WriteCapacityUnits": number } ], "Responses": [ { "Item": { "string" : { "B": blob, "BOOL": boolean, "BS": [ blob ], "L": [ "AttributeValue" ], "M": { "string" : "AttributeValue" }, "N": "string", "NS": [ "string" ], "NULL": boolean, "S": "string", "SS": [ "string" ] } } } ] }

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

If the ReturnConsumedCapacity value was TOTAL, this is an array of ConsumedCapacity objects, one for each table addressed by TransactGetItem objects in the TransactItems parameter. These ConsumedCapacity objects report the read-capacity units consumed by the TransactGetItems call in that table.

Type: Array of ConsumedCapacity objects

Responses

An ordered array of up to 25 ItemResponse objects, each of which corresponds to the TransactGetItem object in the same position in the TransactItems array. Each ItemResponse object contains a Map of the name-value pairs that are the projected attributes of the requested item.

If a requested item could not be retrieved, the corresponding ItemResponse object is Null, or if the requested item has no projected attributes, the corresponding ItemResponse object is an empty Map.

Type: Array of ItemResponse objects

Array Members: Minimum number of 1 item. Maximum number of 25 items.

Errors

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

InternalServerError

An error occurred on the server side.

HTTP Status Code: 500

ProvisionedThroughputExceededException

Your request rate is too high. The AWS SDKs for DynamoDB automatically retry requests that receive this exception. Your request is eventually successful, unless your retry queue is too large to finish. Reduce the frequency of requests and use exponential backoff. For more information, go to Error Retries and Exponential Backoff in the Amazon DynamoDB Developer Guide.

HTTP Status Code: 400

RequestLimitExceeded

Throughput exceeds the current throughput limit for your account. Please contact AWS Support at AWS Support to request a limit increase.

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.

HTTP Status Code: 400

TransactionCanceledException

The entire transaction request was canceled.

DynamoDB cancels a TransactWriteItems request under the following circumstances:

  • A condition in one of the condition expressions is not met.

  • A table in the TransactWriteItems request is in a different account or region.

  • More than one action in the TransactWriteItems operation targets the same item.

  • There is insufficient provisioned capacity for the transaction to be completed.

  • An item size becomes too large (larger than 400 KB), or a local secondary index (LSI) becomes too large, or a similar validation error occurs because of changes made by the transaction.

  • The aggregate size of the items in the transaction exceeds 4 MBs.

  • There is a user error, such as an invalid data format.

DynamoDB cancels a TransactGetItems request under the following circumstances:

  • There is an ongoing TransactGetItems operation that conflicts with a concurrent PutItem, UpdateItem, DeleteItem or TransactWriteItems request. In this case the TransactGetItems operation fails with a TransactionCanceledException.

  • A table in the TransactGetItems request is in a different account or region.

  • There is insufficient provisioned capacity for the transaction to be completed.

  • The aggregate size of the items in the transaction exceeds 4 MBs.

  • There is a user error, such as an invalid data format.

Note

If using Java, DynamoDB lists the cancellation reasons on the CancellationReasons property. This property is not set for other languages. Transaction cancellation reasons are ordered in the order of requested items, if an item has no error it will have NONE code and Null message.

Cancellation reason codes and possible error messages:

  • No Errors:

    • Code: NONE

    • Message: null

  • Conditional Check Failed:

    • Code: ConditionalCheckFailed

    • Message: The conditional request failed.

  • Item Collection Size Limit Exceeded:

    • Code: ItemCollectionSizeLimitExceeded

    • Message: Collection size exceeded.

  • Transaction Conflict:

    • Code: TransactionConflict

    • Message: Transaction is ongoing for the item.

  • Provisioned Throughput Exceeded:

    • Code: ProvisionedThroughputExceeded

    • Messages:

      • The level of configured provisioned throughput for the table was exceeded. Consider increasing your provisioning level with the UpdateTable API.

        Note

        This Message is received when provisioned throughput is exceeded is on a provisioned DynamoDB table.

      • The level of configured provisioned throughput for one or more global secondary indexes of the table was exceeded. Consider increasing your provisioning level for the under-provisioned global secondary indexes with the UpdateTable API.

        Note

        This message is returned when provisioned throughput is exceeded is on a provisioned GSI.

  • Throttling Error:

    • Code: ThrottlingError

    • Messages:

      • Throughput exceeds the current capacity of your table or index. DynamoDB is automatically scaling your table or index so please try again shortly. If exceptions persist, check if you have a hot key: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-partition-key-design.html.

        Note

        This message is returned when writes get throttled on an On-Demand table as DynamoDB is automatically scaling the table.

      • Throughput exceeds the current capacity for one or more global secondary indexes. DynamoDB is automatically scaling your index so please try again shortly.

        Note

        This message is returned when when writes get throttled on an On-Demand GSI as DynamoDB is automatically scaling the GSI.

  • Validation Error:

    • Code: ValidationError

    • Messages:

      • One or more parameter values were invalid.

      • The update expression attempted to update the secondary index key beyond allowed size limits.

      • The update expression attempted to update the secondary index key to unsupported type.

      • An operand in the update expression has an incorrect data type.

      • Item size to update has exceeded the maximum allowed size.

      • Number overflow. Attempting to store a number with magnitude larger than supported range.

      • Type mismatch for attribute to update.

      • Nesting Levels have exceeded supported limits.

      • The document path provided in the update expression is invalid for update.

      • The provided expression refers to an attribute that does not exist in the item.

HTTP Status Code: 400

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: