BatchWriteItem - Amazon DynamoDB
Request SyntaxRequest ParametersResponse SyntaxResponse ElementsErrorsExamplesSee Also

BatchWriteItem

The BatchWriteItem operation puts or deletes multiple items in one or more tables. A single call to BatchWriteItem can transmit up to 16MB of data over the network, consisting of up to 25 item put or delete operations. While individual items can be up to 400 KB once stored, it's important to note that an item's representation might be greater than 400KB while being sent in DynamoDB's JSON format for the API call. For more details on this distinction, see Naming Rules and Data Types.

Note

BatchWriteItem cannot update items. If you perform a BatchWriteItem operation on an existing item, that item's values will be overwritten by the operation and it will appear like it was updated. To update items, we recommend you use the UpdateItem action.

The individual PutItem and DeleteItem operations specified in BatchWriteItem are atomic; however BatchWriteItem as a whole is not. If any requested operations fail because the table's provisioned throughput is exceeded or an internal processing failure occurs, the failed operations are returned in the UnprocessedItems response parameter. You can investigate and optionally resend the requests. Typically, you would call BatchWriteItem in a loop. Each iteration would check for unprocessed items and submit a new BatchWriteItem request with those unprocessed items until all items have been processed.

For tables and indexes with provisioned capacity, if none of the items can be processed due to insufficient provisioned throughput on all of the tables in the request, then BatchWriteItem returns a ProvisionedThroughputExceededException. For all tables and indexes, if none of the items can be processed due to other throttling scenarios (such as exceeding partition level limits), then BatchWriteItem returns a ThrottlingException.

Important

If DynamoDB returns any unprocessed items, you should retry the batch operation on those items. However, we strongly recommend that you use an exponential backoff algorithm. If you retry the batch operation immediately, the underlying read or write requests can still fail due to throttling on the individual tables. If you delay the batch operation using exponential backoff, the individual requests in the batch are much more likely to succeed.

For more information, see Batch Operations and Error Handling in the Amazon DynamoDB Developer Guide.

With BatchWriteItem, you can efficiently write or delete large amounts of data, such as from Amazon EMR, or copy data from another database into DynamoDB. In order to improve performance with these large-scale operations, BatchWriteItem does not behave in the same way as individual PutItem and DeleteItem calls would. For example, you cannot specify conditions on individual put and delete requests, and BatchWriteItem does not return deleted items in the response.

If you use a programming language that supports concurrency, you can use threads to write items in parallel. Your application must include the necessary logic to manage the threads. With languages that don't support threading, you must update or delete the specified items one at a time. In both situations, BatchWriteItem performs the specified put and delete operations in parallel, giving you the power of the thread pool approach without having to introduce complexity into your application.

Parallel processing reduces latency, but each specified put and delete request consumes the same number of write capacity units whether it is processed in parallel or not. Delete operations on nonexistent items consume one write capacity unit.

If one or more of the following is true, DynamoDB rejects the entire batch write operation:

  • One or more tables specified in the BatchWriteItem request does not exist.

  • Primary key attributes specified on an item in the request do not match those in the corresponding table's primary key schema.

  • You try to perform multiple operations on the same item in the same BatchWriteItem request. For example, you cannot put and delete the same item in the same BatchWriteItem request.

  • Your request contains at least two items with identical hash and range keys (which essentially is two put operations).

  • There are more than 25 requests in the batch.

  • Any individual item in a batch exceeds 400 KB.

  • The total request size exceeds 16 MB.

  • Any individual items with keys exceeding the key length limits. For a partition key, the limit is 2048 bytes and for a sort key, the limit is 1024 bytes.

Request Syntax

{
   "RequestItems": { 
      "string" : [ 
         { 
            "DeleteRequest": { 
               "Key": { 
                  "string" : { 
                     "B": blob,
                     "BOOL": boolean,
                     "BS": [ blob ],
                     "L": [ 
                        "AttributeValue"
                     ],
                     "M": { 
                        "string" : "AttributeValue"
                     },
                     "N": "string",
                     "NS": [ "string" ],
                     "NULL": boolean,
                     "S": "string",
                     "SS": [ "string" ]
                  }
               }
            },
            "PutRequest": { 
               "Item": { 
                  "string" : { 
                     "B": blob,
                     "BOOL": boolean,
                     "BS": [ blob ],
                     "L": [ 
                        "AttributeValue"
                     ],
                     "M": { 
                        "string" : "AttributeValue"
                     },
                     "N": "string",
                     "NS": [ "string" ],
                     "NULL": boolean,
                     "S": "string",
                     "SS": [ "string" ]
                  }
               }
            }
         }
      ]
   },
   "ReturnConsumedCapacity": "string",
   "ReturnItemCollectionMetrics": "string"
}

Request Parameters

The request accepts the following data in JSON format.

Note

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

RequestItems

A map of one or more table names or table ARNs and, for each table, a list of operations to be performed (DeleteRequest or PutRequest). Each element in the map consists of the following:

  • DeleteRequest - Perform a DeleteItem operation on the specified item. The item to be deleted is identified by a Key subelement:

    • Key - A map of primary key attribute values that uniquely identify the item. Each entry in this map consists of an attribute name and an attribute value. For each primary key, you must provide all of the key attributes. For example, with a simple primary key, you only need to provide a value for the partition key. For a composite primary key, you must provide values for both the partition key and the sort key.

  • PutRequest - Perform a PutItem operation on the specified item. The item to be put is identified by an Item subelement:

    • Item - A map of attributes and their values. Each entry in this map consists of an attribute name and an attribute value. Attribute values must not be null; string and binary type attributes must have lengths greater than zero; and set type attributes must not be empty. Requests that contain empty values are rejected with a ValidationException exception.

      If you specify any attributes that are part of an index key, then the data types for those attributes must match those of the schema in the table's attribute definition.

Type: String to array of WriteRequest objects map

Map Entries: Maximum number of 25 items.

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

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

Required: Yes

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

ReturnItemCollectionMetrics

Determines whether item collection metrics are returned. If set to SIZE, the response includes statistics about item collections, if any, that were modified during the operation are returned in the response. If set to NONE (the default), no statistics are returned.

Type: String

Valid Values: SIZE | 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
      }
   ],
   "ItemCollectionMetrics": { 
      "string" : [ 
         { 
            "ItemCollectionKey": { 
               "string" : { 
                  "B": blob,
                  "BOOL": boolean,
                  "BS": [ blob ],
                  "L": [ 
                     "AttributeValue"
                  ],
                  "M": { 
                     "string" : "AttributeValue"
                  },
                  "N": "string",
                  "NS": [ "string" ],
                  "NULL": boolean,
                  "S": "string",
                  "SS": [ "string" ]
               }
            },
            "SizeEstimateRangeGB": [ number ]
         }
      ]
   },
   "UnprocessedItems": { 
      "string" : [ 
         { 
            "DeleteRequest": { 
               "Key": { 
                  "string" : { 
                     "B": blob,
                     "BOOL": boolean,
                     "BS": [ blob ],
                     "L": [ 
                        "AttributeValue"
                     ],
                     "M": { 
                        "string" : "AttributeValue"
                     },
                     "N": "string",
                     "NS": [ "string" ],
                     "NULL": boolean,
                     "S": "string",
                     "SS": [ "string" ]
                  }
               }
            },
            "PutRequest": { 
               "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

The capacity units consumed by the entire BatchWriteItem operation.

Each element consists of:

  • TableName - The table that consumed the provisioned throughput.

  • CapacityUnits - The total number of capacity units consumed.

Type: Array of ConsumedCapacity objects

ItemCollectionMetrics

A list of tables that were processed by BatchWriteItem and, for each table, information about any item collections that were affected by individual DeleteItem or PutItem operations.

Each entry consists of the following subelements:

  • ItemCollectionKey - The partition key value of the item collection. This is the same as the partition key value of the item.

  • SizeEstimateRangeGB - An estimate of item collection size, expressed in GB. This is a two-element array containing a lower bound and an upper bound for the estimate. The estimate includes the size of all the items in the table, plus the size of all attributes projected into all of the local secondary indexes on the table. Use this estimate to measure whether a local secondary index is approaching its size limit.

    The estimate is subject to change over time; therefore, do not rely on the precision or accuracy of the estimate.

Type: String to array of ItemCollectionMetrics objects map

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

UnprocessedItems

A map of tables and requests against those tables that were not processed. The UnprocessedItems value is in the same form as RequestItems, so you can provide this value directly to a subsequent BatchWriteItem operation. For more information, see RequestItems in the Request Parameters section.

Each UnprocessedItems entry consists of a table name or table ARN and, for that table, a list of operations to perform (DeleteRequest or PutRequest).

  • DeleteRequest - Perform a DeleteItem operation on the specified item. The item to be deleted is identified by a Key subelement:

    • Key - A map of primary key attribute values that uniquely identify the item. Each entry in this map consists of an attribute name and an attribute value.

  • PutRequest - Perform a PutItem operation on the specified item. The item to be put is identified by an Item subelement:

    • Item - A map of attributes and their values. Each entry in this map consists of an attribute name and an attribute value. Attribute values must not be null; string and binary type attributes must have lengths greater than zero; and set type attributes must not be empty. Requests that contain empty values will be rejected with a ValidationException exception.

      If you specify any attributes that are part of an index key, then the data types for those attributes must match those of the schema in the table's attribute definition.

If there are no unprocessed items remaining, the response contains an empty UnprocessedItems map.

Type: String to array of WriteRequest objects map

Map Entries: Maximum number of 25 items.

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

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

ItemCollectionSizeLimitExceededException

An item collection is too large. This exception is only returned for tables that have one or more local secondary indexes.

HTTP Status Code: 400

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 quota for your account. Please contact AWS Support to request a quota 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

Examples

Multiple Operations on One Table

This example writes several items to the Forum table. The response shows that the final put operation failed, possibly because the application exceeded the provisioned throughput on the table. The UnprocessedItems object shows the unsuccessful put request. The application can call BatchWriteItem again to address such unprocessed requests.

Sample Request

POST / HTTP/1.1
Host: dynamodb.<region>.<domain>;
Accept-Encoding: identity
Content-Length: <PayloadSizeBytes>
User-Agent: <UserAgentString>
Content-Type: application/x-amz-json-1.0
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>
X-Amz-Date: <Date>
X-Amz-Target: DynamoDB_20120810.BatchWriteItem

{
    "RequestItems": {
        "Forum": [
            {
                "PutRequest": {
                    "Item": {
                        "Name": {
                            "S": "Amazon DynamoDB"
                        },
                        "Category": {
                            "S": "Amazon Web Services"
                        }
                    }
                }
            },
            {
                "PutRequest": {
                    "Item": {
                        "Name": {
                            "S": "Amazon RDS"
                        },
                        "Category": {
                            "S": "Amazon Web Services"
                        }
                    }
                }
            },
            {
                "PutRequest": {
                    "Item": {
                        "Name": {
                            "S": "Amazon Redshift"
                        },
                        "Category": {
                            "S": "Amazon Web Services"
                        }
                    }
                }
            },
            {
                "PutRequest": {
                    "Item": {
                        "Name": {
                            "S": "Amazon ElastiCache"
                        },
                        "Category": {
                            "S": "Amazon Web Services"
                        }
                    }
                }
            }
        ]
    },
    "ReturnConsumedCapacity": "TOTAL"
}

Sample Response

HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId>
x-amz-crc32: <Checksum>
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
Date: <Date>
 {
    "UnprocessedItems": {
        "Forum": [
            {
                "PutRequest": {
                    "Item": {
                        "Name": {
                            "S": "Amazon ElastiCache"
                        },
                        "Category": {
                            "S": "Amazon Web Services"
                        }
                    }
                }
            }
        ]
    },
    "ConsumedCapacity": [
        {
            "TableName": "Forum",
            "CapacityUnits": 3
        }
    ]
}

See Also

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