The batch_write_item operation puts or
deletes multiple items in one or more tables. A single call to
batch_write_item can write up to 16 MB of
data, which can comprise as many as 25 put or delete requests.
Individual items to be written can be as large as 400 KB.
batch_write_item cannot update items. To
update items, use the update_item action.
The individual put_item and
delete_item operations specified in
batch_write_item are atomic; however
batch_write_item 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 batch_write_item in a loop.
Each iteration would check for unprocessed items and submit a new
batch_write_item request with those
unprocessed items until all items have been processed.
If none of the items can be processed due to insufficient provisioned
throughput on all of the tables in the request, then
batch_write_item returns a
ProvisionedThroughputExceededException.
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 batch_write_item, 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,
batch_write_item does not behave in the
same way as individual put_item and
delete_item calls would. For example, you
cannot specify conditions on individual put and delete requests, and
batch_write_item 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, batch_write_item
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
batch_write_item 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
batch_write_item request. For
example, you cannot put and delete the same item in the same
batch_write_item 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.
dynamodb_batch_write_item(RequestItems, ReturnConsumedCapacity,
ReturnItemCollectionMetrics)A list with the following syntax:
list(
UnprocessedItems = list(
list(
list(
PutRequest = list(
Item = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
)
),
DeleteRequest = list(
Key = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
)
)
)
)
),
ItemCollectionMetrics = list(
list(
list(
ItemCollectionKey = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
),
SizeEstimateRangeGB = list(
123.0
)
)
)
),
ConsumedCapacity = list(
list(
TableName = "string",
CapacityUnits = 123.0,
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
Table = list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
),
LocalSecondaryIndexes = list(
list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
)
),
GlobalSecondaryIndexes = list(
list(
ReadCapacityUnits = 123.0,
WriteCapacityUnits = 123.0,
CapacityUnits = 123.0
)
)
)
)
)
[required] A map of one or more table names 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 delete_item
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 put_item 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.
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.
svc$batch_write_item(
RequestItems = list(
list(
list(
PutRequest = list(
Item = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
)
),
DeleteRequest = list(
Key = list(
list(
S = "string",
N = "string",
B = raw,
SS = list(
"string"
),
NS = list(
"string"
),
BS = list(
raw
),
M = list(
list()
),
L = list(
list()
),
NULL = TRUE|FALSE,
BOOL = TRUE|FALSE
)
)
)
)
)
),
ReturnConsumedCapacity = "INDEXES"|"TOTAL"|"NONE",
ReturnItemCollectionMetrics = "SIZE"|"NONE"
)
if (FALSE) {
# This example adds three new items to the Music table using a batch of
# three PutItem requests.
svc$batch_write_item(
RequestItems = list(
Music = list(
list(
PutRequest = list(
Item = list(
AlbumTitle = list(
S = "Somewhat Famous"
),
Artist = list(
S = "No One You Know"
),
SongTitle = list(
S = "Call Me Today"
)
)
)
),
list(
PutRequest = list(
Item = list(
AlbumTitle = list(
S = "Songs About Life"
),
Artist = list(
S = "Acme Band"
),
SongTitle = list(
S = "Happy Day"
)
)
)
),
list(
PutRequest = list(
Item = list(
AlbumTitle = list(
S = "Blue Sky Blues"
),
Artist = list(
S = "No One You Know"
),
SongTitle = list(
S = "Scared of My Shadow"
)
)
)
)
)
)
)
}
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