Amazon Kinesis Service API Reference
API Reference (API Version 2013-12-02)


Splits a shard into two new shards in the stream, to increase the stream's capacity to ingest and transport data. SplitShard is called when there is a need to increase the overall capacity of stream because of an expected increase in the volume of data records being ingested.

You can also use SplitShard when a shard appears to be approaching its maximum utilization; for example, the producers sending data into the specific shard are suddenly sending more than previously anticipated. You can also call SplitShard to increase stream capacity, so that more Amazon Kinesis applications can simultaneously read data from the stream for real-time processing.

You must specify the shard to be split and the new hash key, which is the position in the shard where the shard gets split in two. In many cases, the new hash key might simply be the average of the beginning and ending hash key, but it can be any hash key value in the range being mapped into the shard. For more information about splitting shards, see Split a Shard in the Amazon Kinesis Developer Guide.

You can use DescribeStream to determine the shard ID and hash key values for the ShardToSplit and NewStartingHashKey parameters that are specified in the SplitShard request.

SplitShard is an asynchronous operation. Upon receiving a SplitShard request, Amazon Kinesis immediately returns a response and sets the stream status to UPDATING. After the operation is completed, Amazon Kinesis sets the stream status to ACTIVE. Read and write operations continue to work while the stream is in the UPDATING state.

You can use DescribeStream to check the status of the stream, which is returned in StreamStatus. If the stream is in the ACTIVE state, you can call SplitShard. If a stream is in CREATING or UPDATING or DELETING states, DescribeStream returns a ResourceInUseException.

If the specified stream does not exist, DescribeStream returns a ResourceNotFoundException. If you try to create more shards than are authorized for your account, you receive a LimitExceededException.

For the default shard limit for an AWS account, see Amazon Kinesis Limits. If you need to increase this limit, contact AWS Support.

If you try to operate on too many streams in parallel using CreateStream, DeleteStream, MergeShards, or SplitShard, you receive a LimitExceededException.

SplitShard has limit of 5 transactions per second per account.

Request Syntax

    "NewStartingHashKey": "string",
    "ShardToSplit": "string",
    "StreamName": "string"

Request Parameters

The request requires the following data in JSON format.


A hash key value for the starting hash key of one of the child shards created by the split. The hash key range for a given shard constitutes a set of ordered contiguous positive integers. The value for NewStartingHashKey must be in the range of hash keys being mapped into the shard. The NewStartingHashKey hash key value and all higher hash key values in hash key range are distributed to one of the child shards. All the lower hash key values in the range are distributed to the other child shard.

Type: String

Pattern: 0|([1-9]\d{0,38})

Required: Yes


The shard ID of the shard to split.

Type: String

Length constraints: Minimum length of 1. Maximum length of 128.

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

Required: Yes


The name of the stream for the shard split.

Type: String

Length constraints: Minimum length of 1. Maximum length of 128.

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

Required: Yes

Response Elements

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


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


A specified parameter exceeds its restrictions, is not supported, or can't be used. For more information, see the returned message.

HTTP Status Code: 400


The requested resource exceeds the maximum number allowed, or the number of concurrent stream requests exceeds the maximum number allowed (5).

HTTP Status Code: 400


The resource is not available for this operation. For successful operation, the resource needs to be in the ACTIVE state.

HTTP Status Code: 400


The requested resource could not be found. The stream might not be specified correctly, or it might not be in the ACTIVE state if the operation requires it.

HTTP Status Code: 400


To split a shard

The following example splits the specified shard:

Sample Request

Host: kinesis.<region>.<domain>
x-amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=content-type;date;host;user-agent;x-amz-date;x-amz-target;x-amzn-requestid, Signature=<Signature>
User-Agent: <UserAgentString>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Connection: Keep-Alive X-Amz-Target: Kinesis_20131202.SplitShard
  "StreamName": "exampleStreamName",
  "ShardToSplit": "shardId-000000000000",
  "NewStartingHashKey": "10"

Sample Response

HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Date: <Date>