API Version: 2013-03-31 This operation 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.

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

The SplitShard operation requires that you 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 the Amazon Kinesis Developer Guide.

You can use the DescribeStream operation 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, then Amazon Kinesis returns a ResourceInUseException.

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

Note: The default limit for an AWS account is 10 shards per stream. If you need to create a stream with more than 10 shards, contact AWS Support to increase the limit on your account.

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

SplitShard has limit of 5 transactions per second per account.

http://docs.aws.amazon.com/kinesis/2013-12-02/APIReference/API_SplitShard.html