[ aws . kinesis ]



Merges two adjacent shards in a Kinesis data stream and combines them into a single shard to reduce the stream’s capacity to ingest and transport data. Two shards are considered adjacent if the union of the hash key ranges for the two shards form a contiguous set with no gaps. For example, if you have two shards, one with a hash key range of 276…381 and the other with a hash key range of 382…454, then you could merge these two shards into a single shard that would have a hash key range of 276…454. After the merge, the single child shard receives data for all hash key values covered by the two parent shards.

MergeShards is called when there is a need to reduce the overall capacity of a stream because of excess capacity that is not being used. You must specify the shard to be merged and the adjacent shard for a stream. For more information about merging shards, see Merge Two Shards in the Amazon Kinesis Data Streams Developer Guide .

If the stream is in the ACTIVE state, you can call MergeShards . If a stream is in the CREATING , UPDATING , or DELETING state, MergeShards returns a ResourceInUseException . If the specified stream does not exist, MergeShards returns a ResourceNotFoundException .

You can use DescribeStream to check the state of the stream, which is returned in StreamStatus .

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

You use DescribeStream to determine the shard IDs that are specified in the MergeShards request.

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

MergeShards has a limit of five transactions per second per account.

See also: AWS API Documentation

See ‘aws help’ for descriptions of global parameters.


--stream-name <value>
--shard-to-merge <value>
--adjacent-shard-to-merge <value>
[--cli-input-json | --cli-input-yaml]
[--generate-cli-skeleton <value>]
[--cli-auto-prompt <value>]


--stream-name (string)

The name of the stream for the merge.

--shard-to-merge (string)

The shard ID of the shard to combine with the adjacent shard for the merge.

--adjacent-shard-to-merge (string)

The shard ID of the adjacent shard for the merge.

--cli-input-json | --cli-input-yaml (string) Reads arguments from the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, those values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally. This may not be specified along with --cli-input-yaml.

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. Similarly, if provided yaml-input it will print a sample input YAML that can be used with --cli-input-yaml. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command.

--cli-auto-prompt (boolean) Automatically prompt for CLI input parameters.

See ‘aws help’ for descriptions of global parameters.


To merge shards

The following merge-shards example merges two adjacent shards with IDs of shardId-000000000000 and shardId-000000000001 in the specified data stream and combines them into a single shard.

aws kinesis merge-shards \
    --stream-name samplestream \
    --shard-to-merge shardId-000000000000 \
    --adjacent-shard-to-merge shardId-000000000001

This command produces no output.

For more information, see Merging Two Shards in the Amazon Kinesis Data Streams Developer Guide.