GetShardIterator

Gets an Amazon Kinesis shard iterator. A shard iterator expires 5 minutes after it is returned to the requester.

A shard iterator specifies the shard position from which to start reading data records sequentially. The position is specified using the sequence number of a data record in a shard. A sequence number is the identifier associated with every record ingested in the stream, and is assigned when a record is put into the stream. Each stream has one or more shards.

You must specify the shard iterator type. For example, you can set the ShardIteratorType parameter to read exactly from the position denoted by a specific sequence number by using the AT_SEQUENCE_NUMBER shard iterator type. Alternatively, the parameter can read right after the sequence number by using the AFTER_SEQUENCE_NUMBER shard iterator type, using sequence numbers returned by earlier calls to PutRecord, PutRecords, GetRecords, or DescribeStream. In the request, you can specify the shard iterator type AT_TIMESTAMP to read records from an arbitrary point in time, TRIM_HORIZON to cause ShardIterator to point to the last untrimmed record in the shard in the system (the oldest data record in the shard), or LATEST so that you always read the most recent data in the shard.

When you read repeatedly from a stream, use a GetShardIterator request to get the first shard iterator for use in your first GetRecords request and for subsequent reads use the shard iterator returned by the GetRecords request in NextShardIterator. A new shard iterator is returned by every GetRecords request in NextShardIterator, which you use in the ShardIterator parameter of the next GetRecords request.

If a GetShardIterator request is made too often, you receive a ProvisionedThroughputExceededException. For more information about throughput limits, see GetRecords, and Streams Limits in the Amazon Kinesis Data Streams Developer Guide.

If the shard is closed, GetShardIterator returns a valid iterator for the last sequence number of the shard. A shard can be closed as a result of using SplitShard or MergeShards.

GetShardIterator has a limit of five transactions per second per account per open shard.

Request Syntax

{
   "ShardId": "string",
   "ShardIteratorType": "string",
   "StartingSequenceNumber": "string",
   "StreamARN": "string",
   "StreamName": "string",
   "Timestamp": number
}

Request Parameters

The request accepts the following data in JSON format.

Response Syntax

{
   "ShardIterator": "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.

Errors

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

Examples

To get a shard iterator

The following JSON example gets the specified shard iterator.

Sample Request

POST / HTTP/1.1
Host: kinesis.<region>.<domain>
Content-Length: <PayloadSizeBytes>
User-Agent: <UserAgentString>
Content-Type: application/x-amz-json-1.1
Authorization: <AuthParams>
Connection: Keep-Alive 
X-Amz-Date: <Date>
X-Amz-Target: Kinesis_20131202.GetShardIterator
{
  "StreamName": "exampleStreamName",
  "ShardId": "shardId-000000000001",
  "ShardIteratorType": "LATEST"
}

Sample Response

HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Date: <Date> 
{
  "ShardIterator": "AAAAAAAAAAETYyAYzd665+8e0X7JTsASDM/Hr2rSwc0X2qz93iuA3udrjTH+ikQvpQk/1ZcMMLzRdAesqwBGPnsthzU0/CBlM/U8/8oEqGwX3pKw0XyeDNRAAZyXBo3MqkQtCpXhr942BRTjvWKhFz7OmCb2Ncfr8Tl2cBktooi6kJhr+djN5WYkB38Rr3akRgCl9qaU4dY="  
}

See Also

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