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Get Shard Iterator

kinesis_get_shard_iterator R Documentation

Gets an Amazon Kinesis shard iterator

Description

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

When invoking this API, you must use either the StreamARN or the StreamName parameter, or both. It is recommended that you use the StreamARN input parameter when you invoke this API.

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 put_record, put_records, get_records, or describe_stream. 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 get_shard_iterator request to get the first shard iterator for use in your first get_records request and for subsequent reads use the shard iterator returned by the get_records request in NextShardIterator. A new shard iterator is returned by every get_records request in NextShardIterator, which you use in the ShardIterator parameter of the next get_records request.

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

If the shard is closed, get_shard_iterator returns a valid iterator for the last sequence number of the shard. A shard can be closed as a result of using split_shard or merge_shards.

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

Usage

kinesis_get_shard_iterator(StreamName, ShardId, ShardIteratorType,
  StartingSequenceNumber, Timestamp, StreamARN)

Arguments

StreamName

The name of the Amazon Kinesis data stream.

ShardId

[required] The shard ID of the Kinesis Data Streams shard to get the iterator for.

ShardIteratorType

[required] Determines how the shard iterator is used to start reading data records from the shard.

The following are the valid Amazon Kinesis shard iterator types:

  • AT_SEQUENCE_NUMBER - Start reading from the position denoted by a specific sequence number, provided in the value StartingSequenceNumber.

  • AFTER_SEQUENCE_NUMBER - Start reading right after the position denoted by a specific sequence number, provided in the value StartingSequenceNumber.

  • AT_TIMESTAMP - Start reading from the position denoted by a specific time stamp, provided in the value Timestamp.

  • TRIM_HORIZON - Start reading at the last untrimmed record in the shard in the system, which is the oldest data record in the shard.

  • LATEST - Start reading just after the most recent record in the shard, so that you always read the most recent data in the shard.

StartingSequenceNumber

The sequence number of the data record in the shard from which to start reading. Used with shard iterator type AT_SEQUENCE_NUMBER and AFTER_SEQUENCE_NUMBER.

Timestamp

The time stamp of the data record from which to start reading. Used with shard iterator type AT_TIMESTAMP. A time stamp is the Unix epoch date with precision in milliseconds. For example, ⁠2016-04-04T19:58:46.480-00:00⁠ or 1459799926.480. If a record with this exact time stamp does not exist, the iterator returned is for the next (later) record. If the time stamp is older than the current trim horizon, the iterator returned is for the oldest untrimmed data record (TRIM_HORIZON).

StreamARN

The ARN of the stream.

Value

A list with the following syntax: 

list(
  ShardIterator = "string"
)

Request syntax

svc$get_shard_iterator(
  StreamName = "string",
  ShardId = "string",
  ShardIteratorType = "AT_SEQUENCE_NUMBER"|"AFTER_SEQUENCE_NUMBER"|"TRIM_HORIZON"|"LATEST"|"AT_TIMESTAMP",
  StartingSequenceNumber = "string",
  Timestamp = as.POSIXct(
    "2015-01-01"
  ),
  StreamARN = "string"
)