Network.AWS.Kinesis.GetShardIterator

Gets a shard iterator. A shard iterator expires five minutes after it is returned to the requester.

A shard iterator specifies the position in the shard from which to start reading data records sequentially. A shard iterator specifies this position using the sequence number of a data record in a shard. A sequence number is the identifier associated with every record ingested in the Amazon Kinesis stream. The sequence number is assigned when a record is put into the stream.

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, or 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. You can specify the shard iterator type TRIM_HORIZON in the request to cause ShardIterator to point to the last untrimmed record in the shard in the system, which is the oldest data record in the shard. Or you can point to just after the most recent record in the shard, by using the shard iterator type LATEST, so that you always read the most recent data in the shard.

When you repeatedly read from an Amazon Kinesis stream use a GetShardIterator request to get the first shard iterator for use in your first GetRecords request and then use the shard iterator returned by the GetRecords request in NextShardIterator for subsequent reads. 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.

If the shard is closed, the iterator can't return more data, and GetShardIterator returns null for its ShardIterator. A shard can be closed using SplitShard or MergeShards.

GetShardIterator has a limit of 5 transactions per second per account per open shard.

See: AWS API Reference for GetShardIterator.

Creating a Request

getShardIterator

Arguments

:: Text

gsiStreamName

-> Text

gsiShardId

-> ShardIteratorType

gsiShardIteratorType

-> GetShardIterator

Creates a value of GetShardIterator with the minimum fields required to make a request.

Use one of the following lenses to modify other fields as desired:

• gsiStartingSequenceNumber
• gsiStreamName
• gsiShardId
• gsiShardIteratorType

data GetShardIterator

Represents the input for GetShardIterator.

See: getShardIterator smart constructor.

Instances

Eq GetShardIterator

Data GetShardIterator

Read GetShardIterator

Show GetShardIterator

Generic GetShardIterator

ToJSON GetShardIterator

AWSRequest GetShardIterator

ToPath GetShardIterator

ToHeaders GetShardIterator

ToQuery GetShardIterator

type Rep GetShardIterator

type Rs GetShardIterator = GetShardIteratorResponse

Request Lenses

gsiStartingSequenceNumber :: Lens' GetShardIterator (Maybe Text)

The sequence number of the data record in the shard from which to start reading from.

gsiStreamName :: Lens' GetShardIterator Text

The name of the stream.

gsiShardId :: Lens' GetShardIterator Text

The shard ID of the shard to get the iterator for.

gsiShardIteratorType :: Lens' GetShardIterator ShardIteratorType

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

The following are the valid shard iterator types:

• AT_SEQUENCE_NUMBER - Start reading exactly from the position denoted by a specific sequence number.
• AFTER_SEQUENCE_NUMBER - Start reading right after the position denoted by a specific sequence number.
• 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.

Destructuring the Response

getShardIteratorResponse

Arguments

:: Int

gsirsResponseStatus

-> GetShardIteratorResponse

Creates a value of GetShardIteratorResponse with the minimum fields required to make a request.

Use one of the following lenses to modify other fields as desired:

• gsirsShardIterator
• gsirsResponseStatus

data GetShardIteratorResponse

Represents the output for GetShardIterator.

See: getShardIteratorResponse smart constructor.

Instances

Eq GetShardIteratorResponse

Data GetShardIteratorResponse

Read GetShardIteratorResponse

Show GetShardIteratorResponse

Generic GetShardIteratorResponse

type Rep GetShardIteratorResponse

Response Lenses

gsirsShardIterator :: Lens' GetShardIteratorResponse (Maybe Text)

The position in the shard from which to start reading data records sequentially. A shard iterator specifies this position using the sequence number of a data record in a shard.

gsirsResponseStatus :: Lens' GetShardIteratorResponse Int

The response status code.