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Amazon Kinesis Streams Service API Reference
API Reference (API Version 2013-12-02)

GetRecords

Gets data records from an Amazon Kinesis stream's shard.

Specify a shard iterator using the ShardIterator parameter. The shard iterator specifies the position in the shard from which you want to start reading data records sequentially. If there are no records available in the portion of the shard that the iterator points to, GetRecords returns an empty list. Note that it might take multiple calls to get to a portion of the shard that contains records.

You can scale by provisioning multiple shards per stream while considering service limits (for more information, see Streams Limits in the Amazon Kinesis Streams Developer Guide). Your application should have one thread per shard, each reading continuously from its stream. To read from a stream continually, call GetRecords in a loop. Use GetShardIterator to get the shard iterator to specify in the first GetRecords call. GetRecords returns a new shard iterator in NextShardIterator. Specify the shard iterator returned in NextShardIterator in subsequent calls to GetRecords. Note that if the shard has been closed, the shard iterator can't return more data and GetRecords returns null in NextShardIterator. You can terminate the loop when the shard is closed, or when the shard iterator reaches the record with the sequence number or other attribute that marks it as the last record to process.

Each data record can be up to 1 MB in size, and each shard can read up to 2 MB per second. You can ensure that your calls don't exceed the maximum supported size or throughput by using the Limit parameter to specify the maximum number of records that GetRecords can return. Consider your average record size when determining this limit.

The size of the data returned by GetRecords varies depending on the utilization of the shard. The maximum size of data that GetRecords can return is 10 MB. If a call returns this amount of data, subsequent calls made within the next 5 seconds throw ProvisionedThroughputExceededException. If there is insufficient provisioned throughput on the shard, subsequent calls made within the next 1 second throw ProvisionedThroughputExceededException. Note that GetRecords won't return any data when it throws an exception. For this reason, we recommend that you wait one second between calls to GetRecords; however, it's possible that the application will get exceptions for longer than 1 second.

To detect whether the application is falling behind in processing, you can use the MillisBehindLatest response attribute. You can also monitor the stream using CloudWatch metrics and other mechanisms (see Monitoring in the Amazon Kinesis Streams Developer Guide).

Each Amazon Kinesis record includes a value, ApproximateArrivalTimestamp, that is set when a stream successfully receives and stores a record. This is commonly referred to as a server-side timestamp, whereas a client-side timestamp is set when a data producer creates or sends the record to a stream (a data producer is any data source putting data records into a stream, for example with PutRecords). The timestamp has millisecond precision. There are no guarantees about the timestamp accuracy, or that the timestamp is always increasing. For example, records in a shard or across a stream might have timestamps that are out of order.

Request Syntax

{
   "Limit": number,
   "ShardIterator": "string"
}

Request Parameters

The request requires the following data in JSON format.

Limit

The maximum number of records to return. Specify a value of up to 10,000. If you specify a value that is greater than 10,000, GetRecords throws InvalidArgumentException.

Type: Integer

Valid Range: Minimum value of 1. Maximum value of 10000.

Required: No

ShardIterator

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

Type: String

Length Constraints: Minimum length of 1. Maximum length of 512.

Required: Yes

Response Syntax

{
   "MillisBehindLatest": number,
   "NextShardIterator": "string",
   "Records": [ 
      { 
         "ApproximateArrivalTimestamp": number,
         "Data": blob,
         "PartitionKey": "string",
         "SequenceNumber": "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.

MillisBehindLatest

The number of milliseconds the GetRecords response is from the tip of the stream, indicating how far behind current time the consumer is. A value of zero indicates record processing is caught up, and there are no new records to process at this moment.

Type: Long

Valid Range: Minimum value of 0.

NextShardIterator

The next position in the shard from which to start sequentially reading data records. If set to null, the shard has been closed and the requested iterator will not return any more data.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 512.

Records

The data records retrieved from the shard.

Type: array of Record objects

Errors

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

ExpiredIteratorException

The provided iterator exceeds the maximum age allowed.

HTTP Status Code: 400

InvalidArgumentException

A specified parameter exceeds its restrictions, is not supported, or can't be used. For more information, see the returned message.

HTTP Status Code: 400

ProvisionedThroughputExceededException

The request rate for the stream is too high, or the requested data is too large for the available throughput. Reduce the frequency or size of your requests. For more information, see Streams Limits in the Amazon Kinesis Streams Developer Guide, and Error Retries and Exponential Backoff in AWS in the AWS General Reference.

HTTP Status Code: 400

ResourceNotFoundException

The requested resource could not be found. The stream might not be specified correctly.

HTTP Status Code: 400

Example

To get data from the shards in a stream

The following JSON example gets data from the shards in a stream.

Sample Request


POST / HTTP/1.1
Host: kinesis.<region>.<domain>
x-amz-Date: <Date>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=content-type;date;host;user-agent;x-amz-date;x-amz-target;x-amzn-requestid, Signature=<Signature>
User-Agent: <UserAgentString>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Connection: Keep-Alive X-Amz-Target: Kinesis_20131202.GetRecords
{
  "ShardIterator": "AAAAAAAAAAETYyAYzd665+8e0X7JTsASDM/Hr2rSwc0X2qz93iuA3udrjTH+ikQvpQk/1ZcMMLzRdAesqwBGPnsthzU0/CBlM/U8/8oEqGwX3pKw0XyeDNRAAZyXBo3MqkQtCpXhr942BRTjvWKhFz7OmCb2Ncfr8Tl2cBktooi6kJhr+djN5WYkB38Rr3akRgCl9qaU4dY=",
  "Limit": 25
}

Sample Response


HTTP/1.1 200 OK
x-amzn-RequestId: <RequestId>
Content-Type: application/x-amz-json-1.1
Content-Length: <PayloadSizeBytes>
Date: <Date> 
{
  "MillisBehindLatest": 2100,
  "NextShardIterator": "AAAAAAAAAAHsW8zCWf9164uy8Epue6WS3w6wmj4a4USt+CNvMd6uXQ+HL5vAJMznqqC0DLKsIjuoiTi1BpT6nW0LN2M2D56zM5H8anHm30Gbri9ua+qaGgj+3XTyvbhpERfrezgLHbPB/rIcVpykJbaSj5tmcXYRmFnqZBEyHwtZYFmh6hvWVFkIwLuMZLMrpWhG5r5hzkE=",
  "Records": [
    {
      "Data": "XzxkYXRhPl8w",
      "PartitionKey": "partitionKey",
      "ApproximateArrivalTimestamp": 1.441215410867E9,
      "SequenceNumber": "21269319989652663814458848515492872193"
    }
  ] 
}