Gets data records from a Kinesis data 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,
get_records returns an empty list. 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 Amazon Kinesis Data Streams Limits
in the Amazon Kinesis Data Streams Developer Guide). Your application
should have one thread per shard, each reading continuously from its
stream. To read from a stream continually, call
get_records in a loop. Use
get_shard_iterator to get the shard
iterator to specify in the first get_records
call. get_records returns a new shard iterator
in NextShardIterator. Specify the shard iterator returned in
NextShardIterator in subsequent calls to
get_records. If the shard has been closed, the
shard iterator can't return more data and
get_records 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 MiB in size, and each shard can read up
to 2 MiB 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
get_records can return. Consider your average
record size when determining this limit. The maximum number of records
that can be returned per call is 10,000.
The size of the data returned by get_records
varies depending on the utilization of the shard. The maximum size of
data that get_records can return is 10 MiB. 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 stream, subsequent calls
made within the next 1 second throw
ProvisionedThroughputExceededException.
get_records doesn't return any data when it
throws an exception. For this reason, we recommend that you wait 1
second between calls to get_records. 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 Data 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 time stamp, whereas a client-side time stamp 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
put_records). The time stamp has millisecond
precision. There are no guarantees about the time stamp accuracy, or
that the time stamp is always increasing. For example, records in a
shard or across a stream might have time stamps that are out of order.
This operation has a limit of five transactions per second per shard.
kinesis_get_records(ShardIterator, Limit)[required] 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.
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,
get_records throws InvalidArgumentException.
The default value is 10,000.
A list with the following syntax:
list(
Records = list(
list(
SequenceNumber = "string",
ApproximateArrivalTimestamp = as.POSIXct(
"2015-01-01"
),
Data = raw,
PartitionKey = "string",
EncryptionType = "NONE"|"KMS"
)
),
NextShardIterator = "string",
MillisBehindLatest = 123,
ChildShards = list(
list(
ShardId = "string",
ParentShards = list(
"string"
),
HashKeyRange = list(
StartingHashKey = "string",
EndingHashKey = "string"
)
)
)
)
svc$get_records( ShardIterator = "string", Limit = 123 )