The SQS message retention period is configurable and can be set anywhere from 1 minute to 2 weeks. The default is 4 days and once the message retention limit is reached your messages will be automatically deleted. The option for longer message retention provides greater flexibility to allow for longer intervals between message production and consumption.

When a user creates an EBS volume and attaches it as a device, it is required to mount the device. If the device/volume is not mounted it will not be available in the listing.

SQS supports a maximum message size of 256kb. The transport works around this size limit by using Amazon S3 to store message payloads for messages that are larger than 256kb in size

A message can be stored in the Simple Queue Service (SQS) from 1 minute up to a maximum of 14 days.

In DynamoDB, a secondary index is a data structure that contains a subset of attributes from a table, along with an alternate key to support Query operations.

When a user is trying to mount a blank EBS volume, it is required that the user first creates a file system within the volume. If the volume is created from an existing snapshot then the user needs not to create a file system on the volume as it will wipe out the existing data.

Spot instances are the cheapest option, and you can use minimum run duration if your AMI takes more than a few minutes to create. Spot instances are also available to run for a predefined duration - in hourly increments up to six hours in length - at a significant discount (30-45%) compared to On-Demand pricing plus an additional 5% during off-peak times1 for a total of up to 50% savings.

Reference:

https://aws.amazon.com/ec2/spot/pricing/

Global secondary index ג€" an index with a partition key and a sort key that can be different from those on the table. A global secondary index is considered "global" because queries on the index can span all of the data in a table, across all partitions.

Reference:

http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SecondaryIndexes.html

The message timeout defines how long after a successful receive request SQS waits before allowing jobs to be seen by other components, and proper configuration prevents duplicate processing.

Reference:

http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/MessageLife cycle.html

One benefit of long polling with Amazon SQS is the reduction of the number of empty responses, when there are no messages available to return, in reply to a

ReceiveMessage request sent to an Amazon SQS queue. Long polling allows the Amazon SQS service to wait until a message is available in the queue before sending a response.

Reference:

http://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-longpolling.html