SQS Flashcards
SQS was the first AWS service?
TRUE
What is the default Visibility Timeout?
30 seconds
What is the maximum Visibility TImeout?
12 hours
What is the maximum size of a SQS message?
256KB (text in any format, JSON, XML, plain text)
What are the two types of queues? How do they work?
- Standard Queues (default)
- nearly unlimited number of transactions per second
- messages are delivered at least once
- messages might be out of order
- FIFO Queues
- messages are delivered in order
- messages are delivered exactly once
- messages are available until a consumer processes and deletes it
- limited to 300 transactions per second
- support message groups that allow multiple ordered message groups within a single queue (messages within the same message group is processed one by one, in strict order relative to the message group, while messages that belongs to different message groups might be processed out of order)
How long can messages be kept in the queue?
1 minute to 14 days
What is the default retention period?
4 days
What is long polling?
Long polling doesn’t return a response until a message arrives in the queue or the timeout has been reached
What is SQS?
SQS is a distributed message queueing system. It allows you to decouple the components of an application so that they are independent.
What is short polling?
Short polling returns immediately even if there are no messages in the queue.
What API call can you use to extend the length of the visibility timeout for a specific message?
ChangeMessageVisibility
What is the minimum Visibility Timeout?
0 seconds
What is meant when one says that a message is ‘in flight’?
It has been received from an SQS queue by a consumer, but the message has not get been deleted.
What is the maximum number of ‘in flight’ messages for an SQS queue?
Approximately 120.000 for Standard Queues, 20.000 for FIFO queues.
What is the maximum long polling timeout?
20 seconds