AWS Certified Developer - Associate Questions and Answers (Dumps and Practice Questions)

Question : When using a large Scan operation in DynamoDB, what technique can be used to minimize
the impact of a scan on a table's provisioned throughput?

1. Set a smaller page size for the scan
2. Use parallel scans
3. Access Mostly Uused Products by 50000+ Subscribers
4. Prewarm the table by updating all items

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Explanation: Parallel Scan

By default, the Scan operation processes data sequentially. DynamoDB returns data to the application in 1 MB increments, and an application performs additional Scan operations to retrieve the next 1 MB of data.

The larger the table or index being scanned, the more time the Scan will take to complete. In addition, a sequential Scan might not always be able to fully utilize the provisioned read throughput capacity: Even though DynamoDB distributes a large table's data across multiple physical partitions, a Scan operation can only read one partition at a time. For this reason, the throughput of a Scan is constrained by the maximum throughput of a single partition.

To address these issues, the Scan operation can logically divide a table or secondary index into multiple segments, with multiple application workers scanning the segments in parallel. Each worker can be a thread (in programming languages that support multithreading) or an operating system process. To perform a parallel scan, each worker issues its own Scan request with the following parameters:

Segment - A segment to be scanned by a particular worker. Each worker should use a different value for Segment.

TotalSegments - The total number of segments for the parallel scan. This value must be the same as the number of workers that your application will use.
A parallel scan with a large number of workers can easily consume all of the provisioned throughput for the table or index being scanned. It is best to avoid such scans if the table or index is also incurring heavy read or write activity from other applications.
To control the amount of data returned per request, use the Limit parameter. This can help prevent situations where one worker consumes all of the provisioned throughput, at the expense of all other workers. For more information, see "Reduce Page Size
Many applications can benefit from using parallel Scan operations rather than sequential scans. For example, an application that processes a large table of historical data can perform a parallel scan much faster than a sequential one. Multiple worker threads in a background "sweeper" process could scan a table at a low priority without affecting production traffic. In each of these examples, a parallel Scan is used in such a way that it does not starve other applications of provisioned throughput resources.

Although parallel scans can be beneficial, they can place a heavy demand on provisioned throughput. With a parallel scan, your application will have multiple workers that are all running Scan operations concurrently, which can very quickly consume all of your table's provisioned read capacity. In that case, other applications that need to access the table might be throttled.

A parallel scan can be the right choice if the following conditions are met:

The table size is 20 GB or larger.

The table's provisioned read throughput is not being fully utilized.

Sequential Scan operations are too slow.

Question : Which of the following would you not expect to see in an SNS message body?

1. SignatureCertURL
2. Signature
3. Access Mostly Uused Products by 50000+ Subscribers
4. SubjectId

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Exp: The message ID is a unique identifier for the message, whereas a receipt handle is an identifier associated with the act of receiving the message. A new receipt handle is returned every time you receive a message. When deleting a message, you provide the last received receipt handle to delete the message.

In addition to creating IAM users with their own security credentials, IAM also enables you to grant temporary security credentials to any user allowing this user to access your AWS services and resources. You can manage users who have AWS accounts; these users are IAM users. You can also manage users for your system who do not have AWS accounts; these users are called federated users. Additionally, "users" can also be applications that you create to access your AWS resources.

You can use these temporary security credentials in making requests to Amazon SQS. The API libraries compute the necessary signature value using those credentials to authenticate your request. If you send requests using expired credentials Amazon SQS denies the request.

Question : Which of the following would you expect to see in the body of an SNS notification?

1. UnsubscribeURL
2. MessageBody
3. Access Mostly Uused Products by 50000+ Subscribers
4. SignatureId

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Explanation: Unsubscribe

Description

Deletes a subscription. If the subscription requires authentication for deletion, only the owner of the subscription or the topic's owner can unsubscribe, and an AWS signature is required. If the Unsubscribe call does not require authentication and the requester is not the subscription owner, a final cancellation message is delivered to the endpoint, so that the endpoint owner can easily resubscribe to the topic if the Unsubscribe request was unintended.

AWS Certified Developer - Associate Questions and Answers (Dumps and Practice Questions)

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