Exam AWS Certified Developer Associate topic 1 question 327 discussion

Controversial questions... B and C are not the options. D doesn't seem to affect the performance that much (well, ok, we query and process less data, could be). Parallel scans is a good option, but scans are not recommended on the big amount of data plus the question says "query", not "scan". Overall, I'd go with A simply because it makes the most sense. If there are any scans in that large amount of data, it should improve the performance.

Never do scan on a large table

D. Query with the ProjectionExpression parameter. The ProjectionExpression parameter allows you to specify the attributes that you need in the response, rather than returning all of the attributes in the table. This can reduce the amount of data that DynamoDB needs to read and process, which can improve performance. The other solutions are not as effective: A. Parallel scans: Parallel scans can improve performance, but they can also increase cost. B. Adding a local secondary index (LSI): LSIs can improve performance for specific queries, but they can also increase cost and complexity. C. Creating a DynamoDB Accelerator (DAX) cluster: DAX clusters can provide significant performance improvements, but they are also expensive.

Parallel Scans

I would say A. Use parallel scans

Cant be C, DynamoDB DAX has a cost: https://aws.amazon.com/dynamodb/pricing/provisioned/#.E2.80.A2_DynamoDB_Accelerator_.28DAX.29

DAX is the only feasible solution I see

Option C Creating a DynamoDB Accelerator (DAX) cluster, would be the best solution for improving the performance of DynamoDB read queries without increasing the cost. DynamoDB Accelerator (DAX) is a fully-managed, highly available, in-memory cache for DynamoDB that improves the performance of read-intensive DynamoDB workloads. DAX can be used to reduce the response times of eventually consistent read workloads by an order of magnitude, from single-digit milliseconds to microseconds.

Theanswer is B A:You should avoid using scan operation on a large database C: This would create extra costs D: This parameter helps you get certain columns only and doesn't affect performance in a significant way

B. Add a local secondary index (LSI). Adding a local secondary index (LSI) can improve the performance of DynamoDB read queries as it allows you to query the data in the table using an alternate sort key, which can be different from the primary key. By using the alternate sort key in your queries, you can reduce the number of read operations required to retrieve the data, and therefore improve the query performance without increasing the cost.

A it is.

Hint is large set of data volumes, so its parallel scan

I think it's A

Question states: "improve the performance of the DynamoDB read queries without increasing the cost" - Forget B as this can only be created at the time when the table is created - C will cost money - Leaves A or D, being the question says "stores a large volume of data" and "queries" I will lean more to D. Please see the following: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-query-scan.html https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.ProjectionExpressions.html

The answer cant be A. It says query not scan. Scan and query different things in DynamoDB. If you check their API pages, you will see Scan has parallel scan option. But in Query API page, there is no such parallel scan option. Because it is not valid for Query. In this case, the answer is D.

Given: "large volume of data" in an Amazon DynamoDB table. Taking advantage of parallel scans: 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.

C. Applications that are read-intensive, but are also cost-sensitive. With DynamoDB, you provision the number of reads per second that your application requires. If read activity increases, you can increase your tables' provisioned read throughput (at an additional cost). Or, you can offload the activity from your application to a DAX cluster, and reduce the number of read capacity units that you need to purchase otherwise. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.html