Querying Consumed Capacity in DynamoDB - Monitoring and Optimization Tips

DynamoDB Consumed Capacity Monitoring

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Question

You are developing an application that is working with a DynamoDB table.

During the development phase, you want to know how much of the Consumed capacity is being used for the queries being fired.

How can this be achieved?

Answers

Explanations

Click on the arrows to vote for the correct answer

A. B. C. D.

Answer - C.

The AWS Documentation mentions the following.

By default, a Query operation does not return any data on how much read capacity it consumes.

However, you can specify the ReturnConsumedCapacity parameter in a Query request to obtain this information.

The following are the valid settings for ReturnConsumedCapacity.

NONE-no consumed capacity data is returned.

(This is the default).

TOTAL-the response includes the aggregate number of read capacity units consumed.

INDEXES-the response shows the aggregate number of read capacity units consumed, together with the consumed capacity for each table and index that was accessed.

Because of what the AWS Documentation mentions, all other options are invalid.

For more information on the Query operation, please refer to the below URL-

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Query.html

The correct answer to the question is B. Ensure to set the ReturnConsumedCapacity in the query request to TRUE.

When you execute a query against a DynamoDB table, it consumes a certain amount of capacity in terms of read capacity units (RCUs) and write capacity units (WCUs). DynamoDB measures the capacity consumed by a query in terms of the number of RCUs and WCUs used to satisfy the query. RCUs are consumed when reading data from a DynamoDB table, and WCUs are consumed when writing data to a DynamoDB table.

To measure the capacity consumed by a query, you can use the ReturnConsumedCapacity parameter. When you set this parameter to true in a query request, DynamoDB returns the consumed capacity of the query in the response. You can use this information to optimize the performance of your application and reduce costs by reducing the amount of capacity consumed by your queries.

Option A is incorrect because queries do not return consumed capacity by default. You need to set the ReturnConsumedCapacity parameter to true in the query request to get the consumed capacity.

Option C is incorrect because the TOTAL value of the ReturnConsumedCapacity parameter returns the total capacity consumed by the operation, including all of the capacity consumed by the query and any secondary indexes used to satisfy the query. This value may be higher than the capacity consumed by the query alone.

Option D is incorrect because the Scan operation reads every item in a table or a secondary index, which can be very expensive in terms of consumed capacity. It is not an efficient way to measure the capacity consumed by a query.

Therefore, the correct answer is B. Ensure to set the ReturnConsumedCapacity in the query request to TRUE.