Investigating and Analyzing Query Performance in Amazon DocumentDB

Answer: D.

Option A is incorrect because CloudWatch logs do not contain details of DocumentDB query execution plans.

Option B is incorrect because CloudTrail is a log of AWS services API activity.

It cannot be used for monitoring and analyzing the performance of DocumentDB databases.

Option C is incorrect because AWS X-Ray is used for debugging and tracing requests in microservices applications.

Option D is CORRECT because db.runCommand can be used with explain() method to provide a detailed execution plan of a query and provide insight into the query performance.

Reference:

https://docs.aws.amazon.com/documentdb/latest/developerguide/user_diagnostics.html#user_diagnostics-query_plan

To investigate the query execution plan and analyze the query performance of an Amazon DocumentDB cluster, a database specialist can use the following approaches:

A. CloudWatch Logs: CloudWatch Logs can provide insight into the DocumentDB cluster's activity, such as query log entries, system metrics, and error logs. By analyzing these logs, a database specialist can identify slow-running queries and take the necessary actions to optimize them. However, CloudWatch Logs do not provide a detailed analysis of the query execution plan.

B. CloudTrail Events: CloudTrail Events capture API calls made to the DocumentDB cluster, including queries. Database specialists can use CloudTrail to monitor query activity and identify the slowest queries. However, CloudTrail does not provide a detailed analysis of the query execution plan.

C. AWS X-Ray: AWS X-Ray is a service that helps trace requests made to applications running on AWS infrastructure. Database specialists can use X-Ray to trace the execution of DocumentDB queries and identify performance bottlenecks. With X-Ray, they can visualize the query execution path and see where the query spent the most time. X-Ray can also help identify issues related to network latency and service dependencies.

D. MongoDB explain() method: Amazon DocumentDB is compatible with the MongoDB API, and as such, it supports the explain() method. The explain() method provides a detailed analysis of the query execution plan, including the indexes used, the number of documents scanned, and the time spent on each stage of the query. With this information, database specialists can identify performance issues and optimize queries accordingly.

In summary, to investigate the query execution plan and analyze the query performance of an Amazon DocumentDB cluster, a database specialist can use AWS X-Ray or the MongoDB explain() method. While CloudWatch Logs and CloudTrail Events can help monitor query activity and identify slow queries, they do not provide a detailed analysis of the query execution plan.