Find Inactive Threads in DynamoDB

Answer - D.

Such a similar use case is given in the AWS Documentation:

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For example, consider the Thread table that is defined in Creating Tables and Loading Sample Data.

This table is useful for an application such as the AWS Discussion Forums.

The following diagram shows how the items in the table would be organized.

(Not all of the attributes are shown.)

DynamoDB stores all of the items with the same partition key value contiguously.

In this example, given a particular ForumName, a.

Query.

operation could immediately locate all of the threads for that forum.

Within a group of items with the same partition key value, the items are sorted by sort key value.

If the sort key (Subject) is also provided in the query, DynamoDB can narrow down the results that are returned-for example, returning all of the threads in the "S3" forum that have a Subject beginning with the letter "a".

Some requests might require more complex data access patterns.

For example:

Which forum threads get the most views and replies?

Which thread in a particular forum has the largest number of messages?

How many threads were posted in a particular forum within a particular time period?

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Options A and B are incorrect since here we need to query based on the timestamp.

Option C is incorrect because even though this is possible, this is the least efficient way to manage the query.

For more information on this use case, please visit the url.

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

Option D would be the most efficient way to achieve the requirement.

Explanation:

Option A is not the correct choice because it is based on querying the data based on the ThreadID which will not help in identifying the threads which are not getting any traction and no response has been made in 6 months.

Option B is also not the correct choice because querying the data based on the Author will not help in identifying the threads which are not getting any traction and no response has been made in 6 months.

Option C is not the efficient choice because scanning the entire table and searching for the older records would be a time-consuming and resource-intensive process. It would require scanning the entire table, which will take longer and consume more resources, especially with a large number of rows like in this case.

Option D is the correct choice because creating a global secondary index on LastReplytimestamp will help in identifying the threads which are not getting any traction and no response has been made in 6 months. A global secondary index allows you to query the table using an alternate partition key and sort key. In this case, LastReplytimestamp can be used as a partition key or a sort key, depending on the query requirements. The global secondary index will allow the user to quickly retrieve the threads based on the LastReplytimestamp attribute without scanning the entire table.

By creating a global secondary index, the queries will be faster and more efficient because it will be limited to a subset of the table data, which matches the criteria, and the queries will not have to scan the entire table. Therefore, Option D is the most efficient way to achieve the requirement.