Exam MCD - Level 1 topic 1 question 65 discussion

A is the correct answer.

* Watermark allows the poll scope to poll for new resources instead of getting the same resource over and over again. * The database table must be ordered so that the "watermark functionality" can move effectively in the ordered list. Watermark stores the current/last picked up "record id." * If the Mule application is shut down, it will store the last picked up "record id" in the Java Object Store and the data will continue to exist in the file. This watermark functionality is valuable and enables developers to have increased transparency. * Developers do not need to create code to handle caching; it is all configurable! * There are two columns and both are unique but user_id can't guaranty sequence whereas date_time will always be in increasing order and table content can easily be ordered on the basis of last processed date_time. So correct answer is: Set the watermark column to the date_time column

Watermark should be set on Primary key, so D should be the answer.

This is a scenario for watermarking, therefore A has to be the answer, not the pointed B option ('On Table Row' doesn't even have a target parameter as seen in https://docs.mulesoft.com/connectors/db/database-documentation)

I am doubtful about option A. Consider a scenario, the user logged in at time A and the row was retrieved by the listener. The same row can be retrieved again if the user logs in later sometime (the logged in column gets updated to the latest time for the same row and possibly greater than watermarking column value), but the question says "each row should be retrieved at most one time". Example: UserId LoginTime 1 10:00 AM At this point of time, watermarking column value = 10:00 AM Later some time same user again logs in then UserId LoginTime 1 12:00 AM This time as the column value is greater than the watermark column value, it will be again retrieved which is against question statement. Is this a valid scenario, can someone please explain? Thanks

A is Correct

A is the correct answer

A is correct

B is the correct answer.

Set the watermark column to the login_date_time column

"Neither column allows duplicate values." if there have two user click in same time, them the timestamp may same. So I think the B is correct.

I wonder why is D incorrect? I would choose both A and D.

A is correct. It is done on column not on value