Exam DP-200 topic 2 question 51 discussion

Actual exam question from Microsoft's DP-200

Question #: 51
Topic #: 2

You plan to build a structured streaming solution in Azure Databricks. The solution will count new events in five-minute intervals and report only events that arrive during the interval. The output will be sent to a Delta Lake table.
Which output mode should you use?

A. complete
B. update
C. append

Show Suggested Answer

Suggested Answer: C 🗳️
Append Mode: Only new rows appended in the result table since the last trigger are written to external storage. This is applicable only for the queries where existing rows in the Result Table are not expected to change.
Incorrect Answers:
A: Complete Mode: The entire updated result table is written to external storage. It is up to the storage connector to decide how to handle the writing of the entire table.
B: Update Mode: Only the rows that were updated in the result table since the last trigger are written to external storage. This is different from Complete Mode in that Update Mode outputs only the rows that have changed since the last trigger. If the query doesn't contain aggregations, it is equivalent to Append mode.
Reference:
https://docs.databricks.com/getting-started/spark/streaming.html

by memo43 at May 19, 2021, 8:33 a.m.

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ramelas

3 years, 6 months ago

"The solution will count new events in five-minute intervals and report only events that arrive during the interval." it is COMPLETE, not append

upvoted 1 times

uzairahm

2 years, 11 months ago

It is a delta lake in destination so you could write the complete results to output as well but what would be the criteria of managing in delta lake is not clear so i would go with append as each five minutes interval count results would go in as a separate row in destination

upvoted 1 times

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memo43

4 years ago

answer is CORRECT

upvoted 4 times

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