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Exam Certified Data Engineer Professional topic 1 question 28 discussion

Actual exam question from Databricks's Certified Data Engineer Professional
Question #: 28
Topic #: 1
[All Certified Data Engineer Professional Questions]

A junior data engineer seeks to leverage Delta Lake's Change Data Feed functionality to create a Type 1 table representing all of the values that have ever been valid for all rows in a bronze table created with the property delta.enableChangeDataFeed = true. They plan to execute the following code as a daily job:

Which statement describes the execution and results of running the above query multiple times?

  • A. Each time the job is executed, newly updated records will be merged into the target table, overwriting previous values with the same primary keys.
  • B. Each time the job is executed, the entire available history of inserted or updated records will be appended to the target table, resulting in many duplicate entries.
  • C. Each time the job is executed, the target table will be overwritten using the entire history of inserted or updated records, giving the desired result.
  • D. Each time the job is executed, the differences between the original and current versions are calculated; this may result in duplicate entries for some records.
  • E. Each time the job is executed, only those records that have been inserted or updated since the last execution will be appended to the target table, giving the desired result.
Show Suggested Answer Hide Answer
Suggested Answer: B 🗳️
by asmayassineg at Aug. 2, 2023, 12:40 p.m.

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Ashish7singh2020
21 hours, 46 minutes ago
Selected Answer: B
since start version is 0
upvoted 1 times
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akashdesarda
3 months ago
Selected Answer: B
The starting version is 0, that means in every version entire data will be fetched. It is then append.
upvoted 1 times
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faraaz132
6 months ago
Correct Answer: B (not E) Although it was pretty obvious to me, I still wrote the code to check and yes, it will append the entire change during every write since starting version is mentioned as 0. If in doubt, code it yourselves
upvoted 2 times
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imatheushenrique
8 months ago
("startingVersion", 0) that means the entiry history of table will be read so B.
upvoted 3 times
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PrashantTiwari
12 months ago
B is correct
upvoted 2 times
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kz_data
1 year ago
Selected Answer: B
B is correct
upvoted 2 times
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5ffcd04
1 year, 1 month ago
Selected Answer: B
Correct B
upvoted 1 times
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azurelearn2020
1 year, 1 month ago
Selected Answer: B
correct answer is B.
upvoted 1 times
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[Removed]
1 year, 2 months ago
Selected Answer: E
Considering that we are talking about Change Data Feed and the code is filtering by[ "update_postimage", "insert" ] the column "_change_type", I would go with the option E. Reference: https://docs.delta.io/latest/delta-change-data-feed.html#:~:text=_change_type,update_preimage%20%2C%20update_postimage
upvoted 1 times
5ffcd04
1 year, 1 month ago
Notice option ("startingVersion", 0), which will bring all changes from begining. Hence Answer is B.
upvoted 5 times
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jyothsna12496
1 year, 3 months ago
why is it Not E. It gets newly inserted or updated records
upvoted 1 times
[Removed]
1 year, 2 months ago
I'm with you, follow the reference: https://docs.delta.io/latest/delta-change-data-feed.html#:~:text=_change_type,update_preimage%20%2C%20update_postimage
upvoted 1 times
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5ffcd04
1 year, 1 month ago
Notice .option ("startingVersion", 0), which will bring all changes from begining. Hence Answer is B.
upvoted 1 times
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sturcu
1 year, 3 months ago
Selected Answer: B
correct
upvoted 1 times
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azurearch
1 year, 4 months ago
B is the right answer, sorry.
upvoted 2 times
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azurearch
1 year, 5 months ago
answer is A, because there is a filter as asmayassineg said. Filter filters only existing records from change feed
upvoted 1 times
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asmayassineg
1 year, 6 months ago
sorry, answer is correct B.
upvoted 2 times
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asmayassineg
1 year, 6 months ago
Answer is A, since the df is filtering on updated records using update_postimage filter
upvoted 2 times
mht3336
1 year ago
there is also insert in the filter.
upvoted 1 times
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taif12340
1 year, 5 months ago
it's B: Reading table’s changes, captured by CDF, using spark.read means that you are reading them as a static source. So, each time you run the query, all table’s changes (starting from the specified startingVersion) will be read.
upvoted 6 times
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C (25%)
B (20%)
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