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Exam PL-300 topic 2 question 51 discussion

Actual exam question from Microsoft's PL-300

Question #: 51
Topic #: 2

Note: This question is part of a series of questions that present the same scenario. Each question in the series contains a unique solution that might meet the stated goals. Some question sets might have more than one correct solution, while others might not have a correct solution.

After you answer a question in this section, you will NOT be able to return to it. As a result, these questions will not appear in the review screen.

From Power Query Editor, you profile the data shown in the following exhibit.

The IoT GUID and IoT ID columns are unique to each row in the query.

You need to analyze IoT events by the hour and day of the year. The solution must improve dataset performance.

Solution: You remove the IoT GUID column and retain the IoT ID column.

Does this meet the goal?

A. Yes
B. No

Show Suggested Answer

Suggested Answer: A 🗳️

by GuerreiroJunior at Jan. 10, 2023, 7:47 p.m.

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BillyBobby

Highly Voted 2 years, 2 months ago

Selected Answer: A

There are two requirements to the question - improve the performance and enable the required analysis. Removing the GUID column will do exactly that - it will improve the performance because it is one less column of data to load but it still enables the required analysis given the IOT ID column is equally unique.

upvoted 56 times

Richdata23

1 year, 7 months ago

correct

upvoted 3 times

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Andreas3999

Highly Voted 2 years, 4 months ago

Chatgpt: B. No, removing the IoT GUID column and retaining the IoT ID column will not meet the goal of analyzing IoT events by the hour and day of the year. The IoT GUID and IoT ID columns are both unique identifiers for each row in the query, and removing either of them would result in losing important information about each event. In order to analyze events by the hour and day of the year, it is necessary to split the DateTime column into separate Date and Time columns, as well as retaining the unique identifiers for each event. Removing the IoT GUID column would not improve dataset performance, as it does not have any impact on the analysis or querying of the data.

upvoted 32 times

Burabari

2 years, 2 months ago

This is wrong. The database uses the GUID for performance but PowerBI does not. Power BI only needs one unique column to perform so eliminating the GUID reduces the dataset size and consequently, the performance of PowerBI. ChatGPT is very good at confidently giving wrong answers, smart people know to do their own verification.

upvoted 48 times

Abhi_1526

1 year, 4 months ago

Do not trust chatgpt bindly

upvoted 5 times

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Maniula

1 year, 11 months ago

You're only addressing performance and missing the second part where the events need to analysed by day of the year and hour.

upvoted 7 times

Vaar

1 year, 9 months ago

In my understanding of the question, we are only supposed to increase performance (without affecting the analysis). So removing the GUID column will increase performance without affecting analysis, and is therefore a sorrect solution.

upvoted 2 times

erency3

1 year, 5 months ago

you understanding wrong, it clearly says analyze by hour and day of the year. Given solution only improves performance, you are still not able to do the analysis. You either need to create a calculated column for time, or split the column(best option).

upvoted 3 times

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55884

1 year, 3 months ago

I dont think so. Having IoT ID only already contribute to a unique row. In PowerBI we are able to add index column by the end of the table. Its possible for the user in this question to add his own unique identifier (index) by taking both IoT GUID and IoT DateTime as their unique reference. Hence, since we only want to analyze the DateTime while ensuring a good performance quality, we DO NOT NEED IoT GUID.

upvoted 2 times

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AnnaBi

2 years, 3 months ago

Agree! The IoT GUID and IoT ID columns are keys columns and removing either of them would result in losing important information!

upvoted 5 times

Acrious

1 year, 11 months ago

They are independently unique, they are not a composite key made of up both to be unique.

upvoted 2 times

ApacheKafka

1 year, 11 months ago

They can be made compsite keys though due to their uniquesness.

upvoted 1 times

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semauni

2 years, 2 months ago

But if they are *both* unique for each event, then removing one of them still allows you to identify events. Moreover, you could even remove both if aggregating on the date column (e.g. with a count column).

upvoted 16 times

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Lulu_2022

Most Recent 2 weeks, 2 days ago

Selected Answer: A

✅ Yes, this solution meets the goal. 🧠 Here's why: IoT GUID and IoT ID are both unique identifiers, meaning they likely have high cardinality (i.e., nearly every row has a distinct value). High-cardinality columns consume more memory and compress poorly in Power BI’s in-memory engine (VertiPaq). If only one of them is needed for analysis or relationships (in this case, IoT ID), then removing the other (IoT GUID) helps reduce dataset size and improve performance — without affecting the ability to analyze events by hour or day.

upvoted 1 times

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desibaby09

7 months, 1 week ago

Selected Answer: A

Yes improves dataset performance

upvoted 1 times

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desibaby09

7 months, 2 weeks ago

Selected Answer: B

this doesn't address the time or date

upvoted 1 times

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jaume

8 months ago

Selected Answer: A

Removing one column will reduce data size which will result in an improved performance of the report

upvoted 3 times

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Dani_eL

1 year, 4 months ago

Selected Answer: A

it says : The IoT GUID and IoT ID columns are unique to each row in the query. BOTH UNIQUES to EACH row... So basically each one can be used as primary key for the table. removing the guid column does improve performance. Better to remove the guid because it 's a 16-byte binary data type compared to a unsigned long which is a 4-byte binary data type

upvoted 1 times

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KKPanda77

1 year, 4 months ago

Answer should be NO...

upvoted 1 times

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Dsbuff

1 year, 6 months ago

Selected Answer: A

Yes-A is correct.

upvoted 2 times

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dede1723

1 year, 8 months ago

Selected Answer: B

The goal is to analyze IoT events by the hour and day of the year. The A answer doesn't meet that goal.

upvoted 5 times

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RMUK

1 year, 9 months ago

YES (no data loss and removing one primary key column (as we have 2 here) will help in performance)

upvoted 1 times

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Igetmyrole

1 year, 10 months ago

B is correct. Removing the loT GUID column and retaining the loT ID column will not directly help in analyzing loT events by the hour and day of the year.

upvoted 3 times

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Acrious

1 year, 11 months ago

Selected Answer: A

A. here is the one thing that many are saying "they have to be able to do the analysis". Thats implied already. No where does it say that the solution makes that possible. It says they need to do that AND the solution must make it more performant. Since its clear they can already do that (as there is nothing you can select to change that just by increasing performance), then removing a column would in fact increase performance, regardless if splitting etc would be more performant.

upvoted 2 times

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Maniula

1 year, 11 months ago

Selected Answer: B

There has to be a date column and a time column to perform the analysis by day of the year and by hour. Removing IoT GUID doesn't solve that, it only improves performance but so does splitting the date column. Previous question was YES, this one is NO.

upvoted 6 times

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Bnxyl

1 year, 12 months ago

Selected Answer: A

A because we the ID column can server the purpose of the analysis

upvoted 3 times

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Ahmadbaww

2 years ago

The answer is Yes, having two primary keys in a table is not the best practice.

upvoted 4 times

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vat4444

2 years, 1 month ago

Selected Answer: A

Answer is Yes. This GUID columns is not necessary as the other column plays the role of Id column. As it is a large text column, removing it will significantly reduce the size of the model, thus increase performance

upvoted 4 times

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