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Describe core data concepts →mediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is to remove duplicate OrderIDs by counting them. This is correct because a Data Factory mapping data flow uses an aggregate transformation to group data by a key column—in this case, OrderID—and then applies a count, which inherently deduplicates the data by collapsing all rows with the same OrderID into a single row with a count. On the Microsoft Azure Data Fundamentals DP-900 exam, this scenario tests your understanding of how mapping data flows transform data without writing code, specifically using aggregates for deduplication rather than filters, joins, or pivots. A common trap is confusing an aggregate that counts with a filter that removes rows, but remember: an aggregate groups and summarizes, while a filter only selects rows. For a quick memory tip, think “Aggregate to deduplicate, filter to eliminate.”

DP-900 Describe core data concepts Practice Question

This DP-900 practice question tests your understanding of describe core data concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

Exhibit

Refer to the exhibit.

```json
{
  "properties": {
    "folder": "transform",
    "type": "MappingDataFlow",
    "typeProperties": {
      "sources": [
        {
          "name": "source1",
          "dataset": {
            "referenceName": "SalesCSV",
            "type": "DatasetReference"
          },
          "sourceSettings": {
            "format": "DelimitedText",
            "delimiter": ","
          }
        }
      ],
      "sinks": [
        {
          "name": "sink1",
          "dataset": {
            "referenceName": "SalesParquet",
            "type": "DatasetReference"
          },
          "sinkSettings": {
            "format": "Parquet"
          }
        }
      ],
      "transformations": [
        {
          "name": "RemoveDuplicates",
          "type": "Aggregate",
          "inputs": ["source1"],
          "aggregates": [
            {"column": "OrderID", "operation": "count", "output": "Count"}
          ]
        }
      ]
    }
  }
}
```

You are reviewing a Data Factory mapping data flow definition. What is the primary purpose of this data flow?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "primary"

    Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

Question 1mediummultiple choice
Full question →

Exhibit

Refer to the exhibit.

```json
{
  "properties": {
    "folder": "transform",
    "type": "MappingDataFlow",
    "typeProperties": {
      "sources": [
        {
          "name": "source1",
          "dataset": {
            "referenceName": "SalesCSV",
            "type": "DatasetReference"
          },
          "sourceSettings": {
            "format": "DelimitedText",
            "delimiter": ","
          }
        }
      ],
      "sinks": [
        {
          "name": "sink1",
          "dataset": {
            "referenceName": "SalesParquet",
            "type": "DatasetReference"
          },
          "sinkSettings": {
            "format": "Parquet"
          }
        }
      ],
      "transformations": [
        {
          "name": "RemoveDuplicates",
          "type": "Aggregate",
          "inputs": ["source1"],
          "aggregates": [
            {"column": "OrderID", "operation": "count", "output": "Count"}
          ]
        }
      ]
    }
  }
}
```

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Remove duplicate OrderIDs by counting them

Option C is correct because the data flow reads CSV, performs an aggregate (count by OrderID) to remove duplicates, and outputs Parquet. Option A is wrong because it does not filter rows. Option B is wrong because it doesn't join. Option D is wrong because it doesn't pivot.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • ✗

    Pivot the data by OrderID

    Why it's wrong here

    No pivot transformation is used.

  • ✗

    Filter rows where OrderID is null

    Why it's wrong here

    No filter transformation is used.

  • ✓

    Remove duplicate OrderIDs by counting them

    Why this is correct

    The aggregate counts OrderID, effectively identifying duplicates.

    Clue confirmation

    The clue word "primary" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • ✗

    Merge two data sources

    Why it's wrong here

    Only one source is defined.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.

Detailed technical explanation

How to think about this question

This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.
  • Use explanations to understand the rule behind the answer.

TExam Day Tips

  • Underline the problem statement mentally.
  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.

What to study next

Got this wrong? Here's your next step.

Identify which DP-900 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.

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FAQ

Questions learners often ask

What does this DP-900 question test?

Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Remove duplicate OrderIDs by counting them — Option C is correct because the data flow reads CSV, performs an aggregate (count by OrderID) to remove duplicates, and outputs Parquet. Option A is wrong because it does not filter rows. Option B is wrong because it doesn't join. Option D is wrong because it doesn't pivot.

What should I do if I get this DP-900 question wrong?

Identify which DP-900 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.

Are there clue words in this question I should notice?

Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 20, 2026

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This DP-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DP-900 exam.