PySpark Certification Practice Test 03

Data Engineer Review Notes

Question 1 of 20

📋 Multiple Choice

Question 41

A newly joined Data Engineer reviews the following requirement: "We have customer data and customer address data. Only customers existing in both datasets should appear in the output." Which join type should be recommended?

✓

A. Inner Join

B. Left Join

C. Right Join

D. Full Join

Answer

✅ A. Inner Join

Explanation

### Review Note Inner Join returns only matching records from both datasets.

Answered: 0 / 20

PySpark Certification Practice Test 03

Data Engineer Review Notes

Insightful Saga — Modern Data Engineering Certification Preparation

Question 41

A. Inner Join

B. Left Join

C. Right Join

D. Full Join

Answer: ✅ A. Inner Join

Explanation:

### Review Note Inner Join returns only matching records from both datasets.

Question 42

Review Requirement: "All customers must appear in the output. Address information should appear only when available." Which join should be chosen?

A. Inner Join

B. Left Join

C. Right Join

D. Cross Join

Answer: ✅ B. Left Join

Question 43

Review Requirement: "Return all records from both systems even when no matching key exists." Which join is appropriate?

A. Inner Join

B. Left Join

C. Full Outer Join

D. Semi Join

Answer: ✅ C. Full Outer Join

Question 44

A retail company wants total sales amount by store. Which operation should be performed first?

A. groupBy()

B. filter()

C. drop()

D. cast()

Answer: ✅ A. groupBy()

Question 45

Review Requirement: "Calculate total revenue for each product." Which aggregation function is most appropriate?

A. sum()

B. avg()

C. min()

D. max()

Answer: ✅ A. sum()

Question 46

A banking company wants average account balance by branch. Which aggregation should be recommended?

A. avg()

B. sum()

C. count()

D. max()

Answer: ✅ A. avg()

Question 47

Review Requirement: "Determine how many transactions occurred for each customer." Which aggregation fits best?

A. count()

B. avg()

C. max()

D. first()

Answer: ✅ A. count()

Question 48

A healthcare company wants to know the highest insurance claim amount submitted by each patient. Which function should be used?

A. max()

B. min()

C. avg()

D. count()

Answer: ✅ A. max()

Question 49

A telecom company wants the lowest monthly usage recorded for each customer. Which aggregation is appropriate?

A. min()

B. max()

C. sum()

D. count()

Answer: ✅ A. min()

Question 50

Review Requirement: "Count distinct customers who placed orders." Which solution best fits?

A. countDistinct()

B. count()

C. avg()

D. sum()

Answer: ✅ A. countDistinct()

Question 51

A retail company has: sales_df customers_df The review note states: "Keep only customer records that have sales." Which join type should be evaluated?

A. Left Semi Join

B. Full Join

C. Cross Join

D. Right Join

Answer: ✅ A. Left Semi Join

Explanation:

### Review Note Semi Join returns rows from the left table when a match exists.

Question 52

Review Requirement: "Identify customers that do NOT have any orders." Which join is most suitable?

A. Left Anti Join

B. Inner Join

C. Right Join

D. Full Join

Answer: ✅ A. Left Anti Join

Question 53

A Data Engineer sees: ```python df.groupBy("department").agg(sum("salary")) ``` What business question is being answered?

A. Total salary by department

B. Employee count

C. Maximum salary

D. Duplicate records

Answer: ✅ A. Total salary by department

Question 54

Review Requirement: "Find average monthly sales by region." Which operation sequence is most appropriate?

A. groupBy() + avg()

B. distinct() + count()

C. filter() + orderBy()

D. drop() + cast()

Answer: ✅ A. groupBy() + avg()

Question 55

A logistics company wants shipment statistics by country. Multiple metrics are required: - Total Shipments - Average Cost - Maximum Cost Which feature should be used?

A. agg()

B. distinct()

C. fillna()

D. union()

Answer: ✅ A. agg()

Question 56

A newly hired engineer joins two datasets. Output row count is much larger than expected. The review document shows: No join condition specified. What is the MOST likely issue?

A. Cross Join

B. Broadcast Join

C. Left Join

D. Semi Join

Answer: ✅ A. Cross Join

Question 57

Review Requirement: "Display top-selling stores first." Which operation should be added after aggregation?

A. orderBy(desc())

B. drop()

C. cast()

D. fillna()

Answer: ✅ A. orderBy(desc())

Question 58

A manufacturing company wants total machine downtime by plant. Which operation sequence is most appropriate?

A. groupBy() + sum()

B. filter() + distinct()

C. cast() + union()

D. drop() + orderBy()

Answer: ✅ A. groupBy() + sum()

Question 59

A banking company aggregates billions of transaction records. Only 300 branch-level records are returned. What explains this behavior?

A. Aggregation reduces data volume

B. Data was deleted

C. Partitions were removed

D. Executors failed

Answer: ✅ A. Aggregation reduces data volume

Question 60

A Senior Data Engineer reviews an ETL design: 1. Join customer data 2. Join transaction data 3. Aggregate spending 4. Publish customer metrics What is the PRIMARY business purpose of these operations?

A. Convert detailed records into meaningful business insights

B. Increase partitions

C. Create executors

D. Reduce cluster memory

Answer: ✅ A. Convert detailed records into meaningful business insights

Explanation:

### Review Note Joins combine related datasets, while aggregations summarize data into business-friendly metrics. --- --- title: PySpark Certification Practice Test 04 description: Window Functions and Analytical Processing --- # PySpark Certification Practice Test 04