Task 3.4: Ensure Data Quality DEA-C01 Practice Questions (Page 2)

Questions 6–10

1. 6foundation · easy

   A data engineer needs to select a sample of customer records for a survey such that the sample proportionally represents different age groups. Which sampling technique should be used?

   • ARandom sampling
   • BConvenience sampling
   • CSystematic sampling
   • DStratified sampling
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2. 7foundation · easy

   A data engineer is writing a PySpark script in AWS Glue to process streaming data. Which code snippet correctly validates that the 'customer_id' field is not empty before writing the record to the output?

   • Adf.filter(df['customer_id'] != '')
   • Bdf.select(df['customer_id'])
   • Cdf.withColumn('customer_id', when(col('customer_id').isNull(), 'unknown'))
   • Ddf.dropDuplicates(['customer_id'])
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4. 8foundation · easy

   While investigating data consistency issues in AWS Glue DataBrew, a data engineer notices that the 'date' column in one dataset is stored as a string in 'YYYY-MM-DD' format, while in another dataset it is stored as a string in 'MM/DD/YYYY' format. Which DataBrew feature should be used to standardize these values for comparison?

   • ADataBrew recipes
   • BData lineage
   • CData quality rules
   • DData profiling
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5. 9foundation · easy

   A data engineer is running an AWS Glue ETL job that joins two large datasets on a 'country' column. The job is slow because a few countries have millions of records while most have few. Which mechanism can help mitigate the impact of this data skew?

   • AIncrease the number of workers in the Glue job
   • BUse a salted join key to distribute the skewed keys across more partitions
   • CDisable speculative execution
   • DUse a broadcast join to send the smaller dataset to all workers
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6. 10expert · hard

   A company runs an AWS Glue ETL job that processes log data. The job uses a GROUP BY on a 'country' column, and one country has significantly more data than others. The job is slow and often fails due to memory issues on the skewed partition. The team needs to make the job more reliable and faster. Which approach should they use?

   • AIncrease the memory of the Glue workers to handle the skewed partition.
   • BFilter out the skewed country from the analysis.
   • CUse a two-phase aggregation: first aggregate with a salted key, then aggregate the results without the salt.
   • DUse a broadcast join to distribute the country dimension to all nodes.
   Reveal Solution Discussion Select an answer first