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RAN-DBDEA-00274
Ranvier · DBDEA

Exam DBDEA Topics: troubleshooting Difficulty: medium

A PySpark job reads a large Delta table that was written as many small files. The read stage schedules over 4,000 tasks that each finish in a fraction of a second, and most of the stage time goes to scheduling overhead. Which setting controls how much data each read task processes, so the small files can be packed into fewer tasks?

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  1. A. `spark.sql.files.maxPartitionBytes`, which however only influences the size of the files written by the job's outputs
  2. B. The cluster's core count, because input splits are derived solely from the number of worker nodes and no tunable target size exists
  3. C. The split target, which must never be raised, because larger tasks always degrade reads in every workload
  4. D. `spark.sql.files.maxPartitionBytes`, which sets how many bytes are packed into a single read partition (128 MB by default)
Reveal answer

Correct answer: `spark.sql.files.maxPartitionBytes`, which sets how many bytes are packed into a single read partition (128 MB by default)

Reference: https://docs.databricks.com/aws/en/optimizations/spark-ui-guide/

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Official Answer (D): `spark.sql.files.maxPartitionBytes`, which sets how many bytes are packed into a single read partition (128 MB by default)

Ranvier · DBDEA

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