Quiz Space

Introduction to Big Data · End Term · 13 Apr 2025 · January 2025 term · Set 1-5

Question 16: You are given the task of improving the performance of a…

Question 16

+4 marksOne or more correct options

You are given the task of improving the performance of a Spark SQL program that is doing a simple count after a series of transformations. You suspect that the culprit is the main transformation job in the program. When you run EXPLAIN on that SQL, you see that Spark wrongly estimates that there are only 10 values for the key on which the main transformation job is hinged upon, whereas in reality the underlying data has a million values for that key. What actions would you perform from the below to increase the estimation accuracy?

Select all that apply.

  1. A

    Create all tables as external tables.

  2. B

    Ensure cost based optimizer (CBO) is ON.

  3. C

    Partition all tables on the same key on which the aggregate is happening.

  4. D

    Run ANALYZE on all tables to ensure the right estimates are available to theoptimizer.

  5. E

    Cache the table in a step with actions ahead of the SQL statement that is theculprit.

Show answer

Correct answers

  • B

    Ensure cost based optimizer (CBO) is ON.

  • D

    Run ANALYZE on all tables to ensure the right estimates are available to theoptimizer.

  • E

    Cache the table in a step with actions ahead of the SQL statement that is theculprit.

See the whole paperTake it as a mock test

Question 16 of 19 in the IIT Madras BS Introduction to Big Data (Intro to Big Data) End Term paper sat on 13 Apr 2025, in the January 2025 term (IIT M IMPROVEMENT FN EXAM QIM2 13 Apr). It carries 4 marks.

This question was also asked in

More questions from this paper

  1. Q1At the onset of every festive season, there is a surge in quick commerce orders (i.e. orders delivered within 15 minute…
  2. Q2You are given a Spark program that runs on a Google Dataproc cluster on a daily schedule starting execution at 7AM runn…
  3. Q3You are asked to build a recommendation engine for an offline store at the checkout counter, using a combination of clo…
  4. Q4Consider a file “data.bin” which is formatted as follows: every data record has 10 key-value pairs of the format “key,v…
  5. Q5You join the data engineering team at a company that has good big data expertise already. Your first assignment is to c…
  6. Q6What happens when a Spark Structured Streaming pipeline operating with Kafka as source and console output as target is …
  7. Q7A big data streaming application that uses Kafka as source is observed to be really lagging behind currently live data.…
  8. Q8A company with headquarters (HQ) in the Middle East operates on a Sunday-Thursday weekday schedule with Friday \& Satur…
  9. Q9You are appointed as a Data Engineer in a company that has a legacy reporting application written in Java which suffers…
  10. Q10Fielder on the midwicket boundary is wearing a smart watch. Unlike other smart watches, this one is unique in that it h…
  11. Q11Suppose there’s a new transformer model from Facebook that is orders of magnitude smaller than mobilenet_v2 and has a b…
  12. Q12You are given a Spark Streaming pipeline that invokes a pre-trained DL model for every image it receives as input and p…
  13. Q13Consider a Structured Streaming application running on Google Dataproc firing up every 10 seconds, consuming any number…
  14. Q14Let us say we are using structured streaming for continuously reading data from Kafka and storing the results back into…
  15. Q15Observe the below image showing a possible implementation of Kafka or Google Pub/Sub and select the options that are tr…
  16. Q17Which of the following are best practices associated with Streaming applications?
  17. Q18What are some capabilities common to both “streaming processing” \& “batch processing” when using Spark for big data?
  18. Q19Which of the following is true?