Question 57 of 307
Single answerYou are using Google BigQuery as your data warehouse. Your users report that the following simple query is running very slowly, no matter when they run the query:
SELECT country, state, city FROM [myproject:mydataset.mytable] GROUP BY country
You check the query plan for the query and see the following output in the Read section of Stage:1:
What is the most likely cause of the delay for this query?
What is the most likely cause of the delay for this query?AUsers are running too many concurrent queries in the system
BThe [myproject:mydataset.mytable] table has too many partitions
CEither the state or the city columns in the [myproject:mydataset.mytable] table have too many NULL values
✓DMost rows in the [myproject:mydataset.mytable] table have the same value in the country column, causing data skew
✓
Correct Answer: D
Most rows in the [myproject:mydataset.mytable] table have the same value in the country column, causing data skew
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Explanation
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