Free Databricks Associate-Developer-Apache-Spark Exam Dumps Questions & Answers

Which of the following DataFrame methods is classified as a transformation?

• A.DataFrame.count()
• B.DataFrame.select()
• C.DataFrame.foreach()
• D.DataFrame.show()
• E.DataFrame.first()

The code block displayed below contains an error. The code block is intended to return all columns of DataFrame transactionsDf except for columns predError, productId, and value. Find the error.
Excerpt of DataFrame transactionsDf:
transactionsDf.select(~col("predError"), ~col("productId"), ~col("value"))

• A.The column names in the select operator should not be strings and wrapped in the col operator, so they should be expressed like select(~col(predError), ~col(productId), ~col(value)).
• B.The select operator should be replaced with the deselect operator.
• C.The select operator should be replaced by the drop operator.
• D.The select operator should be replaced by the drop operator and the arguments to the drop operator should be column names predError, productId and value wrapped in the col operator so they should be expressed like drop(col(predError), col(productId), col(value)).
• E.The select operator should be replaced by the drop operator and the arguments to the drop operator should be column names predError, productId and value as strings.
  (Correct)

The code block displayed below contains an error. The code block should merge the rows of DataFrames transactionsDfMonday and transactionsDfTuesday into a new DataFrame, matching column names and inserting null values where column names do not appear in both DataFrames. Find the error.
Sample of DataFrame transactionsDfMonday:
1.+-------------+---------+-----+-------+---------+----+
2.|transactionId|predError|value|storeId|productId| f|
3.+-------------+---------+-----+-------+---------+----+
4.| 5| null| null| null| 2|null|
5.| 6| 3| 2| 25| 2|null|
6.+-------------+---------+-----+-------+---------+----+
Sample of DataFrame transactionsDfTuesday:
1.+-------+-------------+---------+-----+
2.|storeId|transactionId|productId|value|
3.+-------+-------------+---------+-----+
4.| 25| 1| 1| 4|
5.| 2| 2| 2| 7|
6.| 3| 4| 2| null|
7.| null| 5| 2| null|
8.+-------+-------------+---------+-----+
Code block:
sc.union([transactionsDfMonday, transactionsDfTuesday])

• A.Instead of the Spark context, transactionDfMonday should be called with the union method.
• B.The DataFrames' RDDs need to be passed into the sc.union method instead of the DataFrame variable names.
• C.Instead of union, the concat method should be used, making sure to not use its default arguments.
• D.Instead of the Spark context, transactionDfMonday should be called with the join method instead of the union method, making sure to use its default arguments.
• E.Instead of the Spark context, transactionDfMonday should be called with the unionByName method instead of the union method, making sure to not use its default arguments.

Which of the following code blocks concatenates rows of DataFrames transactionsDf and transactionsNewDf, omitting any duplicates?

• A.transactionsDf.concat(transactionsNewDf).unique()
• B.transactionsDf.union(transactionsNewDf).distinct()
• C.spark.union(transactionsDf, transactionsNewDf).distinct()
• D.transactionsDf.union(transactionsNewDf).unique()
• E.transactionsDf.join(transactionsNewDf, how="union").distinct()

The code block displayed below contains an error. The code block should save DataFrame transactionsDf at path path as a parquet file, appending to any existing parquet file. Find the error.
Code block:

• A.The code block is missing a bucketBy command that takes care of partitions.
• B.save() is evaluated lazily and needs to be followed by an action.
• C.Given that the DataFrame should be saved as parquet file, path is being passed to the wrong method.
• D.The mode option should be omitted so that the command uses the default mode.
• E.The code block is missing a reference to the DataFrameWriter.
• F.transactionsDf.format("parquet").option("mode", "append").save(path)