Databricks Certified Data Engineer Quiz part 3

A data engineer has realized that the data files associated with a Delta table are incredibly small. They want to compact the small files to form larger files to improve performance. Which keyword can be used to compact the small files?

• OPTIMIZE

• VACUUM

• COMPACTION

• REPARTITION

A data engineer wants to create a data entity from a couple of tables. The data entity must be used by other data engineers in other sessions. It also must be saved to a physical location. Which of the following data entities should the data engineer create?

• Table

• Function

• View

• Temporary view

A data engineer runs a statement every day to copy the previous day’s sales into the table transactions. Each day’s sales are in their own file in the location "/transactions/raw". Today, the data engineer runs the following command to complete this task: After running the command today, the data engineer notices that the number of records in table transactions has not changed. What explains why the statement might not have copied any new records into the table?

• The format of the files to be copied were not included with the FORMAT_OPTIONS keyword.

• The COPY INTO statement requires the table to be refreshed to view the copied rows.

• The previous day’s file has already been copied into the table.

• The PARQUET file format does not support COPY INTO.

Which command can be used to write data into a Delta table while avoiding the writing of duplicate records?

• DROP

• INSERT

• MERGE

• APPEND

A data analyst has created a Delta table sales that is used by the entire data analysis team. They want help from the data engineering team to implement a series of tests to ensure the data is clean. However, the data engineering team uses Python for its tests rather than SQL. Which command could the data engineering team use to access sales in PySpark?

• SELECT * FROM sales

• spark.table("sales")

• spark.sql("sales")

• spark.delta.table("sales")

A data engineer has created a new database using the following command: CREATE DATABASE IF NOT EXISTS customer360; In which location will the customer360 database be located?

• dbfs:/user/hive/database/customer360

• dbfs:/user/hive/warehouse

• dbfs:/user/hive/customer360

• dbfs:/user/hive/database

A data engineer is attempting to drop a Spark SQL table my_table and runs the following command: DROP TABLE IF EXISTS my_table; After running this command, the engineer notices that the data files and metadata files have been deleted from the file system. What is the reason behind the deletion of all these files?

• The table was managed

• The table's data was smaller than 10 GB

• The table did not have a location

• The table was external

A data engineer needs to create a table in Databricks using data from a CSV file at location /path/to/csv. They run the following command: Which of the following lines of code fills in the above blank to successfully complete the task?

• FROM "path/to/csv"

• USING CSV

• FROM CSV

• USING DELTA

What is a benefit of creating an external table from Parquet rather than CSV when using a CREATE TABLE AS SELECT statement?

• Parquet files can be partitioned

• Parquet files will become Delta tables

• Parquet files have a well-defined schema

• Parquet files have the ability to be optimized

Which SQL keyword can be used to convert a table from a long format to a wide format?

• TRANSFORM

• PIVOT

• SUM

• CONVERT