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Databricks - Data Engineer Associate Practice Exam 1 questions with correct answers
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Databricks - Data Engineer Associate Practice Exam 1 questions with correct answers
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Databricks - Data Engineer AssociatePractice Exam 1 questions with correct
answers
You were asked to create a table that can store the below data, <orderTime> is a timestamp
x x x x x x x x x x x x x x x x
but the finance team when they query this data normally prefer the <orderTime> in date
x x x x x x x x x x x x x x x
format, you would like to create a calculated column that can convert the <orderTime>
x x x x x x x x x x x x x x
column timestamp datatype to date and store it, fill in the blank to complete the DDL.
x x x x x x x x x x x x x x x x
CREATE TABLE orders ( x x x
x orderId int, x
x orderTime timestamp, x
x orderdate date _____________________________________________ ,
x x x
x units int) x
A. AS DEFAULT (CAST(orderTime as DATE))
x x x x x
B. GENERATED ALWAYS AS (CAST(orderTime as DATE))
x x x x x x
C. GENERATED DEFAULT AS (CAST(orderTime as DATE))
x x x x x x
D. AS (CAST(orderTime as DATE))
x x x x
E. Delta lake does not support calculated columns, value should be inserted into the table as
x x x x x x x x x x x x x x x
part of the ingestion process - ANSWER: ➡ B. GENERATED ALWAYS AS (CAST(orderTime as
x x x x x x x xx x x x x x x
DATE))
x
Explanation
The answer is, GENERATED ALWAYS AS (CAST(orderTime as DATE))
x x x x x x x x
https://docs.microsoft.com/en-us/azure/databricks/delta/delta-batch#--use-generated-
columns
,Delta Lake supports generated columns which are a special type of columns whose values are
x x x x x x x x x x x x x x
automatically generated based on a user-specified function over other columns in the Delta
x x x x x x x x x x x x x
table. When you write to a table with generated columns and you do not explicitly provide
x x x x x x x x x x x x x x x x
values for them, Delta Lake automatically computes the values.
x x x x x x x x x
Note: Databricks also supports partitioning using generated column
x x x x x x x
The data engineering team noticed that one of the job fails randomly as a result of using spot
x x x x x x x x x x x x x x x x x
instances, what feature in Jobs/Tasks can be used to address this issue so the job is more stable
x x x x x x x x x x x x x x x x x x
when using spot instances?
x x x x
A. Use Databrick REST API to monitor and restart the job
x x x x x x x x x x
B. Use Jobs runs, active runs UI section to monitor and restart the job
x x x x x x x x x x x x x
C. Add second task and add a check condition to rerun the first task if it fails
x x x x x x x x x x x x x x x x
D. Restart the job cluster, job automatically restarts
x x x x x x x
E. Add a retry policy to the task - ANSWER: ➡ E. Add a retry policy to the task
x x x x x x x x x xx x x x x x x x x
The answer is, Add a retry policy to the task
x x x x x x x x x
Tasks in Jobs support Retry Policy, which can be used to retry a failed tasks, especially when
x x x x x x x x x x x x x x x x
using spot instance it is common to have failed executors or driver.
x x x x x x x x x x x x
What is the main difference between AUTO LOADER and COPY INTO?
x x x x x x x x x x
A. COPY INTO supports schema evolution.
x x x x x
B. AUTO LOADER supports schema evolution.
x x x x x
C. COPY INTO supports file notification when performing incremental loads.
x x x x x x x x x
D. AUTO LOADER supports reading data from Apache Kafka
x x x x x x x x
E, AUTO LOADER Supports file notification when performing incremental loads. - ANSWER: ➡
x x x x x x x x x x x xx
E, AUTO LOADER Supports file notification when performing incremental loads.
x x x x x x x x x x
,Explanation
Auto loader supports both directory listing and file notification but COPY INTO only supports
x x x x x x x x x x x x x
directory listing.
x x
Auto loader file notification will automatically set up a notification service and queue service
x x x x x x x x x x x x x
that subscribe to file events from the input directory in cloud object storage like Azure blob
x x x x x x x x x x x x x x x x
storage or S3. File notification mode is more performant and scalable for large input
x x x x x x x x x x x x x x
directories or a high volume of files.
x x x x x x x
Auto Loader and Cloud Storage Integration
x x x x x
Auto Loader supports a couple of ways to ingest data incrementally
x x x x x x x x x x
Directory listing - List Directory and maintain the state in RocksDB, supports incremental file
x x x x x x x x x x x x x
listing
x
File notification - Uses a trigger+queue to store the file notification which can be later used to
x x x x x x x x x x x x x x x x
retrieve the file, unlike Directory listing File notification can scale up to millions of files per day.
x x x x x x x x x x x x x x x x x
[OPTIONAL]
Auto Loader vs COPY INTO?
x x x x
Auto Loader x
Auto Loader incrementally and efficiently processes new data files as they arrive in cloud
x x x x x x x x x x x x x
storage without any additional setup. Auto Loader provides a new Structured Streaming
x x x x x x x x x x x x
source called cloudFiles. Given an input directory path on the cloud file storage, the cloudFiles
x x x x x x x x x x x x x x x
source automatically processes new files as they arrive, with the option of also processing
x x x x x x x x x x x x x x
existing files in that directory.
x x x x x
When to use Auto Loader instead of the COPY INTO?
x x x x x x x x x
, You want to load data from a file location that contains files in the order of millions or higher.
x x x x x x x x x x x x x x x x x x
Auto Loader can discover files more efficiently than the COPY INTO SQL command and can split
x x x x x x x x x x x x x x x x
file processing into multiple batches.
x x x x x
You do not plan to load subsets of previously uploaded files. With Auto Loader, it can be more
x x x x x x x x x x x x x x x x x
difficult to reprocess subsets of files. However, you can use the COPY INTO SQL
x x x x x x x x x x x x x x
Why does AUTO LOADER require schema location?
x x x x x x
A. Schema location is used to store user provided schema
x x x x x x x x x
B. Schema location is used to identify the schema of target table
x x x x x x x x x x x
C. AUTO LOADER does not require schema location, because its supports Schema evolution
x x x x x x x x x x x x
D. Schema location is used to store schema inferred by AUTO LOADER
x x x x x x x x x x x
E. Schema location is used to identify the schema of target table and source table - ANSWER: ➡
x x x x x x x x x x x x x x x x xx
D. Schema location is used to store schema inferred by AUTO LOADER
x x x x x x x x x x x x
Explanation
The answer is, Schema location is used to store schema inferred by AUTO LOADER, so the next
x x x x x x x x x x x x x x x x
time AUTO LOADER runs faster as does not need to infer the schema every single time by trying
x x x x x x x x x x x x x x x x x x
to use the last known schema.
x x x x x x
Auto Loader samples the first 50 GB or 1000 files that it discovers, whichever limit is crossed
x x x x x x x x x x x x x x x x
first. To avoid incurring this inference cost at every stream start up, and to be able to provide a
x x x x x x x x x x x x x x x x x x x
stable schema across stream restarts, you must set the option cloudFiles.schemaLocation.
x x x x x x x x x x x
Auto Loader creates a hidden directory _schemas at this location to track schema changes to
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the input data over time.
x x x x x
The below link contains detailed documentation on different options
x x x x x x x x
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