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Data engineering interview · Media, Streaming & Telecom

Warner Bros. Discovery

A hard CoderPad SQL, a five-transformation pandas/PySpark round + APIs, and an AWS Glue/Kinesis + governance focus.

Stages: 53 with reported questions
Difficulty: Not rated
Cloud: AWS-heavy
Evidence: 1 of 2sources are first-hand

What Warner Bros. Discovery does

And what its data engineers work with.

Business: Media / streaming (Max/HBO)
Platform: AWS-heavy: Glue, Kinesis, S3; Spark
Stack named in its interviews: SQL
Python
PySpark
AWS (Glue/Kinesis)
APIs

The loop

Stages in the order candidates meet them.

01Phone screen
02Hard SQL (CoderPad)
035 transformations + API
04Final (experience + Spark + design)
05Offer

5 stages. 3 rounds have reported questions, described below.

What each round expects

The topics it covers and the questions candidates reported.

ROUND 01
SQL
Medium confidence
- SQL
2 reported questions. See them below
ROUND 02
Transformations / PySpark
High confidence
- Spark
2 reported questions. See them below
ROUND 03
Final
Medium confidence
- Design
- Spark
1 reported question. See them below

Reported interview questions

By round. Questions marked Expected are written from the company's standards.

Reported from accounts and guides, by round

SQLMedium confidence

A hard-level SQL question on CoderPadPractise SQL
Window functions, complex joins, optimizationPractise SQL

Transformations / PySparkHigh confidence

A dataset with five transformations to write in pandas or PySparkPractise Apache Spark
3 questions on APIsPractise Apache Spark

FinalMedium confidence

Past experience, Spark optimization, pipeline design (partly HR)Practise Apache Spark

Expected written from Warner Bros. Discovery's standards

Nobody reported these exact questions at Warner Bros. Discovery. They are the questions a loop for each of its top topics is known to ask, so prepare for them as likely, not as confirmed.

What is a shuffle, and how would you make a job shuffle less?Spark
One hot key makes a join slow. What do you do?Spark
Return the top 3 rows per group, and say what happens on ties.SQL
Find the latest row per key in a table that has duplicates.SQL
Design a daily pipeline from an app database to a warehouse that is safe to rerun.Design
How would you handle late and duplicate events?Design
When would you choose Airflow, and when would you not?Cloud and tools
How do you load files from object storage into a warehouse?Cloud and tools
Tell me about a pipeline you owned that failed in production.Behavioral
Describe a disagreement about a design, and how it ended.Behavioral

Must know

Ranked by how much of the evidence points at each topic.

Spark and big dataReported2 reported questions across 2 rounds
SQLReported2 reported questions across 1 round
Pipeline and system designReported1 reported question across 1 round
Cloud and toolsIn the prioritiesNamed in the prep priorities
Behavioral and communicationIn the prioritiesNamed in the prep priorities

What matters most

Do the first group before the second.

Hard SQL (CoderPad-style)
Do first (3)
Transformations in pandas/PySpark
AWS Glue/Kinesis + governance; Spark optimization + pipeline design
APIs
Then
Content/ad-yield domain metrics
Behavioral

Rejection patterns

Why candidates were turned down, as reported.

Ignoring the governance slice
Weak hard-SQL
SQL is named in 37 of 50 company accounts.
Shaky pandas/PySpark transformations
Spark is named in 25 of 50 company accounts.
No AWS Glue/Kinesis experience
Cloud and tools is named in 4 of 50 company accounts.

Reported experiences

1 reported, 4 composite. Each opens and closes. Composites are labelled.

5 accounts

Data Engineer II (~3 YoE)Date not statedReportedCandidate account
Hard SQL on CoderPad, then a dataset task with five transformations (pandas or PySpark) and three API questions, then a final round on past work, Spark tuning and pipeline design.
What to take from it Practise transforming a dataset in pandas or PySpark under time.
Composite walkthroughs. Built from the company's documented loop, not from one person's account.
The SQL roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: A hard-level SQL question on CoderPad; Window functions, complex joins, optimization.
What to take from it Practise these questions before you reach this round.
Questions named
- A hard-level SQL question on CoderPad
- Window functions, complex joins, optimization
The Transformations / PySpark roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: A dataset with five transformations to write in pandas or PySpark; 3 questions on APIs.
What to take from it Practise these questions before you reach this round.
Questions named
- A dataset with five transformations to write in pandas or PySpark
- 3 questions on APIs
The Final roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: Past experience, Spark optimization, pipeline design (partly HR).
What to take from it Practise these questions before you reach this round.
Questions named
- Past experience, Spark optimization, pipeline design (partly HR)
The whole loop, start to finishDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Candidates go through 5 stages, in this order: Phone screen, then Hard SQL (CoderPad), then 5 transformations + API, then Final (experience + Spark + design), then Offer.
What to take from it Know the order, so that no stage surprises you.

Sources and how sure we are

AWS Glue/Kinesis + the governance slice are commonly-overlooked prep areas.

growdataskills — WBD Data Engineer II, 3 YoE
datainterview — Warner Bros. Data Engineer guide (guide, not a first-hand account)

Rehearse the Warner Bros. Discovery loop

Their reported questions, one at a time, against a stopwatch.

SQL · 1 of 5

A hard-level SQL question on CoderPad

Out loud, in order: clarify, build it, check it, explain it.

Practise SQL

00:00

Your preparation plan

Pick your level and the weeks you have.

Built from what Warner Bros. Discovery asks, strongest first. For the wider basics at your level, follow the Mid level plan alongside it.

Week 1
Spark and big data
Read: Spark chapters Drill: Spark playground Say it aloud: Spark questions Full plan: Ace the Spark round
SQL
Read: SQL chapters Drill: SQL practice Say it aloud: SQL questions Full plan: Ace the SQL round
Pipeline and system design
Read: Data pipeline chapters Drill: Pipeline practice Say it aloud: Data pipeline questions Full plan: Ace the pipeline round
Cloud and tools
Read: Data pipeline chapters Say it aloud: AWS questions
Behavioral and communication
Read: Behavioral storytelling Say it aloud: Behavioral questions
Week 2
Rehearse the Warner Bros. Discovery loop
Run the question deckThen repeat your weakest topic once more.

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All interview experiences

Data engineering interview · Media, Streaming & Telecom

Warner Bros. Discovery

A hard CoderPad SQL, a five-transformation pandas/PySpark round + APIs, and an AWS Glue/Kinesis + governance focus.

Stages: 53 with reported questions
Difficulty: Not rated
Cloud: AWS-heavy
Evidence: 1 of 2sources are first-hand

What Warner Bros. Discovery does

And what its data engineers work with.

Business: Media / streaming (Max/HBO)
Platform: AWS-heavy: Glue, Kinesis, S3; Spark
Stack named in its interviews: SQL
Python
PySpark
AWS (Glue/Kinesis)
APIs

The loop

Stages in the order candidates meet them.

01Phone screen
02Hard SQL (CoderPad)
035 transformations + API
04Final (experience + Spark + design)
05Offer

5 stages. 3 rounds have reported questions, described below.

What each round expects

The topics it covers and the questions candidates reported.

ROUND 01
SQL
Medium confidence
- SQL
2 reported questions. See them below
ROUND 02
Transformations / PySpark
High confidence
- Spark
2 reported questions. See them below
ROUND 03
Final
Medium confidence
- Design
- Spark
1 reported question. See them below

Reported interview questions

By round. Questions marked Expected are written from the company's standards.

Reported from accounts and guides, by round

SQLMedium confidence

A hard-level SQL question on CoderPadPractise SQL
Window functions, complex joins, optimizationPractise SQL

Transformations / PySparkHigh confidence

A dataset with five transformations to write in pandas or PySparkPractise Apache Spark
3 questions on APIsPractise Apache Spark

FinalMedium confidence

Past experience, Spark optimization, pipeline design (partly HR)Practise Apache Spark

Expected written from Warner Bros. Discovery's standards

Nobody reported these exact questions at Warner Bros. Discovery. They are the questions a loop for each of its top topics is known to ask, so prepare for them as likely, not as confirmed.

What is a shuffle, and how would you make a job shuffle less?Spark
One hot key makes a join slow. What do you do?Spark
Return the top 3 rows per group, and say what happens on ties.SQL
Find the latest row per key in a table that has duplicates.SQL
Design a daily pipeline from an app database to a warehouse that is safe to rerun.Design
How would you handle late and duplicate events?Design
When would you choose Airflow, and when would you not?Cloud and tools
How do you load files from object storage into a warehouse?Cloud and tools
Tell me about a pipeline you owned that failed in production.Behavioral
Describe a disagreement about a design, and how it ended.Behavioral

Must know

Ranked by how much of the evidence points at each topic.

Spark and big dataReported2 reported questions across 2 rounds
SQLReported2 reported questions across 1 round
Pipeline and system designReported1 reported question across 1 round
Cloud and toolsIn the prioritiesNamed in the prep priorities
Behavioral and communicationIn the prioritiesNamed in the prep priorities

What matters most

Do the first group before the second.

Hard SQL (CoderPad-style)
Do first (3)
Transformations in pandas/PySpark
AWS Glue/Kinesis + governance; Spark optimization + pipeline design
APIs
Then
Content/ad-yield domain metrics
Behavioral

Rejection patterns

Why candidates were turned down, as reported.

Ignoring the governance slice
Weak hard-SQL
SQL is named in 37 of 50 company accounts.
Shaky pandas/PySpark transformations
Spark is named in 25 of 50 company accounts.
No AWS Glue/Kinesis experience
Cloud and tools is named in 4 of 50 company accounts.

Reported experiences

1 reported, 4 composite. Each opens and closes. Composites are labelled.

5 accounts

Data Engineer II (~3 YoE)Date not statedReportedCandidate account
Hard SQL on CoderPad, then a dataset task with five transformations (pandas or PySpark) and three API questions, then a final round on past work, Spark tuning and pipeline design.
What to take from it Practise transforming a dataset in pandas or PySpark under time.
Composite walkthroughs. Built from the company's documented loop, not from one person's account.
The SQL roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: A hard-level SQL question on CoderPad; Window functions, complex joins, optimization.
What to take from it Practise these questions before you reach this round.
Questions named
- A hard-level SQL question on CoderPad
- Window functions, complex joins, optimization
The Transformations / PySpark roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: A dataset with five transformations to write in pandas or PySpark; 3 questions on APIs.
What to take from it Practise these questions before you reach this round.
Questions named
- A dataset with five transformations to write in pandas or PySpark
- 3 questions on APIs
The Final roundDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Questions reported for this round: Past experience, Spark optimization, pipeline design (partly HR).
What to take from it Practise these questions before you reach this round.
Questions named
- Past experience, Spark optimization, pipeline design (partly HR)
The whole loop, start to finishDate not statedComposite
This is a composite, not one person's account. It is built from the loop we have on record for Warner Bros. Discovery. Candidates go through 5 stages, in this order: Phone screen, then Hard SQL (CoderPad), then 5 transformations + API, then Final (experience + Spark + design), then Offer.
What to take from it Know the order, so that no stage surprises you.

Sources and how sure we are

AWS Glue/Kinesis + the governance slice are commonly-overlooked prep areas.

growdataskills — WBD Data Engineer II, 3 YoE
datainterview — Warner Bros. Data Engineer guide (guide, not a first-hand account)

Rehearse the Warner Bros. Discovery loop

Their reported questions, one at a time, against a stopwatch.

SQL · 1 of 5

A hard-level SQL question on CoderPad

Out loud, in order: clarify, build it, check it, explain it.

Practise SQL

00:00

Your preparation plan

Pick your level and the weeks you have.

Built from what Warner Bros. Discovery asks, strongest first. For the wider basics at your level, follow the Mid level plan alongside it.

Week 1
Spark and big data
Read: Spark chapters Drill: Spark playground Say it aloud: Spark questions Full plan: Ace the Spark round
SQL
Read: SQL chapters Drill: SQL practice Say it aloud: SQL questions Full plan: Ace the SQL round
Pipeline and system design
Read: Data pipeline chapters Drill: Pipeline practice Say it aloud: Data pipeline questions Full plan: Ace the pipeline round
Cloud and tools
Read: Data pipeline chapters Say it aloud: AWS questions
Behavioral and communication
Read: Behavioral storytelling Say it aloud: Behavioral questions
Week 2
Rehearse the Warner Bros. Discovery loop
Run the question deckThen repeat your weakest topic once more.

What Warner Bros. Discovery does

The loop

What each round expects

SQL

Transformations / PySpark

Final

Reported interview questions

Reported from accounts and guides, by round

Expected written from Warner Bros. Discovery's standards

Must know

What matters most

Rejection patterns

Reported experiences

Questions named

Questions named

Questions named

Rehearse the Warner Bros. Discovery loop

Your preparation plan

Week 1

Week 2

What Warner Bros. Discovery does

The loop

What each round expects

SQL

Transformations / PySpark

Final

Reported interview questions

Reported from accounts and guides, by round

Expected written from Warner Bros. Discovery's standards

Must know

What matters most

Rejection patterns

Reported experiences

Questions named

Questions named

Questions named

Rehearse the Warner Bros. Discovery loop

Your preparation plan

Week 1

Week 2