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Finance, Payments & Fintech

Paytm

Payments / fintech (India) · Data Engineering interview

Deep Spark internals and cluster sizing, scenario SQL (self-joins, window-with-range), and classic coding problems.

Cloud / platform

Spark, Hadoop, Hive, Airflow, Scala

Reported difficulty

Not reported

SQLPythonSparkHadoopHiveAirflow

Hiring process

OA (Python/SQL/DSA)

Technical (Spark/big data)

Behavioral

Final/managerial

Offer

Round-by-round breakdown

SQL

High confidence

Remove duplicates from a table
IPL team match combinations with conditions (self joins)
Window functions with a RANGE
Design bank statements from a customer table (debit/credit)

Spark

· centralHigh confidence

Join optimization in Spark and Hive
SCD and its types; file formats and compression
A Spark job that took 5 min now takes 2 hours — why?
repartition vs coalesce
How many executors to process 500 GB on a 64 GB RAM / 16-core cluster, and each executor's config?

Coding

Medium confidence

Frequency of each word in a string
Subarray sum equal to K
Merge K sorted lists

System & pipeline design prompts

Payments pipeline (Spark): ingestion → processing → serving; dedup/idempotency

Prep — high priority

Spark internals + cluster sizing (executors/cores/memory for 500GB), join optimization, SCD, file formats, perf debugging
Scenario SQL (dedup, self-joins, window-with-range, statement design)
Coding (subarray sum K, merge K sorted lists)

Prep — medium priority

Hadoop/Hive/Airflow/Scala
Payments pipeline design
Behavioral

Rejection patterns

Cannot reason about Spark performance degradation or cluster sizing
Weak join optimization/SCD
Shaky scenario SQL

Reported experiences

Data Engineer (~2 YoE)

ReportedFirst-hand

OA → technical (SQL: dedup, IPL self-join, window-with-range, bank-statement design; Spark: join optimization, SCD types, file formats, 5min→2hr perf debug, repartition vs coalesce, cluster sizing 500GB; coding: word freq, subarray sum K, merge K sorted lists) → behavioral.

Rehearse for Paytm

Answered questions on what Paytm actually asks — each with the short answer, the answer that gets you rejected, and the follow-up.

Then build one and have it reviewed: design a daily orders pipeline or model a marketplace. No account.

All interview experiences