Question 1

How would you monitor and reduce disk-based queries (disk spilling)?

Accepted Answer

Disk spilling occurs when memory is exceeded—often 10–100x slower. WHY: Spilling indicates memory-pressure; it kills SLAs and increases I/O cost. MONITOR: Spark UI (spilled_bytes), Snowflake query_history (bytes_spilled_to_local_storage), Redshift SVL_QUERY_METRICS. REDUCE: (1) Increase executor memory or use memory-optimized instances. (2) Broadcast joins for small tables—tune spark.sql.autoBroadcastJoinThreshold. (3) Repartition before expensive ops to distribute load....

Question 2

Describe handling schema evolution in AWS Redshift without downtime.

Accepted Answer

**Section 1 — The Context (The 'Why')**
This system faces scale and failure challenges at production. A naive approach breaks under load, loses data, or violates compliance. The primary challenge varies by domain: notifications need preference respect; banking needs ACID; pipelines need idempotency....

Question 3

How would you design a data archiving strategy in S3 using lifecycle policies?

Accepted Answer

**Section 1 — The Context (The 'Why')**
The primary challenge in 'How would you design a data archiving strategy in S3 using lifecycle policies?' centers on designing for production scale, correctness guarantees, and operational resilience. A naive or underspecified design fails under load: single points of failure cascade, non-idempotent operations cause duplicates on retry, and lack of observability blocks root-cause analysis....

Question 4

How would you set up end-to-end tracing for a complex pipeline?

Accepted Answer

**Section 1 — The Context (The 'Why')**
The primary challenge in 'How would you set up end-to-end tracing for a complex pipeline?' centers on designing for production scale, correctness guarantees, and operational resilience. A naive or underspecified design fails under load: single points of failure cascade, non-idempotent operations cause duplicates on retry, and lack of observability blocks root-cause analysis....

Capco System Design Interview Questions

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Capco System Design Interview Questions

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