Performance Engineering and Cost Optimization Questions

Engineering practices and trade offs for meeting performance objectives while controlling operational cost. Topics include setting latency and throughput targets and latency budgets; benchmarking profiling and tuning across application database and infrastructure layers; memory compute serialization and batching optimizations; asynchronous processing and workload shaping; capacity estimation and right sizing for compute and storage to reduce cost; understanding cost drivers in cloud environments including network egress and storage tiering; trade offs between real time and batch processing; and monitoring to detect and prevent performance regressions. Candidates should describe measurement driven approaches to optimization and be able to justify trade offs between cost complexity and user experience.

EasyTechnical

77 practiced

How do approximation algorithms (HyperLogLog, Count-Min Sketch) trade accuracy for performance and cost in BI metrics? Give an example where approximate counts are acceptable and another where exact counts are required. Explain how to communicate these trade-offs to stakeholders.

MediumTechnical

59 practiced

A critical dashboard query involves a heavy group-by on a high-cardinality column. Propose approaches to accelerate this query: approximate top-k, pre-aggregations, bloom filters, or sharded aggregation. For each, explain complexity, accuracy impacts, and expected resource savings.

MediumTechnical

52 practiced

A Tableau dashboard connected via a live Redshift query becomes significantly slower after adding a new visualization that joins to a large reference table. Walk through step-by-step how you would debug the slowdown from the dashboard front-end down to the database. What specific tools, metrics, and quick mitigations would you try during the investigation?

MediumTechnical

53 practiced

Create a prioritized checklist for making a large, interactive executive dashboard faster: include frontend changes, query-level optimizations, caching, and governance items to control future regressions. Provide expected effort vs impact for each checklist item.

MediumTechnical

45 practiced

You observe that query costs for a set of ad-hoc reports spike each month-end. Provide a prioritized troubleshooting checklist and immediate mitigation actions (both short-term and medium-term) to reduce cost and restore stable performance.

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