How Much Will This Cost?

Concepts: paCompression, paSparkExecutionModel

Cost isn't a line item - it's an architectural constraint that shapes every decision. The interviewer wants to see you model costs at the per-query and per-team level, not just estimate monthly S3 bills. Per-Query Cost Modeling Every query has a measurable cost. In BigQuery, it's explicit: $6.25 per TB scanned. In Spark, it's compute-seconds × instance cost. In Snowflake, it's credits consumed × credit price. A strong engineer can estimate the cost of any query before it runs and identify the 10 queries that drive 60% of the compute bill. The most expensive query is the one nobody notices. A dashboard that refreshes every 15 minutes with a full table scan costs more per month than the biggest ad-hoc analysis. Finding these silent cost centers requires query-level attribution. Chargeback