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Home/Questions/General/Other/Given exchange rates for USD to INR with timestamps: Find the ticket price in rupees for various dates. Use the latest exchange rate based on the timestamp for each date.

Given exchange rates for USD to INR with timestamps: Find the ticket price in rupees for various dates. Use the latest exchange rate based on the timestamp for each date.

General/Othermedium0.2 min readPremium

**Approach**: Time-based join—for each ticket_date, get max rate_timestamp <= ticket_date. CROSS APPLY / LATERAL with ORDER BY rate_timestamp DESC LIMIT 1. Spark: asof join (merge_asof in Pandas); or join with condition + window for latest....

🤖 Analyze Your Answer
Frequency
Low
Asked at 1 company
Category
243
questions in General/Other
Difficulty Split
151E|43M|49H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Expedia
Key Concepts Tested
joinsparkwindow

Why This Question Matters

This medium-level General/Other question appears frequently in data engineering interviews at companies like Expedia. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (join, spark, window) will help you answer variations of this question confidently.

How to Approach This

Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.

Expert Answer
43 words

Approach: Time-based join—for each ticket_date, get max rate_timestamp <= ticket_date. CROSS APPLY / LATERAL with ORDER BY rate_timestamp DESC LIMIT 1. Spark: asof join (merge_asof in Pandas); or join with condition + window for latest. Key: 'latest' = max timestamp <= ticket date.

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