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In Python, process a large CSV in chunks and remove duplicate records based on email and timestamp.

SQLhard0.5 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Amazon
Key Concepts Tested
python
Expert AnswerPremium
109 wordsInterview-ready
Process large CSV in chunks with pandas: import pandas as pd; chunks = pd.read_csv('large.csv', chunksize=10000); seen = set(); results = []; [results.append(chunk.drop_duplicates(subset=['email','timestamp'], keep='last')) for chunk in chunks if not (chunk[['email','timestamp']].apply(tuple, axis=1).isin(seen).all())] — but cross-chunk duplicates remain....
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