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Home/Questions/SQL/How do you get new records from a table/file without a modified column? Discuss approaches like hashing or row comparison.

How do you get new records from a table/file without a modified column? Discuss approaches like hashing or row comparison.

SQLeasy0.3 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
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130E|271M|86H
in this category
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1,863
across 7 categories
Asked at these companies
Fractal
Expert AnswerPremium
60 wordsInterview-ready
**Hash-based**: Compute MD5/SHA256 of concat(col1, col2, ...); compare to stored hash per key. New/changed = different hash. **Full comparison**: Diff all columns; expensive for wide tables. **Checksum**: Per-row checksum. **State table**: Store last hash or last record per key; incremental run processes only changed. **Merkle tree**: For very large sets—hierarchical hash....
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