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What is the salting technique, and when would you use it?

Spark/Big Datahard0.4 min readPremium
Frequency
Low
Asked at 1 company
Category
452
questions in Spark/Big Data
Difficulty Split
88E|81M|283H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
American Express
Key Concepts Tested
joinpartition
Expert AnswerPremium
82 wordsInterview-ready
**Salting**: Add random suffix to skewed keys. key → key_1, key_2, ... key_N. Distributes load across partitions. **When**: One/few keys dominate (e.g., null, default, popular tenant). Causes stragglers. **Steps**: Salt key → shuffle (now distributed) → aggregate/join → merge salted groups. **Why**: Eliminates straggler; job finishes. Without salt, one task runs 10x longer. **Trade-offs**: Extra shuffle and merge. Salt cardinality = tune....
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