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What happens if the vacuum command is not run periodically?

Spark/Big Dataeasy0.4 min readPremium

**Without VACUUM**: (1) Old files accumulate—storage grows unbounded. (2) Time travel retains references; VACUUM removes files older than retention (default 7 days). (3) Many small files = slow metadata and reads. (4) File count limits in some systems. **Why Run It**: Reclaim...

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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
PWC

Why This Question Matters

This easy-level Spark/Big Data question appears frequently in data engineering interviews at companies like PWC. While less common, it tests deeper understanding that distinguishes strong candidates.

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Expert Answer
88 words

Without VACUUM: (1) Old files accumulate—storage grows unbounded. (2) Time travel retains references; VACUUM removes files older than retention (default 7 days). (3) Many small files = slow metadata and reads. (4) File count limits in some systems.

Why Run It: Reclaim storage; improve read performance; control file count.

Trade-off: VACUUM removes time-travel capability for older versions. Ensure no active time-travel queries. Set retention based on audit needs.

Scalability Trade-offs: VACUUM on huge tables is expensive; run during maintenance.

Cost Implications: Un-vacuumed = 2–5x storage cost. Schedule weekly.

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