Database / RocksDB Basics Interview Questions
Define Universal Compaction?
Universal compaction, sometimes called tiered compaction, keeps SSTables organized by age rather than by strict, non-overlapping key ranges across levels.
- New SSTables are added to a sorted run, and periodically a group of runs gets merged together into a larger one
- Tends to produce lower write amplification than leveled compaction, since data is rewritten less often
- Trades that write efficiency for higher space amplification and potentially more SSTables to check on a read
This style is often chosen for extremely write-heavy workloads where minimizing the total amount of data rewritten matters more than optimal read performance.
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