Data
LSM Tree
Writes buffer in a memtable and flush as immutable sorted files, merged by background compaction.
Why interviewers ask about it
Sequential writes make it excellent for high ingest; reads must check several files, so Bloom filters are essential. Compaction causes the p99 spikes that page you at 3 a.m.
Related terms
This term is part of the free System Design interview preparation module - browse the full glossary for every definition.