Database / RocksDB Basics Interview Questions
Define the LSM-Tree (Log-Structured Merge-Tree)?
A Log-Structured Merge-Tree is a data structure designed to make writes fast by turning random writes into sequential ones, at the cost of some added complexity on the read path.
- New writes go into an in-memory structure first, rather than being written directly to their final location on disk
- That in-memory data is periodically flushed to disk as an immutable, sorted file
- A background compaction process merges these files over time to keep the overall structure efficient to read from
This design is what lets RocksDB and similar systems sustain very high write throughput, since sequential writes are dramatically faster than scattered random writes on most storage hardware.
What does an LSM-Tree turn random writes into?
Where do new writes go first in an LSM-Tree?
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