Copy-on-Write

Copy‑on‑write B‑trees let databases take point‑in‑time snapshots instantly, without blocking writes. This post explains the mechanics, trade‑offs, and real‑world implementations.

Copy‑on‑write avoids costly memory allocation by sharing data until a write occurs, dramatically improving throughput in many systems.

Copy-on-Write B‑Trees provide immutable snapshots for readers while writers work on new nodes, enabling high concurrency with minimal blocking.

Copy‑on‑write lets the kernel clone a process without copying its memory pages, deferring duplication until a write occurs, which dramatically speeds up fork.

This article explains how copy‑on‑write B‑trees work, why they speed up database snapshots, and what trade‑offs developers should consider.