Big Data Technology Tribe

Apr 21, 2026 · Databases

How Lance Implements Merge‑Insert: Upserts, Deletes, and Deduplication Explained

This article explains the merge‑insert operation in Lance, detailing its SQL‑like semantics, typical use‑cases such as bulk upserts and conditional deletes, the underlying DataFusion planning and execution flow, the generation of the __action column, and the handling of source‑side duplicate rows.