This article explains the concept of MySQL pessimistic locking, its implementation via row‑level locks in InnoDB, and provides step‑by‑step SQL examples showing how SELECT … FOR UPDATE secures data against concurrent modifications.
This article explains the types of InnoDB row‑level locks—record lock, gap lock, and next‑key lock—describes how MySQL determines lock ranges based on indexing, outlines the two fundamental locking principles with associated optimizations, and provides concrete examples for primary‑key and ordinary indexes.
This article explains why an UPDATE on a MySQL row that changes a regular column proceeds without blocking, while an UPDATE that modifies the primary‑key value gets blocked, by analyzing the locks set by preceding transactions, the B+‑tree index structure, and the delete‑plus‑insert rewrite performed by InnoDB.
This article explains MySQL's lock mechanisms—including row‑level, page‑level and table‑level locks, their shared and exclusive modes, the differences between optimistic and pessimistic concurrency control, and practical tips for avoiding deadlocks in InnoDB.
