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In MySQL 5.7, using REPLACE INTO on a table that has an auto‑increment primary key and an extra unique index can cause the master and slave AUTO_INCREMENT counters to diverge, leading to duplicate‑key errors after failover, a bug mitigated by upgrading to MySQL 8.0, manual counter fixes, or avoiding REPLACE INTO.
The article demonstrates via example how REPLACE INTO can cause data inconsistency and auto‑increment anomalies in master‑slave MySQL setups, explains the underlying binlog behavior, highlights risk points, and advises against using REPLACE when business logic depends on auto‑increment IDs.
This article explains several MySQL techniques—INSERT IGNORE, ON DUPLICATE KEY UPDATE, and REPLACE INTO—to efficiently insert large volumes of data while preventing duplicate primary‑key or unique‑key rows, and provides practical code examples for single and batch operations.
This article explains how MySQL UNIQUE indexes affect data insertion and auto‑increment behavior, compares them with primary keys, and presents three techniques—INSERT IGNORE, REPLACE INTO, and INSERT … ON DUPLICATE KEY UPDATE—to prevent duplicate‑key failures, including deadlock considerations.
This article examines why MySQL auto‑increment primary keys can jump unexpectedly when using REPLACE INTO or INSERT … ON DUPLICATE KEY UPDATE, explains the role of innodb_autoinc_lock_mode, demonstrates examples, and offers practical solutions to prevent uncontrolled ID growth.
The article analyzes how MySQL’s REPLACE INTO statement can cause deadlocks by acquiring exclusive GAP locks during duplicate‑key handling, illustrates the issue with a step‑by‑step case study of three concurrent transactions, and recommends using pre‑check SELECT‑INSERT or serializing the statements to avoid the problem.