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This article examines how InnoDB acquires various row, gap, and next‑key locks during INSERT … ON DUPLICATE KEY UPDATE statements under REPEATABLE‑READ and READ‑COMMITTED isolation levels, illustrating the lock behavior with detailed SQL examples and performance‑schema queries.
This article examines how InnoDB acquires row‑level locks during INSERT … ON DUPLICATE KEY operations under REPEATABLE‑READ and READ‑COMMITTED isolation levels, explains the lock types on primary and unique indexes, and shows the rollback and lock‑conversion process with concrete SQL examples.
This article demonstrates how InnoDB acquires and releases row‑level locks for a sample table under REPEATABLE‑READ and READ‑COMMITTED isolation levels, showing the SQL statements used, the lock types observed in the performance_schema, and the reasons behind the observed locking patterns.
This article demonstrates how InnoDB handles row, next‑key, and gap locks for a SELECT … FOR SHARE query under REPEATABLE‑READ and READ‑COMMITTED isolation levels, showing the preparation steps, SQL examples, lock inspection queries, and a concise summary of the differences.
This article demonstrates how InnoDB acquires different types of row and gap locks under REPEATABLE-READ and READ-COMMITTED isolation levels by creating a test table, inserting data, setting transaction isolation, executing SELECT ... FOR SHARE statements, and inspecting lock information from performance_schema.
This tutorial demonstrates, using MySQL 8.0.32 InnoDB source code, how REPEATABLE-READ and READ-COMMITTED isolation levels affect the locking behavior of SELECT ... FOR SHARE statements on primary‑key rows, including preparation, execution, and detailed lock analysis.
This article investigates whether the REPEATABLE‑READ isolation level in InnoDB fully prevents phantom reads by conducting a series of current‑read and snapshot‑read experiments, analyzing transaction behavior, MVCC mechanisms, and offering recommendations to avoid phantom anomalies.
This article examines whether the REPEATABLE‑READ isolation level in InnoDB fully prevents phantom reads by conducting systematic current‑read and snapshot‑read experiments, analyzing lock mechanisms, MVCC behavior, and presenting detailed SQL scripts, results, and recommendations for avoiding phantom reads.
This article explains why the OBOracle "set transaction read only" command provides repeatable‑read semantics, evaluates the behavior of the JDBC conn.setReadOnly(true) setting, and shows how to achieve true repeatable‑read isolation by enabling the oracleChangeReadOnlyToRepeatableRead option in the OceanBase client.
This article investigates why BenchmarkSQL stalls during MySQL performance testing, tracing the issue to REPEATABLE‑READ isolation causing a dead‑loop in delete‑select transactions, and demonstrates how switching to READ‑COMMITTED resolves the problem through detailed code inspection and experimental verification.
This article explains MySQL's four transaction isolation levels—READ UNCOMMITTED, READ COMMITTED, REPEATABLE READ, and SERIALIZABLE—by creating a simple table, inserting test data, and running step‑by‑step SQL scripts that illustrate the behavior of each level, including phenomena such as dirty reads, non‑repeatable reads, phantom reads, and locking.
This article reproduces a MySQL 8.0.32 InnoDB scenario where inserting a row that violates a unique index causes a next‑key exclusive lock on the primary‑key supremum record, explains the underlying implicit‑lock mechanism, walks through the relevant source‑code stack, and details the lock‑conversion and rollback steps under REPEATABLE‑READ isolation.
This article explains the concept of phantom reads, distinguishes them from non‑repeatable reads, critiques the ANSI SQL isolation‑level definitions, and shows how MySQL implements repeatable‑read using locks and MVCC to prevent both strict and loosely defined phantom anomalies.
This article explains why MySQL chooses Repeatable Read as its default transaction isolation level, contrasting it with Oracle’s default Read Committed, and discusses how binlog formats, GAP locks, and historical bugs influence this design decision.
This article presents a hands‑on experiment that measures the performance impact of using pt‑table‑checksum on a MySQL master‑slave setup, explains the tool’s design choices such as reduced lock‑wait time and RR isolation, and concludes that its effect on production traffic is minimal when configured properly.
This article explains MySQL’s transaction isolation levels, clarifies the differences between dirty reads, non‑repeatable reads and phantom reads, and demonstrates through experiments why the REPEATABLE READ level can prevent phantom reads, while also discussing its limitations, MVCC, and locking mechanisms.