How MySQL’s Skip Scan Defies the Leftmost Prefix Rule

This article explains MySQL’s composite index leftmost‑prefix rule, demonstrates how the Skip Scan Range Access Method introduced in MySQL 8.0.13 can use indexes without following the rule, provides step‑by‑step examples, code snippets, and discusses its implementation, benefits, and limitations.

Composite IndexDatabase OptimizationSkip Scan

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How MySQL’s Skip Scan Defies the Leftmost Prefix Rule

Aikesheng Open Source Community

Apr 2, 2021 · Databases

Why MySQL Chooses a Composite Index Even When the Query Skips the Leftmost Column

This article explains why MySQL may still use a composite index as a covering or range index despite the query not following the leftmost‑prefix rule, by analyzing optimizer trace output and demonstrating the behavior with concrete experiments.

Composite IndexOptimizer_traceSkip Scan

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Why MySQL Chooses a Composite Index Even When the Query Skips the Leftmost Column

Aikesheng Open Source Community

Apr 23, 2019 · Databases

Key Improvements in MySQL 8.0.13 and 8.0.14

This article reviews the most notable enhancements introduced in MySQL 8.0.13 and 8.0.14, covering query speed optimizations, the new Skip Scan access method, changes to index design rules, deprecated features, and several operational and security improvements for database administrators and developers.

8.0.138.0.14Skip Scan

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Key Improvements in MySQL 8.0.13 and 8.0.14