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index usage

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Full-Stack Internet Architecture

Apr 2, 2024 · Databases

Does MySQL’s OR Operator Use Indexes? Experimental Findings and Optimization Tips

The article demonstrates through a practical experiment that MySQL will use indexes for an OR condition only when both operands are indexed, otherwise it falls back to a full table scan, and it suggests using UNION as an optimization when one side lacks an index.

Database PerformanceMySQLOR operator

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Does MySQL’s OR Operator Use Indexes? Experimental Findings and Optimization Tips

Top Architect

Jul 5, 2021 · Databases

MySQL Implicit Type Conversion Leads to Unexpected Query Results

This article explains how MySQL implicitly converts mismatched column types—such as comparing a VARCHAR column with a numeric literal—into floating‑point numbers, causing seemingly equal values to match, losing index usage, and potentially producing incorrect query results.

Floating PointMySQLVARCHAR

0 likes · 7 min read

MySQL Implicit Type Conversion Leads to Unexpected Query Results