MySQL

Quick Reference

Character Set Traps

• utf8 is broken—only 3 bytes, can't store emoji; always use utf8mb4
• utf8mb4_unicode_ci for case-insensitive sorting; utf8mb4_bin for exact byte comparison
• Collation mismatch in JOINs kills performance—ensure consistent collation across tables
• Connection charset must match: SET NAMES utf8mb4 or connection string parameter
• Index on utf8mb4 column larger—may hit index size limits; consider prefix index

Index Differences from PostgreSQL