MySQL utf8mb4 Collation Choices and Index Performance
In MySQL, always use utf8mb4 for text, since the older utf8 alias supports only three bytes per character and cannot store all Unicode, including emoji. The...
Category
MySQL
Fixes for connection limits, query performance, and encoding issues in MySQL.
MySQL Online Schema Changes Without Locking Large Tables
Many schema changes on large MySQL tables can run online with InnoDB's native online DDL, using ALGORITHM=INPLACE or INSTANT and an explicit LOCK clause so the...
MySQL Slow Query Log Analysis for Production Tuning
The MySQL slow query log records statements that run longer than a threshold, and analyzing it shows which queries cost the most in total time, not just which...
MySQL Histograms for Skewed Query Optimizer Estimates
Optimizer histograms improve estimates when column values are unevenly distributed. Start with a clearly defined correctness invariant and workload. Identify...
MySQL Foreign Key Cascades vs Application Managed Deletes
Cascading constraints preserve referential behavior in the database while application deletes allow domain workflows. Start with a clearly defined correctness...
MySQL Composite Index Column Order for Filtered and Sorted Queries
In a MySQL composite index, put columns used in equality conditions first, then the column used for sorting or range filtering. The index is usable from its...
MySQL Transaction Isolation Levels Trade Offs for Web Applications
MySQL InnoDB defaults to REPEATABLE READ, which suits most web applications because it gives each transaction a consistent snapshot of the data. READ COMMITTED...
MySQL Read Committed vs Repeatable Read for Order Processing
Transaction isolation changes read visibility and locking interactions under concurrent order updates. Reliable applications must preserve explicit correctness...
MySQL Invisible Indexes for Safer Query Plan Experiments
Invisible indexes permit optimizer experiments without dropping structures that still require storage and maintenance. Reliable applications must preserve...