Section

17 pages

Query Performance

EXPLAIN-driven posts on why MySQL and PostgreSQL queries are slow: indexes, selectivity, non-SARGable predicates, covering indexes, sorts, and CPU.

A 10 Gb Database Filled a 200 Gb Disk and Du Could Not Find the Space 0 A Billion Row Versions From One Uncommitted Read Stalled a Mysql Replica 0 A Query on a 3 Billion Row Table Took 100 Minutes: One Added Line Made It 40ms 0 Clustered vs Non Clustered Index: The Table Is the Index in Mysql 0 Collation Drift: The Silent Index Killer 0 Database Deadlocks, Part 1: The Patterns 0 Database Deadlocks, Part 2: Diagnosis, Retries, and Prevention 0 How to Read Explain Analyze: Mysql 0 How to Read Explain Analyze: Postgresql 0 It's Almost Always the Queries, Part I: Why Metal Doesn't Help 0 It's Almost Always the Queries, Part Ii: Troubleshooting Steps 0 It's Almost Always the Queries, Part Iii: When the Cpu Is Pegged 0 It's Almost Always the Queries, Part Iv: When the Sort Spills 0 It's Almost Always the Queries, Part V: Disk Has Two Alarms, Not One 0 Non Sargable Predicates: How a Function in Where Kills Your Index 0 One Column Added to a Select: 1,020 Page Reads Became 166,667 0 Uniqueness and Selectivity: The Two Numbers That Drive Query Plans 0