advanced~3h
Reading Execution Plans Like a Practitioner
How to generate an execution plan and actually read it — cost, row estimates, join order, access paths, and the specific warning signs that separate a healthy plan from a dangerous one.
Learning objectives
- Generate an execution plan using EXPLAIN PLAN and a real execution trace
- Read a plan's indentation to determine operation order and dependency
- Distinguish a full scan, an index scan, and an index seek/unique lookup by their cost profile
- Interpret estimated rows versus actual rows as a diagnostic signal
- Identify at least four concrete warning signs of a troubled plan
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Reading Execution Plans Like a Practitioner