Plan Visualisers: Letting a Tool Point at the Expensive Node
EXPLAIN output in JSON format can be pasted into a visualiser that draws the tree, subtracts child time to show each node's own cost, and highlights the biggest estimate mismatches. Tools like explain.depesz.com, explain.dalibo.com and pganalyze's plan viewer do in a second what the subtraction habit does by hand. They are a convenience, not a substitute: if you cannot read the plan yourself you cannot tell when the highlight is pointing at a symptom rather than a cause. Take care with pasting production SQL into a public site.
Questions this Concept answers
Why do visualisers subtract child time from each node before highlighting anything?
J
jeremy
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