Caching Plans: Prepared Statements and the Generic Plan
Before it runs, every query is parsed and planned, which takes real work.
If you run the same query shape over and over with only the values changing, redoing that each time is wasteful. A prepared statement remembers the parsed and planned form so later runs skip straight to execution.
Pro members see the rest of this lesson
- A 4-step state diagram: Plan → Compare → Switch → Skew
- The full mechanism: what PostgreSQL does internally, in source terms
- 1 SQL query you can run, each labelled by how it was verified
- 2 transcripts captured on PostgreSQL 17.10
- The closing insight, the mistake it prevents, and what it changes in your work
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Check it against the source1 citation in postgres/postgres · file, symbol and line verified on REL_17_STABLE
Primary symbol: GetCachedPlan · line 1176
Anchored to postgres/postgres on REL_17_STABLE and cross-checked against the manual for PostgreSQL 15–18. Every query here was run and its output captured on a throwaway PostgreSQL 17.10 lab; corrections are noted inline. PREPARE / plan caching in the official docs →
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