Partitioning: How Declarative Partitioning Prunes Work
Partitioning slices one big table into many smaller child tables by a key like date.
The payoff isn't automatic speed, it's the ability to ignore the slices a query doesn't need, to drop last year's data by discarding a whole slice instead of a slow DELETE, and to maintain each slice on its own.
Pro members see the rest of this lesson
- A 4-step state diagram: All → Plan-time → Run-time → Retire
- The full mechanism: what PostgreSQL does internally, in source terms
- 2 SQL queries you can run, each labelled by how it was verified
- 1 transcript 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: make_partitionedrel_pruneinfo · line 438
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. §5.11 Table Partitioning in the official docs →
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