# PostgreSQL GUC Encyclopedia

> Every core PostgreSQL configuration parameter observed from 9.0 through 19 Beta 3, with history, defaults, mechanisms, tuning guidance, and Pigsty context.
---

This is the working index of PostgreSQL configuration parameters—not a marketing
landing page. Start with a parameter, compare major versions, or inspect exactly
where Pigsty diverges from upstream defaults.

| Dataset | Value | What it means |
| --- | --- | --- |
| PostgreSQL scope | `9.0–19 Beta 3` | 17 measured release points; 19 Beta 3 is pre-GA |
| Unique parameters | `447` | Union of every observed `pg_settings.name`, including removed parameters |
| Languages | English · 中文 | English is canonical; translations share routes and heading IDs |
| Evidence | Docker · PostgreSQL docs · Git · Pigsty | Facts retain source version, path, and verification status |
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## Browse {#browse}

- [Parameters](/parameters/) — identity, lifecycle, defaults, mechanism, tuning, pitfalls, and references.
- [Version diffs](/diff/) — added, removed, and default-changing parameters between adjacent majors.
- [Pigsty defaults](/pigsty/) — the OLTP, OLAP, CRIT, and TINY template matrix.
- [Methodology](/methodology/) — evidence labels, lifecycle rules, and terminology.
- [Full JSONL export](/data/guc.jsonl) — one normalized record per parameter.

## Representative dossiers {#representative-dossiers}

- [`shared_buffers`](/parameters/shared-buffers/) — memory units, a real boot-default transition, and a resource-sized Pigsty value.
- [`wal_level`](/parameters/wal-level/) — enum semantics, restart scope, and cross-parameter constraints.
- [`wal_keep_segments`](/parameters/wal-keep-segments/) — a removed parameter and its PG13 replacement.

> [!NOTE]
> **Fact boundary.** Values labelled as facts come from measured `pg_settings`, verified official anchors, Git history, or pinned Pigsty source. Tuning recommendations are explicitly advice; Pigsty rationale remains marked for human review until approved.

> [!WARNING]
> PostgreSQL 19 Beta 3 is a prerelease snapshot. Its parameter set, defaults, and behavior can change before PostgreSQL 19 GA; do not use the beta dossiers as production compatibility guarantees.

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Section pages:

- [Parameters](/parameters/): Complete dossiers for all 447 core PostgreSQL configuration parameters observed from 9.0 through 19 Beta 3.
- [Version diffs](/diff/): GUCs added, removed, or changed in boot default between adjacent PostgreSQL majors.
- [Pigsty defaults](/pigsty/): Complete OLTP, OLAP, CRIT, and TINY template deltas from upstream PostgreSQL boot defaults.
- [Methodology and terminology](/methodology/): Evidence boundaries, lifecycle rules, default-value semantics, Pigsty fixtures, and the bilingual glossary used across the GUC Atlas.