pg_grammar_guard

pg_grammar_guard : Catalog-derived grammars and approved grammar drift checks

Overview

Packages

Source

pig build pkg pg_grammar_guard;		# build rpm/deb

Install

Make sure PGDG and PIGSTY repo available:

pig repo add pgsql -u   # add both repo and update cache

Install this extension with pig:

pig install pg_grammar_guard;		# install via package name, for the active PG version

pig install pg_grammar_guard -v 18;   # install for PG 18
pig install pg_grammar_guard -v 17;   # install for PG 17
pig install pg_grammar_guard -v 16;   # install for PG 16
pig install pg_grammar_guard -v 15;   # install for PG 15
pig install pg_grammar_guard -v 14;   # install for PG 14

Create this extension with:

CREATE EXTENSION pg_grammar_guard CASCADE; -- requires pg_living_assertions

Usage

Sources:

• README.md
• pg_grammar_guard.control
• CHANGELOG.md

pg_grammar_guard 0.4.8 creates GBNF or JSON Schema from catalog identifiers and watches approved grammars for drift. It is pure SQL and requires pg_living_assertions 0.5.9 or later.

Core Workflow

CREATE EXTENSION pg_grammar_guard CASCADE;
CREATE TABLE public.grammar_demo (id integer, label text);
SELECT grammar_guard.grammar_for_json(ARRAY[
  ROW('column', 'enum',
      grammar_guard.catalog_columns('public.grammar_demo'), true)
]::grammar_guard.grammar_field[]);

Operational Boundaries

grammar_guard.catalog_tables() and grammar_guard.catalog_columns() expose catalog names; grammar_guard.grammar_for_json() assembles typed fields, nested structures and bounded arrays. grammar_guard.watch() records the SQL that regenerates a grammar, and grammar_guard.check_grammar() compares it with the approved state in living_assertions.status. The generating query resolves with its author search path and executes as that author. Input NULLs, empty/duplicate field names, empty pivots and invalid bounds are rejected; max_items is capped at 1000. Version 0.4.8 changes canonical fingerprints, and the ordered catalog list can make an existing watch fail once: inspect and re-approve it. A grammar controls allowed tokens, not semantic correctness or authorization. Register trusted SQL only. No preload is required. Current Apache-2.0 licensing begins at 0.4.4; earlier releases retain their original license.