Database Documentation Generator
Overview
Generate comprehensive database documentation by introspecting live PostgreSQL or MySQL schemas, extracting table structures, column descriptions, relationships, indexes, constraints, stored procedures, and views. Produces human-readable documentation in Markdown format including entity-relationship descriptions, data dictionary, and column-level metadata.
Prerequisites
- Database credentials with read access to
information_schema, pg_catalog (PostgreSQL), or system tables (MySQL)
psql or mysql CLI for executing introspection queries- Target output directory for generated documentation files
- Existing column comments (
COMMENT ON COLUMN) enhance output quality significantly
- Knowledge of the business domain for meaningful table/column descriptions
Instructions
- Extract the complete table inventory:
SELECT table_name, obj_description((table_schema || '.' || table_name)::regclass) AS table_comment FROM information_schema.tables WHERE table_schema = 'public' AND table_type = 'BASE TABLE' ORDER BY table_name (PostgreSQL). For MySQL: SELECT TABLE_NAME, TABLE_COMMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE().
- For each table, extract column details:
SELECT c.column_name, c.data_type, c.character_maximum_length, c.is_nullable, c.column_default, pgd.description AS column_comment FROM information_schema.columns c LEFT JOIN pg_catalog.pg_description pgd ON pgd.objsubid = c.ordinal_position AND pgd.objoid = (c.table_schema || '.' || c.table_name)::regclass WHERE c.table_name = 'target_table' ORDER BY c.ordinal_position.
- Extract primary key and unique constraint definitions:
SELECT tc.constraint_name, tc.constraint_type, kcu.column_name FROM information_schema.table_constraints tc JOIN information_schema.key_column_usage kcu ON tc.constraint_name = kcu.constraint_name WHERE tc.table_name = 'target_table' AND tc.constraint_type IN ('PRIMARY KEY', 'UNIQUE').
- Extract foreign key relationships to build the relationship map:
SELECT tc.table_name AS child_table, kcu.column_name AS child_column, ccu.table_name AS parent_table, ccu.column_name AS parent_column, rc.delete_rule, rc.update_rule FROM information_schema.table_constraints tc JOIN information_schema.key_column_usage kcu ON tc.constraint_name = kcu.constraint_name JOIN information_schema.referential_constraints rc ON tc.constraint_name = rc.constraint_name JOIN information_schema.constraint_column_usage ccu ON rc.unique_constraint_name = ccu.constraint_name WHERE tc.constraint_type = 'FOREIGN KEY'.
- Extract index definitions:
SELECT indexname, indexdef FROM pg_index