PostgreSQL Syntax Reference

PostgreSQL Syntax Reference

Use this skill when you need to understand PostgreSQL's SQL syntax, DDL statement structure, or how PostgreSQL parses specific SQL constructs. This is essential for correctly parsing SQL files and generating valid DDL in pgschema.

When to Use This Skill

Invoke this skill when:

• Implementing new SQL statement parsing in ir/parser.go
• Debugging SQL parsing issues with pg_query_go
• Understanding complex SQL syntax (CREATE TABLE, CREATE TRIGGER, etc.)
• Generating DDL statements in internal/diff/*.go
• Validating SQL statement structure
• Understanding precedence and grammar rules
• Learning about PostgreSQL-specific syntax extensions

Source Code Locations

Main parser directory: https://github.com/postgres/postgres/blob/master/src/backend/parser/

Key files to reference:

Grammar and Lexer

• gram.y - Main grammar file - Yacc/Bison grammar defining PostgreSQL SQL syntax
• scan.l - Lexical scanner (Flex/Lex) - tokenization rules
• keywords.c - Reserved and non-reserved keywords

Parser Implementation

• parse_clause.c - Parsing of clauses (WHERE, GROUP BY, ORDER BY, etc.)
• parse_expr.c - Expression parsing (operators, function calls, etc.)
• parse_type.c - Type name parsing and resolution
• parse_relation.c - Table and relation parsing
• parse_target.c - Target list parsing (SELECT list, etc.)
• parse_func.c - Function call parsing
• parse_utilcmd.c - Utility commands (DDL statements like CREATE, ALTER, DROP)

Analysis and Transformation

• analyze.c - Post-parse analysis
• parse_node.c - Parse node creation utilities

Step-by-Step Workflow