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pgplex: The Postgres Toolchain for Humans and Agents - pgconsole · pgschema · pgtui · pgparser

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pgparser - Pure Go PostgreSQL Parser

pgparser is a pure Go implementation of the PostgreSQL SQL parser. It translates the original PostgreSQL grammar (gram.y) into Go using goyacc, ensuring 100% compatibility with the PostgreSQL parse tree structure.

Target PostgreSQL Version: 17.7 (REL_17_STABLE)

Features

• 100% Native Go: No CGO, no external dependencies.
• AST Compatibility: The generated Abstract Syntax Tree (AST) strictly matches PostgreSQL's internal Node structures (parsenodes.h), enabling seamless integration with other PG-compatible tools.
• Battle-Tested: Verified against PostgreSQL's own massive regression test suite (~45,000 SQL statements) with a 99.6% pass rate.
• Thread Safe: The parser is designed to be safe for concurrent use.

Installation

go get github.com/pgplex/pgparser

Quick Start

package main

import (
	"encoding/json"
	"fmt"
	"log"

	"github.com/pgplex/pgparser/parser"
)

func main() {
	sql := "SELECT * FROM users WHERE id > 100"

	// Parse the SQL string
	stmts, err := parser.Parse(sql)
	if err != nil {
		log.Fatalf("Parse error: %v", err)
	}

	// Print the AST as JSON
	jsonBytes, _ := json.MarshalIndent(stmts, "", "  ")
	fmt.Println(string(jsonBytes))
}

Architecture

This project is not a hand-written parser. It is a port of the official PostgreSQL source code:

1. Grammar: parser/gram.y is a translated version of PostgreSQL's src/backend/parser/gram.y.
2. Lexer: parser/scan.l logic is reimplemented in Go in parser/lexer.go.
3. Nodes: nodes/ contains Go struct definitions that map 1:1 to PostgreSQL's C structs.

Development

Requirements

• Go 1.18+
• goyacc (installed via go install golang.org/x/tools/cmd/goyacc@latest)

Build & Test

# Regenerate parser (if gram.y changed)
make generate-parser

# Run tests
go test ./...

# Run PostgreSQL regression tests compatibility check
go test ./parser/pgregress -run TestPGRegressStats -v

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