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README ¶

doubleclick

A ClickHouse SQL parser written in Go. Parses ClickHouse SQL syntax into an Abstract Syntax Tree (AST) and generates EXPLAIN output matching ClickHouse's format.

Installation

go get github.com/sqlc-dev/doubleclick

Usage

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"

	"github.com/sqlc-dev/doubleclick/parser"
)

func main() {
	sql := `SELECT id, name FROM users WHERE active = 1 ORDER BY created_at DESC LIMIT 10`

	stmts, err := parser.Parse(context.Background(), strings.NewReader(sql))
	if err != nil {
		panic(err)
	}

	// Serialize to JSON
	jsonBytes, _ := json.MarshalIndent(stmts[0], "", "  ")
	fmt.Println(string(jsonBytes))

	// Or print EXPLAIN AST output (matches ClickHouse format)
	fmt.Println(parser.Explain(stmts[0]))
}

JSON output:

{
  "selects": [
    {
      "columns": [
        { "parts": ["id"] },
        { "parts": ["name"] }
      ],
      "from": {
        "tables": [
          { "table": { "table": { "table": "users" } } }
        ]
      },
      "where": {
        "left": { "parts": ["active"] },
        "op": "=",
        "right": { "type": "Integer", "value": 1 }
      },
      "order_by": [
        {
          "expression": { "parts": ["created_at"] },
          "descending": true
        }
      ],
      "limit": { "type": "Integer", "value": 10 }
    }
  ]
}

EXPLAIN output:

SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 2)
    Identifier id
    Identifier name
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier (children 1)
       Identifier users
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier active
     Literal UInt64_1
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier created_at
   Literal UInt64_10

Features

Parses SELECT, INSERT, CREATE, DROP, ALTER, and other ClickHouse statements
Handles ClickHouse-specific syntax (Array types, PREWHERE, SAMPLE, etc.)
Supports JOINs, subqueries, CTEs, window functions, and complex expressions
Generates JSON-serializable AST nodes
Produces EXPLAIN AST output matching ClickHouse's format

Directories ¶

Path	Synopsis
ast Package ast defines the abstract syntax tree for ClickHouse SQL.	Package ast defines the abstract syntax tree for ClickHouse SQL.
cmd
next-test command
regenerate-explain command
internal
explain Package explain provides EXPLAIN AST output functionality for ClickHouse SQL.	Package explain provides EXPLAIN AST output functionality for ClickHouse SQL.
lexer Package lexer implements a lexer for ClickHouse SQL.	Package lexer implements a lexer for ClickHouse SQL.
parser Package parser implements a parser for ClickHouse SQL.	Package parser implements a parser for ClickHouse SQL.
token Package token defines constants representing the lexical tokens of ClickHouse SQL.	Package token defines constants representing the lexical tokens of ClickHouse SQL.

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