effect-sql-googlesql

GoogleSQL compiler for @effect/sql with Cloud Spanner support.

Features

• 🎯 Type-safe GoogleSQL query compilation
• ☁️ Cloud Spanner type hints for parameters
• 🔒 Proper escaping with backticks
• ⚡ Built for production use with Effect.ts

Installation

pnpm add effect-sql-googlesql @effect/sql effect

Usage

This package is typically consumed via effect-sql-spanner, not used directly. It provides the GoogleSQL compiler that translates Effect SQL statements to Spanner-compatible GoogleSQL.

Type Hints for Spanner Parameters

GoogleSQL/Spanner requires explicit type hints for parameters in some contexts:

import * as Compiler from "effect-sql-googlesql/Compiler"
import * as Statement from "@effect/sql/Statement"

// Use paramOf for typed parameters
const jsonData = { user: "alice", role: "admin" }
const fragment = Compiler.paramOf(Compiler.types.json(), jsonData)

// Available types:
Compiler.types.string()
Compiler.types.int64()
Compiler.types.float64()
Compiler.types.bool()
Compiler.types.json()
Compiler.types.bytes()
Compiler.types.timestamp()
Compiler.types.date()
Compiler.types.array(Compiler.types.string())  // Array types

Creating a Compiler

import { makeCompiler } from "effect-sql-googlesql/Compiler"

const compiler = makeCompiler({
  // Optional: transform column names (e.g. camelCase → snake_case)
  transformQueryNames: (name) => name
})

// Compile statements manually (rare - usually handled by @effect/sql)
const statement = Statement.make`SELECT * FROM users WHERE id = ${userId}`
const [sql, params] = compiler.compile(statement)

Using as Effect Layer

import * as Layer from "effect-sql-googlesql/Layer"
import * as Sql from "@effect/sql"
import * as Effect from "effect/Effect"

// Provide compiler via layer
const GoogleSqlCompilerLayer = Layer.layer({
  transformQueryNames: (name) => name
})

const program = Effect.gen(function* () {
  const sql = yield* Sql.client.Client

  // Compiler is used automatically by @effect/sql
  const users = yield* sql`SELECT * FROM users WHERE active = ${true}`

  return users
})

Null Values with Type Hints

import { nullOf, types } from "effect-sql-googlesql/Compiler"

// Create typed null values
const fragment = Statement.make`INSERT INTO users (data) VALUES (${nullOf(types.json())})`

API Reference

makeCompiler(options?)

Creates a GoogleSQL compiler instance.

Parameters:

• options.transformQueryNames?: (value: string) => string - Optional transformer for identifiers

Returns: Statement.Compiler

paramOf(type, value)

Creates a typed parameter for GoogleSQL with explicit Spanner type hints.

Parameters:

• type - Spanner type from types object or string type code
• value - The parameter value

Returns: Statement.Fragment

nullOf(type)

Creates a typed null parameter.

Parameters:

• type - Spanner type from types object or string type code

Returns: Statement.Fragment

types

Spanner data type constructors:

types.string()     // STRING
types.int64()      // INT64
types.float64()    // FLOAT64
types.bool()       // BOOL
types.json()       // JSON
types.bytes()      // BYTES
types.timestamp()  // TIMESTAMP
types.date()       // DATE
types.array(elementType)  // ARRAY<T>

layer(options?)

Creates an Effect Layer that provides the GoogleSQL compiler.

Parameters:

• options - Same as makeCompiler()

Returns: Layer.Layer<never, never, typeof GoogleSqlCompiler>

compiler

Default compiler instance (no name transformation).

Type: Statement.Compiler

How It Works

1. Takes Effect SQL statements (using @effect/sql/Statement)
2. Compiles to GoogleSQL dialect:
   • Escapes identifiers with backticks: `table_name`
   • Converts placeholders to @param1, @param2, etc.
   • Handles RETURNING → THEN RETURN conversion
3. Attaches Spanner type hints as metadata on parameters
4. Returns [sql: string, params: Primitive[]] tuple
5. Type metadata retrieved via getParamTypeMetadata(params)

GoogleSQL vs PostgreSQL

Key differences handled by this compiler:

Feature	PostgreSQL	GoogleSQL
Identifier escaping	"identifier"	`identifier`
Parameter placeholders	$1, $2	@param1, @param2
RETURNING clause	RETURNING	THEN RETURN
Type hints	Optional	Required in some contexts
Array syntax	ARRAY[1,2,3]	[1,2,3]

Production Usage

This package is designed to be consumed via effect-sql-spanner, which provides a complete Spanner client with automatic GoogleSQL compilation:

import * as SpannerClient from "effect-sql-spanner/Client"
import * as Effect from "effect/Effect"

const program = Effect.gen(function* () {
  const sql = yield* SpannerClient.ClientTag

  // GoogleSQL compilation happens automatically
  const users = yield* sql`SELECT * FROM users`

  return users
})

License

Apache-2.0

Author

Ryan Hunter (@artimath)

Links

• @effect/sql Documentation
• Cloud Spanner GoogleSQL Reference
• Effect.ts Documentation