@jr200/xstate-duckdb

A state machine for managing DuckDB operations in web applications. This library provides a type-safe interface for database initialization, query execution, transaction management, and table catalog operations.

Features

• State Management: Full XState integration for predictable database state management
• DuckDB Integration: Built on top of @duckdb/duckdb-wasm for browser-based analytics
• Transaction Support: Complete transaction lifecycle management (begin, execute, commit, rollback)
• Table Catalog: Dynamic table loading, versioning, and management
• Type Safety: Full TypeScript support with comprehensive type definitions
• Multiple Data Formats: Support for Arrow IPC and JSON data formats
• Compression: Built-in support for data compression (zlib)
• Real-time Updates: Subscription-based table change notifications

Installation

npm install @jr200/xstate-duckdb
# or
yarn add @jr200/xstate-duckdb
# or
pnpm add @jr200/xstate-duckdb

API Reference

Machine States

The duckdbMachine has the following states:

• idle: Initial state, waiting for configuration
• configured: Database configured, ready to connect
• initializing: Database initialization in progress
• connected: Database connected and ready for operations
• disconnected: Database disconnected
• error: Error state

Events

Configuration Events

• CONFIGURE: Configure database parameters and catalog
• RESET: Reset to initial state

Connection Events

• CONNECT: Initialize and connect to database
• DISCONNECT: Disconnect from database

Query Events

• QUERY.EXECUTE: Execute a one-shot query with auto-commit

Transaction Events

• TRANSACTION.BEGIN: Start a new transaction
• TRANSACTION.EXECUTE: Execute a query within a transaction
• TRANSACTION.COMMIT: Commit the current transaction
• TRANSACTION.ROLLBACK: Rollback the current transaction

Catalog Events

• CATALOG.SUBSCRIBE: Subscribe to table changes with a subscription object
• CATALOG.UNSUBSCRIBE: Unsubscribe from table changes using subscription ID
• CATALOG.LIST_TABLES: List all loaded tables
• CATALOG.LOAD_TABLE: Load data into a table
• CATALOG.DROP_TABLE: Drop a table
• CATALOG.LIST_DEFINITIONS: Get catalog configuration

Examples

Basic Usage

import { duckdbMachine } from '@jr200/xstate-duckdb'
import { useActor } from '@xstate/react'

function DatabaseComponent() {
  const [state, send] = useActor(duckdbMachine)

  const initializeDB = () => {
    send({
      type: 'CONFIGURE',
      dbInitParams: {
        logLevel: LogLevel.INFO,
        config: {},
      },
      catalogConfig: {},
    })
    send({ type: 'CONNECT' })
  }

  const runQuery = () => {
    send({
      type: 'QUERY.EXECUTE',
      queryParams: {
        sql: 'SELECT 1 as test',
        callback: (result) => console.log(result),
        description: 'test_query',
        resultType: 'json',
      },
    })
  }

  return (
    <div>
      <button onClick={initializeDB}>Initialize DB</button>
      <button onClick={runQuery}>Run Query</button>
    </div>
  )
}

Transaction Management

const handleTransaction = () => {
  // Begin transaction
  send({ type: 'TRANSACTION.BEGIN' })

  // Execute queries within transaction
  send({
    type: 'TRANSACTION.EXECUTE',
    queryParams: {
      sql: 'INSERT INTO users (name) VALUES ("John")',
      callback: (result) => console.log('Insert result:', result),
      description: 'insert_user',
      resultType: 'json',
    },
  })

  // Commit or rollback
  send({ type: 'TRANSACTION.COMMIT' })
  // or send({ type: 'TRANSACTION.ROLLBACK' })
}

Table Management

const handleTableOperations = () => {
  // Load a table with Arrow data
  send({
    type: 'CATALOG.LOAD_TABLE',
    tableName: 'my_table',
    tablePayload: arrowDataBase64,
    payloadType: 'b64ipc',
    payloadCompression: 'zlib',
    callback: (tableInstanceName, error) => {
      if (error) console.error('Load error:', error)
      else console.log('Table loaded:', tableInstanceName)
    },
  })

  // List all tables
  send({
    type: 'CATALOG.LIST_TABLES',
    callback: (tables) => console.log('Tables:', tables),
  })

  // Subscribe to table changes with enhanced subscription object
  send({
    type: 'CATALOG.SUBSCRIBE',
    subscription: {
      tableSpecName: 'my_table',
      onSubscribe: (id: string, tableSpecName: string) => {
        console.log(`Subscribed to ${tableSpecName} with ID: ${id}`)
      },
      onChange: (tableInstanceName: string, tableVersionId: number) => {
        console.log(`Table updated: ${tableInstanceName}, version: ${tableVersionId}`)
      },
    },
  })

  // Unsubscribe using the subscription ID
  send({
    type: 'CATALOG.UNSUBSCRIBE',
    id: 'subscription_id_here',
  })
}

Subscription Management

The subscription system provides real-time notifications when tables are updated:

// Create a subscription with custom callbacks
const subscription = {
  tableSpecName: 'users',
  onSubscribe: (id: string, tableSpecName: string) => {
    console.log(`Successfully subscribed to ${tableSpecName} with ID: ${id}`)
    // Store the subscription ID for later unsubscription
    setSubscriptionId(id)
  },
  onChange: (tableInstanceName: string, tableVersionId: number) => {
    console.log(`Table ${tableSpecName} updated to version ${tableVersionId}`)
    // Handle table updates - e.g., refresh UI, fetch new data
    refreshTableData(tableInstanceName)
  },
}

send({
  type: 'CATALOG.SUBSCRIBE',
  subscription,
})

// Later, unsubscribe using the stored ID
send({
  type: 'CATALOG.UNSUBSCRIBE',
  id: subscriptionId,
})

Development

Prerequisites

• Node.js 18+
• pnpm (recommended)

Setup

# Install dependencies
pnpm install

# Build the project
pnpm build

# Run tests
pnpm test

# Start development mode
pnpm dev

Running Examples

The project includes a React example in examples/react-test/:

cd examples/react-test
pnpm install
pnpm dev

This will start a development server with a comprehensive UI for testing all database operations.

Contributing

Contributions welcome!

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Add tests if applicable
5. Submit a pull request

License

MIT License - see LICENSE file for details.