Bun Database Integration: AI-Optimized Technical Reference

Configuration

Built-in Database Drivers

Problem Solved: Node.js database packages break on version updates

• Node.js Reality: Requires 4+ packages for PostgreSQL (pg, @types/pg, pg-pool, pg-format)
• Failure Mode: node-gyp compilation errors when Node.js updates (3+ hours debugging time)
• Bun Solution: Built-in drivers since v1.2.21, no external dependencies

Performance Impact: API responses improved from ~300ms to ~120ms in typical setups

Database Connection Syntax

import { sql } from 'bun';

// PostgreSQL
const postgres = sql`postgres://user:pass@localhost/db`;

// MySQL
const mysql = sql`mysql://user:pass@localhost/db`;

// SQLite
const sqlite = sql`sqlite:///path/to/database.db`;

// Production setup with explicit limits
const db = sql`postgres://user:pass@localhost/db?max_connections=20&idle_timeout=30`;

SQLite Compilation Hell Solution

Node.js Problems:

• better-sqlite3 breaks on every Node.js update
• M1 Mac rebuilding takes 5+ minutes
• Alpine Linux Docker builds consistently fail with gyp ERR! build error

Bun Solution:

import { Database } from 'bun:sqlite';

const db = new Database('app.db'); // Creates file if missing
const getUser = db.query('SELECT * FROM users WHERE id = ?');
const user = getUser.get(123);

Resource Requirements

ORM Comparison

ORM	Performance	Setup Difficulty	Breaking Issues
Drizzle	Fast (barely slower than raw SQL)	Clean	Schema design errors
Prisma	Slow but acceptable	Annoying (requires Node.js for codegen)	Code generation failures
TypeORM	Slow everywhere	High pain	Everything

Recommended: Drizzle for new projects, Prisma migration possible but requires dual runtime

Migration Effort Assessment

Time Investment: ~2 hours for medium-sized API
Process:

1. Replace import pg from 'pg' with import { sql } from 'bun'
2. Convert parameterized queries to template literals
3. SQL remains identical

Critical Warnings

Connection Limits Production Failure

Breaking Point: PostgreSQL default 100 connections
Failure Message: Error: sorry, too many clients already
Impact: Killed Black Friday traffic in production example
Solution: Set explicit limits before hitting them

Transaction Money-Loss Scenario

Failure Mode: Race conditions in financial transactions
Cost: 2 hours downtime when double-withdrawal occurred
Critical Pattern:

async function transferMoney(fromAccount, toAccount, amount) {
  return await db.transaction(async (tx) => {
    // FOR UPDATE locks the row - CRITICAL for money operations
    const balance = await tx`
      SELECT balance FROM accounts WHERE id = ${fromAccount} FOR UPDATE
    `;

    if (balance[0]?.balance < amount) {
      throw new Error('Insufficient funds'); // Auto-rollback
    }

    await tx`UPDATE accounts SET balance = balance - ${amount} WHERE id = ${fromAccount}`;
    await tx`UPDATE accounts SET balance = balance + ${amount} WHERE id = ${toAccount}`;

    return { success: true, transferAmount: amount };
  });
}

Memory Exhaustion Risk

Breaking Point: Loading large datasets without pagination
Failure Mode: Server runs out of memory and dies
Solution: Batch processing with 1000-row limits and garbage collection breaks

Migration Deployment Conflicts

Critical Risk: Multiple deployments running migrations simultaneously
Required: Migration lock table to prevent conflicts
Pattern:

// Prevent simultaneous migrations
const lockAcquired = await db`
  INSERT INTO migration_lock (locked_at) VALUES (NOW())
  ON CONFLICT DO NOTHING
  RETURNING locked_at
`;

Implementation Reality

Error Handling Requirements

Don't Retry: Table doesn't exist (42P01), constraint violations (23505)
Do Retry: Network failures with exponential backoff (max 5 seconds)
Pattern:

async function queryWithRetry(query, values, maxRetries = 3) {
  for (let attempt = 1; attempt <= maxRetries; attempt++) {
    try {
      return await db(query, ...values);
    } catch (error) {
      if (error.code === '42P01' || error.code === '23505') {
        throw error; // Your fault, don't retry
      }

      if (attempt < maxRetries) {
        const delay = Math.min(1000 * Math.pow(2, attempt - 1), 5000);
        await Bun.sleep(delay);
      } else {
        throw new Error(`Gave up after ${maxRetries} attempts: ${error.message}`);
      }
    }
  }
}

Performance Monitoring Thresholds

Slow Query Threshold: 1000ms (adjust based on application)
Batch Size: 1000 rows maximum
Connection Limits: 50+ connections per process sustainable
Garbage Collection: Break every 10,000 rows processed

Production Deployment Requirements

Docker Setup: Use --init flag to prevent signal handling issues
SQLite in Containers: Mount database as volume or data disappears
Connection Pooling: Bun built-in + PgBouncer for high-traffic (recommended combination)
Serverless: SQLite works great, PostgreSQL/MySQL need pooling services

Decision Criteria

When to Choose Bun Database Integration

Worth It Despite: Learning new syntax for existing teams
Major Benefits:

• Eliminates Node.js compilation issues
• Faster connection establishment
• Single runtime (except Prisma)
• Built-in SQLite removes deployment complexity

Not Worth It If:

• Team heavily invested in TypeORM
• Requiring Prisma with frequent schema changes (dual runtime overhead)
• Legacy applications with complex Node.js database middleware

Database Selection Guide

SQLite: Perfect for local dev, testing, serverless edge functions
PostgreSQL: Production apps requiring concurrent writes and complex queries
MySQL: When existing infrastructure requires it, performance similar to PostgreSQL

ORM Migration Decision Matrix

Stay with Prisma: If existing codebase is large and team is productive
Migrate to Drizzle: For performance-critical applications or new projects
Avoid TypeORM: Performance overhead not justified by features

Breaking Points and Failure Modes

Known Issue Patterns

1. SQLite Docker Permissions: Database file permissions in containers
2. Connection String Parsing: MySQL connection string parameter issues
3. Transaction Syntax: SQLite synchronous vs PostgreSQL asynchronous patterns
4. Memory Usage: Large result sets without pagination
5. Migration Conflicts: Concurrent deployment scenarios

Community and Support Quality

Bun Database Support: Active development, responsive to issues
Drizzle Community: High quality, good documentation
Migration Pain Points: Minimal for simple apps, moderate for complex Node.js setups

This technical reference provides all actionable information for implementing Bun database integration while preserving critical operational intelligence about failure modes, performance characteristics, and real-world implementation challenges.