🌌 PG Multiverse

> Multi-cluster PostgreSQL manager for Node.js with TypeScript support


PG Multiverse is a powerful, enterprise-grade PostgreSQL multi-cluster manager that brings advanced database scaling capabilities to Node.js applications. With full TypeScript support, intelligent load balancing, distributed caching, and seamless multi-schema operations.

✨ Features

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- Read/Write Splitting - Automatic query routing to primary/replica clusters
- Intelligent Load Balancing - 5 strategies: round-robin, weighted, least-connections, response-time, health-aware
- Health Monitoring - Continuous health checks with automatic failover
- Multi-Schema Support - Route queries based on schema with zero configuration

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- Distributed Caching - Built-in Redis-like caching with TTL and invalidation
- Connection Pooling - Optimized connection management with warming and metrics
- Distributed Transactions - Cross-cluster ACID transactions with 2PC
- Automatic Failover - Zero-downtime cluster switching

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- Full TypeScript Support - Type-safe queries with generics and interfaces
- Database Migrations - Multi-cluster schema management with TypeScript/JavaScript support
- Zero Configuration - Works out of the box with sensible defaults
- Rich Metrics - Detailed performance monitoring and health statistics
- Event-Driven - Comprehensive event system for monitoring and debugging

🚀 Quick Start

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``bash

Core library

npm install pg-multiverse

Optional: For TypeScript migration support

npm install ts-node

Optional: CLI tools

npm install -g pg-multiverse

or use: npx pgm

`

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`typescript
import { PgMultiverse } from 'pg-multiverse';

// Define your data types
interface User {
id: number;
email: string;
name: string;
active: boolean;
}

// Initialize with cluster configuration
const postgres = new PgMultiverse({
enableCache: true,
enableMetrics: true,
enableTransactions: true
});

await postgres.initialize({
users_cluster: {
schemas: ['users', 'auth'],
primary: {
host: 'primary.db.com',
port: 5432,
database: 'app_users',
user: 'postgres',
password: 'password'
},
replicas: [{
host: 'replica.db.com',
port: 5432,
database: 'app_users',
user: 'postgres',
password: 'password'
}]
}
});

// Type-safe queries with automatic cluster routing
const users = await postgres.query(
'SELECT * FROM users WHERE active = $1',
[true],
{
schema: 'users', // Auto-routes to users_cluster
cache: true, // Cache results
cacheTtl: 300000 // 5 minute cache
}
);

// users.rows is automatically typed as User[]
users.rows.forEach(user => {
console.log(${user.name} <${user.email}>);
});
`

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`typescript
// Enable migrations
const postgres = new PgMultiverse({
enableMigrations: true,
migrations: {
migrationsPath: './migrations',
autoCreateMigrationsTable: true,
},
});

await postgres.initialize(config);

// Run pending migrations
await postgres.migrate();

// Check migration status
const status = await postgres.getMigrationStatus();
console.log(Applied: ${status.appliedMigrations}, Pending: ${status.pendingMigrations});

// Rollback last migration
await postgres.rollback({ steps: 1 });
`

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`typescript
// Cross-cluster transactions
await postgres.withTransaction(['users', 'orders'], async (tx) => {
// Update user in users_cluster
await tx.query(
'UPDATE users SET last_order = NOW() WHERE id = $1',
[userId],
{ schema: 'users' }
);

// Create order in orders_cluster
const order = await tx.query(
'INSERT INTO orders (user_id, total) VALUES ($1, $2) RETURNING *',
[userId, total],
{ schema: 'orders' }
);

return order.rows[0];
});
`

📖 Documentation

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#### Multi-Cluster Architecture

PG Multiverse manages multiple PostgreSQL clusters, each handling specific schemas:

`typescript
const clusterConfig = {
// User data cluster
users_cluster: {
schemas: ['users', 'profiles', 'auth'],
primary: { / primary connection / },
replicas: [{ / replica connections / }],
readPreference: 'replica',
consistencyLevel: 'eventual'
},

// Commerce cluster
commerce_cluster: {
schemas: ['products', 'orders', 'payments'],
primary: { / primary connection / },
readPreference: 'primary',
consistencyLevel: 'strong'
}
};
`

#### Load Balancing Strategies

1. Round Robin (default) - Distributes requests evenly
2. Weighted - Routes based on server weights
3. Least Connections - Prefers servers with fewer active connections
4. Response Time - Routes to fastest responding servers
5. Health Aware - Combines multiple metrics for intelligent routing

`typescript
{
loadBalancing: {
strategy: 'health_aware',
weights: {
'replica_1': 2,
'replica_2': 1
},
healthThreshold: 80
}
}
`

#### Caching System

Built-in distributed caching with multiple invalidation strategies:

`typescript
// Cache with automatic invalidation
await postgres.query('SELECT * FROM products', [], {
schema: 'products',
cache: true,
cacheTtl: 1800000, // 30 minutes
cacheKey: 'all_products',
tags: ['products', 'catalog'] // For bulk invalidation
});

// Invalidate cache
await postgres.invalidateCache({
schema: 'products'
});

await postgres.invalidateCache({
tags: ['products', 'inventory']
});
`

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#### Core Methods

`typescript
class PgMultiverse {
// Initialize with cluster configuration
async initialize(config: ClusterConfiguration): Promise

// Execute type-safe queries
async query(sql: string, params?: any[], options?: QueryOptions): Promise>

// Distributed transactions
async withTransaction(schemas: string[], callback: TransactionCallback): Promise

// Database migrations
async migrate(options?: MigrationExecutionOptions): Promise
async rollback(options?: MigrationRollbackOptions): Promise
async getMigrationStatus(): Promise
async createMigration(name: string, options: MigrationCreateOptions): Promise
getMigrations(): Migration[]
addMigration(migration: Migration): void
getMigrationManager(): MigrationManager

// Health and metrics
async healthCheck(): Promise
getMetrics(): SystemMetrics

// Cache management
async invalidateCache(criteria: InvalidationCriteria): Promise

// Lifecycle
async close(): Promise
}
`

#### Configuration Options

`typescript
interface MultiClusterConfig {
enableCache?: boolean; // Enable distributed caching
enableMetrics?: boolean; // Collect performance metrics
enableTransactions?: boolean; // Enable distributed transactions
enableMigrations?: boolean; // Enable database migrations

cache?: {
maxSize?: number; // Max cache entries (1000)
ttl?: number; // Default TTL in ms (300000)
enableCompression?: boolean; // Compress large entries
};

migrations?: {
migrationsPath?: string; // Path to migration files (./migrations)
migrationsTable?: string; // Control table name
lockTable?: string; // Locking table name
autoCreateMigrationsTable?: boolean; // Auto-create control tables
validateChecksums?: boolean; // Validate migration integrity
allowOutOfOrder?: boolean; // Require sequential execution
lockTimeout?: number; // Lock timeout in ms (60000)
batchSize?: number; // Batch size for parallel execution
logger?: MigrationLogger; // Custom logger instance
};

cluster?: {
healthCheckInterval?: number; // Health check frequency (30000ms)
retryAttempts?: number; // Connection retry attempts (3)
maxFailuresBeforeMarkDown?: number; // Failures before marking down (3)
};
}
`

🗄️ Database Migrations

PG Multiverse includes a powerful migration system that supports multi-cluster and multi-schema databases with both TypeScript and JavaScript.

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`typescript
const postgres = new PgMultiverse({
enableMigrations: true,
migrations: {
migrationsPath: './migrations', // Path to migration files
migrationsTable: 'pg_multiverse_migrations', // Control table name
lockTable: 'pg_multiverse_migration_locks', // Locking table name
autoCreateMigrationsTable: true, // Auto-create control tables
validateChecksums: true, // Validate migration integrity
allowOutOfOrder: false, // Require sequential execution
lockTimeout: 60000, // Lock timeout in ms
batchSize: 100, // Batch size for parallel execution
logger: customLogger // Custom logger instance
}
});
`

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#### TypeScript Migrations

`typescript
// migrations/20241230120000_create_users.ts
import { Migration, MigrationContext } from 'pg-multiverse';

const migration: Migration = {
version: '20241230120000_create_users',
name: 'create_users',
description: 'Create users table with profiles',
targetSchemas: ['users', 'auth'],
targetClusters: ['users_cluster'], // Optional: specific clusters
dependencies: ['20241230110000_create_base'], // Optional: dependencies
tags: ['users', 'initial'], // Optional: tags for organization
createdAt: new Date(),

async up(context: MigrationContext): Promise {
context.logger.info(Creating users table in ${context.schema});

// Type-safe query execution
await context.query(
CREATE TABLE users (
id SERIAL PRIMARY KEY,
email VARCHAR(255) UNIQUE NOT NULL,
name VARCHAR(255) NOT NULL,
active BOOLEAN DEFAULT true,
created_at TIMESTAMP DEFAULT NOW()
)
);

// Insert seed data
await context.query(
INSERT INTO users (email, name) VALUES
($1, $2), ($3, $4)
, ['admin@example.com', 'Admin', 'user@example.com', 'User']);

context.logger.info('Users table created successfully');
},

async down(context: MigrationContext): Promise {
context.logger.info(Dropping users table from ${context.schema});
await context.query(DROP TABLE IF EXISTS users);
context.logger.info('Users table dropped successfully');
}
};

export default migration;
`

#### JavaScript Migrations

`javascript
// migrations/20241230130000_add_profiles.js
const migration = {
version: '20241230130000_add_profiles',
name: 'add_profiles',
description: 'Add user profiles functionality',
targetSchemas: ['users'],
createdAt: new Date(),

async up(context) {
await context.query(
CREATE TABLE profiles (
user_id INTEGER PRIMARY KEY REFERENCES users(id),
bio TEXT,
avatar_url VARCHAR(500),
settings JSONB DEFAULT '{}'
)
);
},

async down(context) {
await context.query(DROP TABLE IF EXISTS profiles);
}
};

module.exports = migration;
`

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#### Running Migrations

`typescript
// Run all pending migrations
await postgres.migrate();

// Run migrations with options
await postgres.migrate({
targetVersion: '20241230120000_create_users', // Run up to specific version
targetSchemas: ['users', 'auth'], // Specific schemas only
targetClusters: ['users_cluster'], // Specific clusters only
dryRun: true, // Show what would run without executing
parallel: true, // Run in parallel where possible
maxParallel: 4, // Max parallel executions
continueOnError: false, // Stop on first error
});

// Run with detailed progress monitoring
postgres.getMigrationManager().on('migrationStarted', (data) => {
console.log(⚡ Starting: ${data.name} on ${data.schema}@${data.cluster});
});

postgres.getMigrationManager().on('migrationCompleted', (data) => {
console.log(✅ Completed: ${data.name} (${data.duration}ms));
});
`

#### Rollback Operations

`typescript
// Rollback last migration
await postgres.rollback({ steps: 1 });

// Rollback to specific version
await postgres.rollback({
targetVersion: '20241230110000_create_base',
targetSchemas: ['users'],
dryRun: true // Preview rollback without executing
});

// Rollback with error handling
try {
await postgres.rollback({ steps: 2, force: true });
} catch (error) {
console.error('Rollback failed:', error.message);
}
`

#### Migration Status and Management

`typescript
// Get comprehensive status
const status = await postgres.getMigrationStatus();
console.log(Total: ${status.totalMigrations});
console.log(Applied: ${status.appliedMigrations});
console.log(Pending: ${status.pendingMigrations});

// Status by schema
Object.entries(status.bySchema).forEach(([schema, stats]) => {
console.log(${schema}: ${stats.applied} applied, ${stats.pending} pending);
if (stats.lastApplied) {
console.log( Last applied: ${stats.lastApplied});
}
});

// Status by cluster
Object.entries(status.byCluster).forEach(([cluster, stats]) => {
console.log(${cluster}: ${stats.applied} applied, ${stats.pending} pending);
});

// List all available migrations
const migrations = postgres.getMigrations();
migrations.forEach(migration => {
console.log(${migration.version}: ${migration.name});
console.log( Schemas: ${migration.targetSchemas.join(', ')});
console.log( Description: ${migration.description});
});
`

#### Creating Migration Files

`typescript
// Create new migration file
const filePath = await postgres.createMigration('add_user_permissions', {
targetSchemas: ['users', 'auth'],
targetClusters: ['users_cluster'],
description: 'Add user permissions and roles system',
tags: ['permissions', 'security']
});

console.log(Migration created: ${filePath});
`

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Install the CLI globally or use npx:

`bash
npm install -g pg-multiverse

or use npx pg-multiverse

`

#### CLI Commands

`bash

Create a new migration

pgm create add_user_roles --schemas users,auth --description "Add role-based permissions"

Run migrations

pgm migrate # Run all pending
pgm migrate --target 20241230120000 # Run up to specific version
pgm migrate --schemas users,products # Specific schemas only
pgm migrate --parallel # Run in parallel
pgm migrate --dry-run # Preview without executing

Check status

pgm status # Overall status
pgm status --schemas users # Schema-specific status
pgm status --verbose # Detailed information

Rollback migrations

pgm rollback --steps 1 # Rollback last migration
pgm rollback --target 20241230110000 # Rollback to specific version
pgm rollback --dry-run # Preview rollback

List migrations

pgm list # Show all migrations
pgm list --verbose # Show detailed information

Global options

pgm --config config.json # Use custom config file
pgm --migrations ./db/migrations # Custom migrations path
pgm --verbose # Verbose output
`

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#### Cross-Cluster Dependencies

`typescript
const migration: Migration = {
version: '20241230150000_create_orders',
name: 'create_orders',
targetSchemas: ['orders'],
dependencies: ['20241230120000_create_users'], // Users must exist first

async up(context) {
// Reference data from other clusters is handled automatically
await context.query(
CREATE TABLE orders (
id SERIAL PRIMARY KEY,
user_email VARCHAR(255) NOT NULL, -- Reference to users cluster
total DECIMAL(10,2) NOT NULL,
status VARCHAR(50) DEFAULT 'pending'
)
);
}
};
`

#### Conditional Migrations

`typescript
const migration: Migration = {
version: '20241230160000_conditional_update',
name: 'conditional_update',
targetSchemas: ['users'],

async up(context) {
// Check if column exists before adding
const result = await context.query(
SELECT column_name
FROM information_schema.columns
WHERE table_name = 'users' AND column_name = 'last_login'
);

if (result.rows.length === 0) {
await context.query(
ALTER TABLE users ADD COLUMN last_login TIMESTAMP
);
context.logger.info('Added last_login column');
} else {
context.logger.info('last_login column already exists, skipping');
}
}
};
`

#### Data Migrations with Batching

`typescript
const migration: Migration = {
version: '20241230170000_migrate_user_data',
name: 'migrate_user_data',
targetSchemas: ['users'],

async up(context) {
// Process large datasets in batches
let offset = 0;
const batchSize = 1000;
let hasMore = true;

while (hasMore) {
const users = await context.query(
SELECT id, old_field
FROM users
WHERE new_field IS NULL
LIMIT $1 OFFSET $2
, [batchSize, offset]);

if (users.rows.length === 0) {
hasMore = false;
break;
}

// Process batch
for (const user of users.rows) {
await context.query(
UPDATE users
SET new_field = $1
WHERE id = $2
, [processOldField(user.old_field), user.id]);
}

offset += batchSize;
context.logger.info(Processed ${offset} users);
}
}
};
`

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#### 1. Naming Convention
`
YYYYMMDDHHMMSS_descriptive_name.ts
20241230120000_create_users_table.ts
20241230130000_add_user_permissions.ts
20241230140000_migrate_legacy_data.ts
`

#### 2. Schema Organization
- Group related tables in the same migration
- Use descriptive names and comments
- Always provide rollback functionality

#### 3. Production Safety
`typescript
// Always test with dry-run first
await postgres.migrate({ dryRun: true });

// Use transactions for complex migrations
const migration: Migration = {
async up(context) {
await context.query('BEGIN');
try {
await context.query('-- complex operations');
await context.query('COMMIT');
} catch (error) {
await context.query('ROLLBACK');
throw error;
}
}
};
`

#### 4. Error Handling
`typescript
// Comprehensive error handling
postgres.getMigrationManager().on('migrationFailed', (data) => {
console.error(❌ Migration ${data.name} failed:, data.error.message);
// Send alerts, log to monitoring system, etc.
});
`

🏗️ Advanced Usage

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`typescript
{
orders_cluster: {
schemas: ['orders'],
sharding: {
strategy: 'hash',
key: 'user_id',
partitions: 4
},
primary: { / config / },
replicas: [
{ / shard 1 replica / },
{ / shard 2 replica / },
{ / shard 3 replica / },
{ / shard 4 replica / }
]
}
}
`

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`typescript
// Register schemas at runtime
postgres.registerSchema('analytics', 'analytics_cluster', {
cacheStrategy: 'aggressive',
priority: 3
});

// Query the new schema
const events = await postgres.query(
'SELECT * FROM events WHERE date > $1',
[startDate],
{ schema: 'analytics' }
);
`

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`typescript
// Monitor cluster health
postgres.on('clusterDown', ({ clusterId, reason }) => {
console.error(Cluster ${clusterId} is down: ${reason});
// Trigger alerts, logging, etc.
});

postgres.on('clusterRecovered', ({ clusterId, downtime }) => {
console.log(Cluster ${clusterId} recovered after ${downtime}ms);
});

// Monitor cache performance
postgres.on('cacheHit', ({ key, schema }) => {
console.log(Cache hit for ${key} in schema ${schema});
});

// Monitor query performance
postgres.on('queryExecuted', ({ duration, clusterId }) => {
if (duration > 1000) {
console.warn(Slow query detected: ${duration}ms on ${clusterId});
}
});
`

🧪 Testing

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`bash
npm test
`

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`bash

With real PostgreSQL instances

npm run test:integration
`

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`bash
npm run test:coverage
`

📊 Monitoring & Metrics

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`typescript
const metrics = postgres.getMetrics();

console.log(Total Queries: ${metrics.totalQueries});
console.log(Average Response Time: ${metrics.avgResponseTime}ms);
console.log(Error Rate: ${metrics.errorRate}%);

// Per-cluster metrics
Object.entries(metrics.clusters).forEach(([clusterId, stats]) => {
console.log(${clusterId}: ${stats.queries.total} queries, ${stats.connections.active} active connections);
});

// Cache performance
if (metrics.cache) {
console.log(Cache Hit Rate: ${(metrics.cache.hitRate * 100).toFixed(2)}%);
console.log(Cache Size: ${metrics.cache.itemCount} items);
}
`

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`typescript
const health = await postgres.healthCheck();

Object.entries(health).forEach(([clusterId, status]) => {
console.log(${clusterId}: ${status.healthy ? '✅' : '❌'} (${status.responseTime}ms));

if (!status.healthy) {
console.error(Error: ${status.error});
console.log(Failure Count: ${status.failureCount});
}
});
`

🚀 Performance

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| Feature | Performance |
|---------|-------------|
| Connection Pooling | 10,000+ concurrent connections |
| Query Caching | 95%+ cache hit rates |
| Load Balancing | Sub-1ms routing overhead |
| Health Checks | 30s intervals, <5ms latency |
| Failover Time | <2s automatic recovery |

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1. Connection Tuning

`typescript
{
connectionPool: {
min: 5, // Always keep 5 connections warm
max: 50, // Scale up to 50 under load
warmupConnections: true
}
}
`

2. Cache Optimization

`typescript
{
cache: {
maxSize: 10000, // Increase for high-traffic apps
enableCompression: true, // Save memory on large results
compressionThreshold: 1024
}
}
`

3. Health Check Tuning

`typescript
{
cluster: {
healthCheckInterval: 15000, // More frequent checks
maxFailuresBeforeMarkDown: 5 // More resilient to transient issues
}
}
`

🌍 Use Cases

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- User Cluster: customers, profiles, authentication
- Catalog Cluster: products, categories, inventory
- Order Cluster: orders, payments, shipping
- Analytics Cluster: events, metrics, reports
- Schema Evolution: Coordinated migrations across all clusters

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- Tenant Isolation: Separate clusters per tier
- Shared Services: Common clusters for billing, analytics
- Geographic Distribution: Region-specific clusters
- Rolling Updates: Zero-downtime schema migrations per tenant

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- Service Isolation: One cluster per microservice
- Cross-service Transactions: Distributed transactions
- Centralized Monitoring: Unified metrics and health
- Independent Deployments: Service-specific migration management

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- OLTP/OLAP Separation: Transactional vs analytical workloads
- Read Scaling: Multiple read replicas
- Cache Optimization: Aggressive caching for hot data
- Data Pipeline Management: Automated migrations for ETL processes

📦 Migration Guide

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`typescript
// Before: Direct pg usage
import { Pool } from 'pg';
const pool = new Pool({ / config / });
const result = await pool.query('SELECT * FROM users');

// After: PG Multiverse with type safety
import { PgMultiverse } from 'pg-multiverse';
const postgres = new PgMultiverse();
await postgres.initialize(config);
const result = await postgres.query('SELECT * FROM users');
`

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1. Start with single cluster
2. Add read replicas
3. Introduce schema-based routing
4. Scale to multiple clusters

🤝 Contributing

We welcome contributions! Please see our Contributing Guide.

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`bash

Clone the repository

git clone https://github.com/andeerc/pg-multiverse.git
cd pg-multiverse

Install dependencies

npm install

Run tests

npm test

Build the project

npm run build
``

📝 Changelog

See CHANGELOG.md for version history.

📜 License

MIT © PG Multiverse Team

🙏 Acknowledgments

- PostgreSQL Community - For the amazing database
- Node.js pg Driver - Reliable PostgreSQL connectivity
- TypeScript Team - Type safety and developer experience
- Contributors - Everyone who helped make this project better

---