Aurora Global Database

The multi-region shopping mall platform uses Aurora PostgreSQL Global Database to implement cross-region data replication. The Writer instance is in us-east-1, and us-west-2 operates as a Read Replica, forwarding write requests to the primary through Write Forwarding.

Architecture

Cluster Specifications

Item	us-east-1 (Primary)	us-west-2 (Secondary)
Cluster ID	`production-aurora-global-us-east-1`	`production-aurora-global-us-west-2`
Engine	Aurora PostgreSQL 15.8	Aurora PostgreSQL 15.8
Writer Instance	db.r6g.2xlarge (1)	-
Reader Instances	db.r6g.xlarge (2)	db.r6g.xlarge (2)
Replication Lag	-	< 1 second
Write Forwarding	-	Enabled
Encryption	KMS (per-region key)	KMS (per-region key)

Connection Endpoints

us-east-1

Endpoint Type	Value
Writer	`production-aurora-global-us-east-1.cluster-xxxxxxxxxxxx.us-east-1.rds.amazonaws.com`
Reader	`production-aurora-global-us-east-1.cluster-ro-xxxxxxxxxxxx.us-east-1.rds.amazonaws.com`
Port	5432

us-west-2

Endpoint Type	Value
Reader	`production-aurora-global-us-west-2.cluster-yyyyyyyyyyyy.us-west-2.rds.amazonaws.com`
Reader (RO)	`production-aurora-global-us-west-2.cluster-ro-yyyyyyyyyyyy.us-west-2.rds.amazonaws.com`
Port	5432

Terraform Configuration

resource "aws_rds_cluster" "this" {
  cluster_identifier        = "${var.environment}-aurora-global-${var.region}"
  global_cluster_identifier = var.is_primary ? null : var.global_cluster_identifier

  engine         = "aurora-postgresql"
  engine_version = "15.8"

  # Primary cluster credentials
  master_username = var.is_primary ? "mall_admin" : null
  master_password = var.is_primary ? var.master_password : null

  # Secondary cluster - Write Forwarding
  source_region                  = var.is_primary ? null : var.source_region
  enable_global_write_forwarding = var.is_primary ? null : var.enable_write_forwarding

  db_subnet_group_name   = aws_db_subnet_group.this.name
  vpc_security_group_ids = [var.security_group_id]

  storage_encrypted = true
  kms_key_id        = var.kms_key_arn

  backup_retention_period      = var.is_primary ? var.backup_retention_period : 1
  preferred_backup_window      = "03:00-04:00"
  preferred_maintenance_window = "sun:04:00-sun:05:00"

  enabled_cloudwatch_logs_exports = ["postgresql"]
  deletion_protection             = true
}

# Writer Instance (Primary only)
resource "aws_rds_cluster_instance" "writer" {
  count = var.is_primary ? 1 : 0

  identifier         = "${var.environment}-aurora-global-${var.region}-writer"
  cluster_identifier = aws_rds_cluster.this.id
  instance_class     = var.writer_instance_class  # db.r6g.2xlarge

  monitoring_interval             = 60
  performance_insights_enabled    = true
  performance_insights_kms_key_id = var.kms_key_arn
}

# Reader Instances
resource "aws_rds_cluster_instance" "readers" {
  count = var.reader_count  # 2

  identifier         = "${var.environment}-aurora-global-${var.region}-reader-${count.index + 1}"
  cluster_identifier = aws_rds_cluster.this.id
  instance_class     = var.reader_instance_class  # db.r6g.xlarge

  monitoring_interval             = 60
  performance_insights_enabled    = true
  performance_insights_kms_key_id = var.kms_key_arn
}

Database Schema

The following tables are stored in Aurora PostgreSQL:

users table

CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    email VARCHAR(255) UNIQUE NOT NULL,
    password_hash VARCHAR(255) NOT NULL,
    name VARCHAR(100) NOT NULL,
    phone VARCHAR(20),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    last_login_at TIMESTAMP,
    status VARCHAR(20) DEFAULT 'active'
);

CREATE INDEX idx_users_email ON users(email);
CREATE INDEX idx_users_status ON users(status);

orders table

CREATE TABLE orders (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    user_id UUID NOT NULL REFERENCES users(id),
    status VARCHAR(50) NOT NULL DEFAULT 'pending',
    total_amount DECIMAL(12, 2) NOT NULL,
    currency VARCHAR(3) DEFAULT 'KRW',
    shipping_address JSONB,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    completed_at TIMESTAMP,
    region VARCHAR(20) NOT NULL
);

CREATE INDEX idx_orders_user_id ON orders(user_id);
CREATE INDEX idx_orders_status ON orders(status);
CREATE INDEX idx_orders_created_at ON orders(created_at);
CREATE INDEX idx_orders_region ON orders(region);

payments table

CREATE TABLE payments (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    order_id UUID NOT NULL REFERENCES orders(id),
    amount DECIMAL(12, 2) NOT NULL,
    currency VARCHAR(3) DEFAULT 'KRW',
    method VARCHAR(50) NOT NULL,
    status VARCHAR(50) NOT NULL DEFAULT 'pending',
    provider VARCHAR(50),
    transaction_id VARCHAR(255),
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    completed_at TIMESTAMP
);

CREATE INDEX idx_payments_order_id ON payments(order_id);
CREATE INDEX idx_payments_status ON payments(status);

inventory table

CREATE TABLE inventory (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    product_id UUID NOT NULL,
    warehouse_id UUID NOT NULL,
    quantity INTEGER NOT NULL DEFAULT 0,
    reserved_quantity INTEGER NOT NULL DEFAULT 0,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE(product_id, warehouse_id)
);

CREATE INDEX idx_inventory_product_id ON inventory(product_id);
CREATE INDEX idx_inventory_warehouse_id ON inventory(warehouse_id);

shipments table

CREATE TABLE shipments (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    order_id UUID NOT NULL REFERENCES orders(id),
    carrier VARCHAR(50) NOT NULL,
    tracking_number VARCHAR(100),
    status VARCHAR(50) NOT NULL DEFAULT 'preparing',
    shipped_at TIMESTAMP,
    delivered_at TIMESTAMP,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE INDEX idx_shipments_order_id ON shipments(order_id);
CREATE INDEX idx_shipments_tracking_number ON shipments(tracking_number);

Write Forwarding

When applications in the secondary region perform write operations, Aurora automatically forwards requests to the primary Writer.

Write Forwarding Considerations

Item	Description
Latency	Additional latency due to extra network hop (~50-100ms)
Transactions	Supported (recommended within single region only)
Read Consistency	Choose from SESSION, EVENTUAL, GLOBAL
Failure Handling	Write fails if primary is down

Monitoring

CloudWatch Metrics

resource "aws_cloudwatch_metric_alarm" "aurora_cpu" {
  alarm_name          = "${var.environment}-aurora-cpu-high"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 3
  metric_name         = "CPUUtilization"
  namespace           = "AWS/RDS"
  period              = 60
  statistic           = "Average"
  threshold           = 80
  alarm_description   = "Aurora CPU utilization is high"

  dimensions = {
    DBClusterIdentifier = aws_rds_cluster.this.cluster_identifier
  }
}

resource "aws_cloudwatch_metric_alarm" "aurora_replication_lag" {
  alarm_name          = "${var.environment}-aurora-replication-lag"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = 3
  metric_name         = "AuroraGlobalDBReplicationLag"
  namespace           = "AWS/RDS"
  period              = 60
  statistic           = "Average"
  threshold           = 1000  # 1 second
  alarm_description   = "Aurora global replication lag is high"

  dimensions = {
    DBClusterIdentifier = aws_rds_cluster.this.cluster_identifier
  }
}

Performance Insights

Performance Insights is enabled on all instances for query performance analysis:

Top SQL: Queries using the most resources
Wait Events: Wait event analysis
DB Load: Database load trends

Disaster Recovery

Automatic Failover

When the Writer fails within a region, a Reader is automatically promoted:

Writer instance failure detected (~30 seconds)
One of the Readers is promoted to Writer
Endpoint DNS update (~30 seconds)

Regional Failover

In case of complete primary region failure:

# Promote secondary to primary
aws rds failover-global-cluster \
  --global-cluster-identifier production-aurora-global \
  --target-db-cluster-identifier production-aurora-global-us-west-2

Caution

Regional failover must be performed manually. Automatic global failover is not supported.

Next Steps

DocumentDB Global Cluster - MongoDB-compatible database
ElastiCache Global Datastore - Redis-compatible cache

Architecture​

Cluster Specifications​

Connection Endpoints​

us-east-1​

us-west-2​

Terraform Configuration​

Database Schema​

users table​

orders table​

payments table​

inventory table​

shipments table​

Write Forwarding​

Write Forwarding Considerations​

Monitoring​

CloudWatch Metrics​

Performance Insights​

Disaster Recovery​

Automatic Failover​

Regional Failover​

Next Steps​