| Update History | Comment |
|---|---|
| 2024/03/26 | Initial version. |
| 2025/04/25 | Update for 2025. Add charts, optimization strategy. |
My co-founder Danny and I build the first version of Google Cloud SQL for PostgreSQL. If you have ever wondered what the heck cloudsqlsuperuser is, that was Danny's legacy:) Occasionally, we get asked about AlloyDB for PostgreSQL and whether it's worthwhile to migrate from Cloud SQL. Below I collect some pricing notes.
Introduction
AlloyDB is Google Cloud's fully managed PostgreSQL-compatible database service designed for demanding enterprise workloads. It's positioned as the premium upgrade from Google Cloud SQL for PostgreSQL, offering enhanced performance, availability, and advanced features for mission-critical applications.
For customers migrating from Google Cloud SQL, other cloud database services like AWS Aurora, or on-premises PostgreSQL deployments, understanding AlloyDB's pricing structure is essential for accurate budgeting and cost optimization. This comprehensive guide explores AlloyDB pricing in detail, comparing it with alternatives and providing strategies to maximize your investment.
Summary of Pricing Tiers
Different tiers in us-east1 according to the Google Cloud pricing calculator as of April 2025:
| Tier | Spec | Monthly cost |
|---|---|---|
| Low-end | Cloud SQL Enterprise, 1c3.75G, 100 GB storage, HA | $130 |
| Middle-end | Cloud SQL Enterprise, 2c16G, 100 GB storage, HA | $315 |
| Middle-end | Cloud SQL Enterprise Plus, 2c16g, 100 GB storage, HA, Data Cache | $521 |
| Middle-end | AlloyDB, 2c16g, 100 GB storage, HA | $546 |
| High-end | Cloud SQL Enterprise Plus, 96c768g, 1000 GB storage, HA, Data Cache | $19,966 |
| High-end | AlloyDB, 96c768g, 1000 GB storage, HA | $24,977 |
AlloyDB pricing follows a predictable model similar to Cloud SQL, with charges based on computing resources (vCPU/memory), storage, and networking. While AlloyDB commands a premium over Cloud SQL, this markup reflects its enhanced performance capabilities, advanced features, and enterprise-grade architecture.
Unlike AWS Aurora, which uses a less-predictable, request-based pricing model (charging per million requests), AlloyDB offers transparent resource-based pricing that makes budgeting more straightforward. This predictability is particularly valuable for enterprises with stable workloads seeking to avoid billing surprises.
AlloyDB Architecture and Pricing Components
Understanding AlloyDB's architecture is key to grasping its pricing model. AlloyDB is organized into clusters containing different types of instances:
- Primary instance: The read-write instance that serves as the main database
- Read pool instances: Optional read-only instances that scale read capacity
- Secondary instances: Optional instances in different regions for disaster recovery
Each instance can be configured with different amounts of compute resources (vCPU and memory) and can be either highly available (HA) with standby nodes across multiple zones or basic (non-HA) with a single node in one zone.
AlloyDB's pricing breaks down into four main components:
- CPU and memory: Resources allocated to your instances
- Storage: Data storage, backup storage, and transaction logs
- Networking: Data transfer between regions and to the internet
Let's examine each component in detail.
CPU and Memory Pricing
| USD per month (us-east1) | AlloyDB | Cloud SQL Enterprise Plus | Cloud SQL Enterprise | GCE N2 |
|---|---|---|---|---|
| Per vCPU | $54.5091 | $39.201 | $30.149 | $23.07603 |
| Per GB memory | $9.2418 | $6.643 | $5.11 | $3.09301 |
AlloyDB's compute pricing reflects its position as a premium database service:
- AlloyDB has a 39% markup over Cloud SQL Enterprise Plus
- Cloud SQL Enterprise Plus has a 30% markup over Cloud SQL Enterprise
- Cloud SQL Enterprise has a 30% markup for vCPU and 65% markup for memory over the underlying GCE N2 instance type
This tiered pricing structure corresponds to increasing levels of performance, features, and management capabilities across the product line.
Committed Use Discounts
Both AlloyDB and Cloud SQL offer the same committed use discounts:
- 1-year commitment: 25% discount (pay 75% of on-demand price)
- 3-year commitment: 52% discount (pay 48% of on-demand price)
These discounts can significantly reduce costs for stable, predictable workloads.
High Availability Pricing
High availability (HA) configurations, which provide automated failover capabilities across multiple zones, double the compute costs for both AlloyDB and Cloud SQL. While this represents a substantial increase, the business continuity benefits often justify the investment for production workloads.
Capacity Limits
AlloyDB offers substantial scalability with support for:
- Up to 128 vCPUs per instance
- Up to 864 GB of memory per instance
- Up to 20 read pool instances per cluster for horizontal scaling
This allows AlloyDB to handle enterprise-scale workloads while maintaining performance.
Storage Pricing
| USD per month (us-east1) | AlloyDB | Cloud SQL Enterprise Plus | Cloud SQL Enterprise |
|---|---|---|---|
| Per GB data | $0.338939 | $0.17 SSD, $0.09 HDD (2x for HA) | Same as Plus |
| Per GB backup | $0.113004 | $0.08 | Same as Plus |
| Per GB transaction log | $0.113004 (first 7 days free) | N/A | N/A |
AlloyDB uses an intelligent regional storage system that automatically scales based on your needs. Key aspects of AlloyDB storage pricing include:
Regional Storage System
AlloyDB's storage architecture separates compute from storage, allowing for:
- Independent scaling of compute and storage resources
- Storage sharing across all instances in a cluster
- Consistent storage costs when horizontally scaling with read pool instances
This architecture is particularly beneficial for read-heavy workloads, as you can add read capacity without increasing storage costs.
Log-Based Architecture
AlloyDB's log-based architecture includes transaction logs as part of its backup and recovery system:
- First seven days of transaction logs are retained at no extra charge
- Logs beyond seven days are charged at the same rate as backup storage
- This architecture enables point-in-time recovery and efficient cross-region replication
Storage Pricing Comparison
AlloyDB's storage is priced higher than Cloud SQL, reflecting its advanced storage architecture:
- AlloyDB data storage ($0.338939/GB) is approximately twice the cost of Cloud SQL SSD storage ($0.17/GB)
- AlloyDB backup storage ($0.113004/GB) is about 40% more expensive than Cloud SQL backup storage ($0.08/GB)
- AlloyDB's transaction log storage is unique to its architecture and has no direct equivalent in Cloud SQL
Despite the higher per-GB cost, AlloyDB's storage system can be more cost-effective for certain workloads due to its efficiency and shared nature across instances.
Networking Pricing
Networking costs are consumption-based for both AlloyDB and Cloud SQL, making them inherently less predictable than compute and storage costs. Understanding these costs is particularly important for deployments using cross-region replication or serving global audiences.
Data Transfer Within Google Cloud
AlloyDB provides more granular pricing for cross-region data transfer compared to Cloud SQL:
Cross-Region Data Transfer (Northern America to Europe)
- AlloyDB: $0.05/GB
- Cloud SQL: $0.12/GB (if not intra-continental)
This more granular pricing can lead to significant savings for workloads with specific regional traffic patterns.
Internet Egress Pricing
AlloyDB also offers tiered pricing for internet egress based on volume and region:
Internet Egress (Within North America)
- AlloyDB: $0.12/GB for 0-1TB, $0.11/GB for 1-10TB, $0.08/GB for 10+TB
- Cloud SQL: $0.19/GB (not using Cloud Interconnect)
For high-volume outbound traffic, AlloyDB's tiered pricing can provide substantial savings.
Cross-Region Replication Considerations
Cross-region replication is a key feature for disaster recovery and global distribution of data. While both AlloyDB and Cloud SQL support this capability, AlloyDB's implementation is more performant and feature-rich:
- AlloyDB supports up to five secondary clusters for a primary cluster
- Each secondary cluster can have up to 20 read pool instances
- Secondary clusters can be promoted to primary clusters in disaster scenarios
- Switchover with zero data loss is supported for planned migrations
When planning cross-region deployments, consider both the data transfer costs and the performance benefits of AlloyDB's replication architecture.
Cost Optimization Strategies
1. Use Basic Instances for Non-Production Environments
- Deploy basic (non-HA) instances for development, testing, and staging
- Save approximately 50% on compute costs compared to HA instances
- Easily upgrade to HA when moving to production
2. Leverage Committed Use Discounts
- Analyze your workload stability to determine commitment eligibility
- Consider 1-year commitments (25% discount) for newer applications
- Use 3-year commitments (52% discount) for stable, long-term workloads
3. Right-Size Your Instances
- Monitor CPU and memory usage to identify over-provisioned resources
- Scale instances up or down based on actual requirements
- Consider vertical scaling for primary instances and horizontal scaling with read pools for read-heavy workloads
4. Optimize Storage Usage
- Take advantage of AlloyDB's automatic storage scaling
- Monitor transaction ID usage to prevent vacuum-related issues
- Configure appropriate backup retention periods based on compliance requirements
5. Reduce Networking Costs
- Co-locate related resources in the same region when possible
- Be strategic about cross-region replication based on pricing tiers
- Consider data transfer costs when designing multi-region architectures
6. Implement Performance Best Practices
- Add read pool instances to offload read traffic from primary instances
- Enable the Columnar Engine for analytical queries to improve performance
- Split large instances into smaller instances where possible
- Keep database table count under 10,000 to optimize performance
7. Monitor and Optimize Continuously
- Use AlloyDB tools like performance snapshot reports and query insights
- Configure maintenance windows to minimize disruption
- Set up alerts for resource utilization thresholds
- Regularly review and adjust your configuration based on changing workload patterns
Real-World Pricing Examples
To illustrate AlloyDB pricing in practice, let's examine some real-world scenarios:
Example 1: E-commerce Database (Middle Tier)
Configuration:
- 8 vCPU, 64 GB memory primary instance (HA)
- 2 read pool instances with 4 vCPU, 32 GB memory each
- 500 GB storage
- 1 TB monthly data transfer between regions
Monthly cost breakdown:
- Compute (primary): $1,090 (8 vCPU × $54.51 × 2 for HA + 64 GB × $9.24 × 2 for HA)
- Compute (read pools): $545 (2 instances × 4 vCPU × $54.51 + 2 instances × 32 GB × $9.24)
- Storage: $169 (500 GB × $0.339)
- Backup: $56 (500 GB × $0.113)
- Data transfer: $50 (1 TB × $0.05 between North America and Europe)
- Total: Approximately $1,910 per month
With a 1-year commitment, this would reduce to approximately $1,570 per month.
Example 2: Financial Services OLTP Workload (High Tier)
Configuration:
- 32 vCPU, 256 GB memory primary instance (HA)
- 4 read pool instances with 16 vCPU, 128 GB memory each
- 2 TB storage
- 5 TB monthly data transfer between regions
Monthly cost breakdown:
- Compute (primary): $4,360 (32 vCPU × $54.51 × 2 for HA + 256 GB × $9.24 × 2 for HA)
- Compute (read pools): $4,360 (4 instances × 16 vCPU × $54.51 + 4 instances × 128 GB × $9.24)
- Storage: $678 (2 TB × $0.339)
- Backup: $226 (2 TB × $0.113)
- Data transfer: $250 (5 TB × $0.05 between North America and Europe)
- Total: Approximately $9,874 per month
With a 3-year commitment, this would reduce to approximately $5,740 per month.
