Google Cloud Spanner
Google's horizontally scalable, globally distributed relational database with strong ACID consistency, SQL interface, and automatic sharding for planet-scale applications.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
IAM fine-grained roles; VPC Service Controls for network isolation; CMEK for encryption key control.
⚡ Reliability
Best When
You need the scalability of NoSQL with the consistency guarantees of a relational database across multiple global regions.
Avoid When
Your workload fits in a single region or can be handled by Postgres/AlloyDB at fraction of the cost.
Use Cases
- • Global agent state stores requiring strong consistency across multiple regions
- • Multi-region transactional workloads where Postgres can't scale horizontally
- • Financial ledger systems needing ACID guarantees at global scale
- • Agent coordination databases where multiple agents worldwide read/write shared state
- • High-throughput OLTP workloads that need automatic horizontal scaling without schema changes
Not For
- • Small-scale applications — minimum $0.90/hour (1 processing unit) makes it expensive for dev/small prod
- • Read-heavy analytics workloads (use BigQuery)
- • Teams not on GCP or unwilling to pay premium for global distribution
Interface
Authentication
GCP IAM with service account credentials or Application Default Credentials. Fine-grained IAM roles (roles/spanner.databaseReader vs Writer). Managed Identity recommended.
Pricing
Very expensive for small workloads. Regional (single-region) is cheapest; multi-region 2x-4x cost. Enterprise pricing available.
Agent Metadata
Known Gotchas
- ⚠ Mutations vs DML: mutations batch write without read, DML is SQL INSERT/UPDATE — mixing them incorrectly causes session errors
- ⚠ Stale reads (bounded staleness) are much cheaper and faster than strong reads — use for agent cache reads
- ⚠ Schema changes (DDL) are async operations — poll for completion before running DML against new schema
- ⚠ Session pool management is critical — SDK manages pool but leaked sessions cause RESOURCE_EXHAUSTED errors
- ⚠ Spanner doesn't support sequences/auto-increment — use UUID or bit-reversed sequence pattern for primary keys
Alternatives
Full Evaluation Report
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Package Brief
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Scores are editorial opinions as of 2026-03-06.