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Datomic vs PostgreSQL

Datomic: Immutable Datalog database from Nubank where every fact is timestamped and queries run in the app process. PostgreSQL: The extensible, standards-first open-source relational database.

key differences

  • Horizontal scaling is none in Datomic and addon in PostgreSQL.
  • Only Datomic has time travel.
  • Only PostgreSQL has vector search, geospatial, json, triggers, stored procedures.
  • Datomic can run embedded in your application process.

choose datomic for

  • +Financial and banking domain models needing auditability
  • +Systems that must answer what was known at a given time
  • +Complex domain graphs in Clojure services

best at · OLTP, Event sourcing, Ledger

choose postgresql for

  • +General-purpose application backend
  • +SaaS multi-tenant data
  • +Geospatial applications with PostGIS
  • +Semantic search alongside relational data with pgvector

best at · OLTP, Geo, Search

DatomicImmutable Datalog database from Nubank where every fact is timestamped and queries run in the app process.
PostgreSQLThe extensible, standards-first open-source relational database.
overview
Primary model
Relational
Relational
Also supports
Graph
Document, Spatial
Type
Database engine
Database engine
Status
Active
Active
Developer
Nubank (Cognitect)
PostgreSQL Global Development Group
First release
2012
1996
Latest version
1.0.7745 (Oct 16, 2026)
18.6 (Aug 13, 2026)
License
Open source (permissive)Apache-2.0 (binaries only; source not published)
Open source (permissive)PostgreSQL License
Free tier
✓
✓
popularity
WhichDB Score
14.9
93.2
Rank
#225
#1
GitHub stars
–
22.6K
Stack Overflow questions
436
178.8K
scale & guarantees
Comfortable data size
Medium (≤ 10 TB)
Medium (≤ 10 TB)
Horizontal scaling
None
Addon
Multi-region
None
Read replicas
ACID
Full
Full
Consistency
Strong
Strong
Schema
Flexible
Strict
Architecture
Distributed, Shared storage
Single node, Primary replica, Client server
deployment
Self-hosted
✓
✓
Vendor-managed cloud
—
—
Serverless
—
—
Embedded
✓
—
Edge
—
—
Clouds
AWS
AWS, Google Cloud, Azure, Oracle Cloud, IBM Cloud, Alibaba Cloud
capabilities
Transactions
✓
✓
Joins
✓
✓
Secondary indexes
✓
✓
Full-text search
✓
✓
Vector search
—
✓
Geospatial
—
✓
JSON
—
✓
Change data capture
✓
✓
Triggers
—
✓
Stored procedures
—
✓
Materialized views
—
✓
TTL / expiry
—
—
Pub/Sub
—
✓
Columnar storage
—
—
In-memory
—
—
Durable persistence
✓
✓
Compression
—
✓
Encryption at rest
—
—
Role-based access
—
✓
Time travel
✓
—
Branching
—
—
Online schema changes
—
✓
Streaming ingest
—
—
Offline sync
—
—
Runs in WebAssembly
—
—
interfaces
Query languages
Datalog, Pull API
SQL, PL/pgSQL
Client languages
Clojure, Java
C, Java, Python, JavaScript, Go, Rust, C#, Ruby
Best for
OLTP, Event sourcing, Ledger, Knowledge graph
OLTP, Geo, Search, Content
Add more to this comparisonNot sure either fits? Try smart match

Datomic vs PostgreSQL: FAQ

What is the difference between Datomic and PostgreSQL?

Datomic: Immutable Datalog database from Nubank where every fact is timestamped and queries run in the app process. PostgreSQL: The extensible, standards-first open-source relational database. Horizontal scaling is none in Datomic and addon in PostgreSQL. Only Datomic has time travel. Only PostgreSQL has vector search, geospatial, json, triggers, stored procedures.

When should I choose Datomic over PostgreSQL?

Choose Datomic for financial and banking domain models needing auditability; systems that must answer what was known at a given time; and complex domain graphs in Clojure services. Choose PostgreSQL for general-purpose application backend, SaaS multi-tenant data and geospatial applications with PostGIS.

Is Datomic or PostgreSQL more popular?

PostgreSQL ranks #1 on the WhichDB Score (93.2/100) and Datomic ranks #225 (14.9/100). Popularity is not fit: check the requirements that matter for your project.

Are Datomic and PostgreSQL open source?

Yes. Datomic is open source. License: Apache-2.0 (binaries only; source not published). Yes. PostgreSQL is open source. License: PostgreSQL License.