We may earn a commission if you buy through links on this page. It never changes a score or a ranking. How we make money
It's a split decision.
Choose Apache Cassandra for workloads that need a distributed, masterless database, linear scalability, and replication across data centers. Choose PostgreSQL for an open-source object-relational database with official documentation and community learning resources. Both can be self-hosted and have no software purchase price. Your choice affects how you model data and operate the database; verify driver support and hosting costs against your application before committing.
01Side by side
| Apache Cassandra | PostgreSQL | |
|---|---|---|
| Pricing model | Free to download and self-host; no published billing | Free of charge; no paid plans |
| Free tier | Open-source software; no paid tier listed | Free software; no published seat or usage limits |
| Open source and licence | Open source; Apache License 2.0 | Open source; OSI-approved PostgreSQL License |
| Self-hosting | Self-host on commodity hardware or cloud infrastructure | Self-hostable open-source database server |
| Integrations | Community ecosystem; talks mention Kafka and object storage | Homepage does not list specific integrations |
| Deployment model | On-premises or cloud; replication across data centers | Self-hostable; deployment options not detailed |
| Documentation and learning | Cassandra 5.0 Quickstart and community talks | Official documentation and community learning resources |
| Scaling and availability | Masterless; linear scalability and multi-data-center replication | Homepage highlights reliability and performance |
Apache Cassandra Choose Apache Cassandra if
- Choose Apache Cassandra if you need a distributed, masterless architecture.
- Choose Apache Cassandra if you need replication across data centers.
- Choose Apache Cassandra if linear throughput scaling is a key requirement.
PostgreSQL Choose PostgreSQL if
- Choose PostgreSQL if your application fits an object-relational database.
- Choose PostgreSQL if official documentation and community learning resources matter.
- Choose PostgreSQL if you want an open-source database with no paid plans.
02Pricing at real usage
Apache Cassandra is free to download and self-host under the Apache License 2.0. The pricing information lists no monthly or annual software charge. PostgreSQL is also free of charge, has no paid plans, and uses the OSI-approved PostgreSQL License; its pricing information lists no published seat or usage limits.
Neither project lists a paid software tier whose bill rises with seats, queries, or data volume. For a self-hosted deployment, budget for the infrastructure and operational work your chosen deployment requires; the projects publish no infrastructure price. This is not a comparison of managed database services, which may charge separately. Before estimating production cost, size the required capacity and ask any hosting provider about compute, storage, network transfer, backups, and support charges. The software price alone does not determine the total cost.
03API, SDKs and integration
Apache Cassandra is a distributed NoSQL database; PostgreSQL is an object-relational database. Those are different data models, so the choice should follow your application's data and query requirements. The official homepages do not specify a complete API, SDK, language, or CLI matrix. Check the relevant project documentation and driver compatibility for your languages and deployment before choosing; do not assume a driver or protocol version from the database category alone.
Cassandra's homepage links to a Cassandra 5.0 Quickstart and a third-party ecosystem of projects, tools, products, and services. Community talks listed there discuss Kafka and object storage integrations. PostgreSQL's homepage points to official documentation for installing and using the database, alongside community resources for learning and support. It does not list specific integrations. For either option, validate the drivers and operational tools your stack needs, including backup and export paths, against current documentation.
04Open source, self-hosting and lock-in
Both databases are open source and self-hostable. Cassandra is available under the Apache License 2.0; PostgreSQL uses the OSI-approved PostgreSQL License. Self-hosting gives teams control over where the database runs, but also means they take responsibility for operating it.
Cassandra's homepage describes deployments on commodity hardware, cloud infrastructure, and on-premises systems, with replication across data centers. Its community talks include topics on efficient export and backups, but those titles do not establish a particular export guarantee or workflow. PostgreSQL's homepage links to documentation and community resources but does not describe data export options. Check each database's current export, backup, and restore documentation before migration. Moving between a distributed NoSQL model and an object-relational model can require changes to data modeling and application queries; estimate that work with your actual schema and access patterns.
Questions people ask
Is Apache Cassandra or PostgreSQL better for high availability?
Cassandra is explicitly designed as a masterless distributed database with replication across data centers and no single points of failure. PostgreSQL's homepage highlights reliability but does not describe comparable distributed architecture. Choose based on your availability design and operational requirements, not on the database name alone.
Is Cassandra read- or write-optimized?
Cassandra's stated scaling feature covers both read and write throughput: the project says throughput increases linearly as machines are added. The vendor's homepage does not establish a universal read-versus-write advantage. Evaluate your workload, data model, and access patterns before deciding.
Which is best, MongoDB or PostgreSQL?
This comparison does not cover MongoDB. PostgreSQL is an open-source object-relational database with official documentation and community resources. To compare it with MongoDB, evaluate the data models, query needs, deployment options, and current costs for your application.
Is Apache Cassandra still used?
Cassandra's homepage describes the database as used by thousands of companies and lists community talks on operations, analytics, and integrations. That establishes ongoing project activity in the material dated here, but it does not quantify current production adoption or predict whether Cassandra fits a particular system.