Open-source IBM Db2 alternatives

TiDB is a cloud-native, open-source distributed SQL database from PingCAP. The name's Ti stands for titanium, and it is built for high availability, strong consistency and the ability to scale out as data and traffic grow, while staying compatible with MySQL so existing applications and tools can connect with little change.

Distributed transactions use a two-phase commit protocol to keep ACID guarantees even across nodes, through network partitions or node failures. It scales horizontally by adding nodes or vertically by adding resources, without downtime, and its architecture separates compute from storage so each can be adjusted independently. Built-in Raft consensus keeps multiple replicas in sync and handles automated failover. Topics also mention HTAP workloads, analytics and native vector search.

TiDB is written in Go under the Apache-2.0 license. It can be deployed on your own infrastructure or consumed as a managed cloud service, and it suits teams that have outgrown a single MySQL server and want horizontal scale without sharding by hand.

PostgreSQL is a feature-rich object-relational database management system covering a large part of the SQL standard. Its feature set includes transactions, foreign keys, subqueries, triggers, and user-defined types and functions, and the distribution also contains C language bindings. This GitHub repository is only a mirror of the official git repository, written in C, and the metadata lists the license as Other.

The project does not use GitHub pull requests; contributors submit patches through the process described on the PostgreSQL wiki. Copyright and license terms are in the COPYRIGHT file, general documentation for each version is published on the project site, and build instructions explain how to compile the server from source. The latest releases of the software and related software are available from the PostgreSQL website. Many hosting providers offer managed PostgreSQL, but the project itself is software you install and operate.

YugabyteDB is a distributed SQL database that is compatible with PostgreSQL. It combines the relational features of traditional databases with the scale-out design of NoSQL systems, and is intended for cloud-native OLTP applications that need correct data and at least one of scalability, tolerance to failures or global distribution.

Its SQL layer, YSQL, reuses the PostgreSQL query layer and so supports most PostgreSQL features, including data types, stored procedures, triggers and extensions. Its transaction model follows the design of Google Spanner, using Raft consensus for replication and hybrid logical clocks for distributed ACID transactions, with snapshot, serializable and read committed isolation. Reads are strongly consistent by default and can be tuned to read from followers and replicas.

The database can be configured to withstand failures at the level of a disk, rack, node, zone, region or whole cloud, recovering on its own, and the topics mention multi-region, multi-cloud and Kubernetes deployments. The project is written mainly in C and C++, the repository lists its license as Other, and documentation covers architecture, roadmap and how to build applications.

OceanBase is a distributed relational database developed by Ant Group. It runs on a cluster of commodity servers and uses the Paxos protocol and a distributed architecture to provide high availability and scalability, without depending on a specific hardware architecture.

It is compatible with MySQL, which eases migration from MySQL databases, and supports hybrid transactional and analytical processing, so one engine can serve both OLTP and OLAP workloads. The project now describes itself as a unified, multi-model database for the AI era, with topics that include vector search and full-text search. Cloud-native operation is supported through a Kubernetes operator.

You can try it by deploying a stand-alone instance with an all-in-one package on Linux, starting a Docker container from images on Docker Hub, quay.io or ghcr.io, or running it on Kubernetes with ob-operator. OceanBase is written in C++ and licensed under Apache-2.0, with a developer guide for compiling the observer yourself.

MariaDB Server is an open-source relational database built by a global community with the MariaDB Foundation and MariaDB plc. It started out as a MySQL fork driven by the people who created MySQL, keeps a high degree of MySQL compatibility, and is described as a straightforward migration target for existing MySQL deployments.

Since then it has gained its own capabilities. A native VECTOR data type with approximate nearest-neighbour HNSW indexing has been available since version 11.8. Pluggable storage engines include InnoDB, Aria and MyRocks, plus ColumnStore (analytics), Spider (sharding) and S3 (archiving). Replication options include async, semi-sync and parallel modes using global transaction IDs, and Galera provides synchronous multi-primary clustering. On the SQL side it offers common table expressions, window functions, temporal tables with system versioning, sequences and a range of JSON functions.

It also offers an Oracle SQL mode with PL/SQL-style routines, GIS data types and full-text indexing, and security features such as role-based access control, pluggable authentication, data-at-rest encryption and TLS. MariaDB is written in C++ and licensed under GPL-2.0, and you run it on your own servers or in the cloud.