eXtremeDB vs VoltDB

eXtremeDB is an in-memory database system designed for embedded devices and applications. It can combine in-memory and persistent storage within one database system. Interfaces include native APIs, REST, SQL, ODBC, and JDBC, with language APIs for C/C++, Java, Python, C#, Go, and Rust. For time-series data, a sequence type provides columnar storage. Distributed options include High Availability, Cluster, and Active Replication Fabric for replication across IoT tiers. Network communications can use TLS/SSL with OpenSSL or wolfSSL. Technical specifications list maximum database sizes of 4 GB on 32-bit architectures and 18.4 exabytes on 64-bit architectures. eXtremeDB supports Android, iOS, Linux, macOS, and Windows, and can be self-hosted. Evaluation downloads are listed for Linux, macOS, and Windows; custom trial packages can be requested for other platforms. McObject offers annual engineering support contracts that include software updates and a 50 percent discount on major upgrades. Commercial licensing is paid, with pricing available on request, and a 60-day trial is listed.

VoltDB is a distributed, in-memory database and real-time decisioning layer for data processing, stream ingestion, business logic, and AI integration. Its database partitions data and stored procedures so queries can run in parallel while maintaining ACID consistency. Volt Active Data says Volt is built to move from ingest to action in under 10 milliseconds. Clusters scale by adding nodes, with partitioning automated from the schema. Volt connects directly to Kafka or CDC streams and can expose decisions through SQL, REST, or Kafka topics. It supports on-premises, cloud Kubernetes or VM-based, and hybrid deployments. Production databases support Debian 12.11 or later, RHEL 8.8 or later, Rocky Linux 8.8 or later, and Ubuntu 20.04, 22.04, or 24.04; macOS 13 or later is supported for development. Enterprise Edition provides command logging, locally replicated partitions, and wide-area database replication. Authentication, role-based authorization, and TLS/SSL or Kerberos communications are available, but security is disabled by default. The free Developer Edition is not intended for production workloads. A free 30-day trial is listed for Confluent users; production pricing is on request.