HSQLDB vs Perst

HSQLDB is a Java-based relational database engine for embedded or server use, with both in-memory and disk-based tables. It supports SQL:2023 core features and many optional features, plus lock-based and MVCC transaction models; the engine is fully multithreaded. Listed capabilities include JSON constructor functions, CSV loading and unloading, temporal system-versioned tables, row-level access control, and log-based replica synchronization. It includes a command-line SQL tool and simple GUI query tools. The latest official release listed is version 2.7.4, compatible with JDK 8 and above, and packages include Java 11 module jars as well as Java 8 jars for HSQLDB and SQL Tool. HSQLDB is self-hosted, with high availability, read replicas, and JSON data support listed. Its default combined limit for CACHED tables is 8TB, extendable to 256TB with a connection property; each TEXT table is limited to 256GB, and memory tables depend on available memory. The software is free to use in commercial products when license terms are met; its licenses are based on the new BSD License. The HSQLDB plan is free. A Developer subscription is $100 a year; Premier Corporate is $2,500 a year at the base level. Support options include community channels and paid commercial support.

Perst has no write-up on Specifiction yet; its figures are above.