Fully transactional and multi-user, Derby is a mature engine and freely available under the Apache license and is actively maintained.
Empress Embedded Database runs on Linux, Unix, Microsoft Windows and real-time operating systems.
The initial product was soon joined by eXtremeDB High Availability (HA) for fault tolerant applications.
The product family now includes 64-bit and transaction logging editions, and the hybrid eXtremeDB Fusion, which combines in-memory and on-disk data storage.
As an open-source fork of InterBase, it is ACID compliant, supports triggers and stored procedures, and is available on Linux, OSX and Windows systems.
Embedded and Server mode, Clustering support, can run inside the Google App Engine.
Because the embedded engine is completely independent from MySQL, it lacks server components such as networking, object-level permissions, etc.
By eliminating the MySQL server overhead, InnoDB has a small footprint and is well-suited for embedding in applications which require high-performance and concurrency.
[6] HSQLDB is an opensource relational database management system with a BSD-like license that runs in the same Java Virtual Machine as the embedded application.
Client/Server includes a light-weight Servlet server, web admin and database browsing, and REST for python.
InterBase is an IoT Award-winning cross-platform, Unicode enabled SQL database platform able to be embedded within turn-key applications.
Ideal for both small-to-medium and large enterprises supporting hundreds of users and mobile application development.
Kùzu is an embeddable graph database management system that supports the Cypher (query language).
Kùzu achieves its performance largely through novel join algorithms that combine binary and worst-case optimal joins,[9] factorization[10] and vectorized query execution on a columnar storage layer,[10] as well as numerous compression and parallelization techniques common in modern database systems.
The library implements B+trees with multiversion concurrency control (MVCC), single-level store, Copy on write and provides full ACID transactions with no deadlocks.
An embedded zero maintenance version of the proprietary Mimer SQL relational database server is available.
Nonetheless, over recent years many well-known projects switched to using LMDB, because it outperform Berkeley DB in key scenarios on the ground of "less is more" design, as well due to the license changing.
It adds many features, including transactions,[14] backups,[15] snapshots,[16] bloom filters,[17] column families,[18] expiry,[19] custom merge operators,[20] more tunable compaction,[21] statistics collection,[22] and geospatial indexing.
[23] It is used as a storage engine inside of several other databases, including ArangoDB,[24] Ceph,[25] CockroachDB,[26] MongoRocks,[27] MyRocks,[28] Rocksandra,[29] TiKV.
In-memory database technology is used to achieve throughput of tens of thousands of transactions per second with response times measured in microseconds.
In case of system failure, applications can recover access to solid DB in less than a second without loss of data.
SQLite is a software library that implements a self-contained, server-less, zero-configuration, transactional SQL database engine.