HSQLDB supports various storage types, offering flexibility in how data is stored and accessed. The different storage types supported by HSQLDB include :

In-Memory Tables : In-memory tables store data entirely in RAM, providing extremely fast read and write access. These tables are ideal for temporary data, caching, and operations where speed is critical. However, data in in-memory tables is not persistent and is lost when the database is shut down.

Cached Tables : Cached tables also store data in memory but use a cache file on disk to persist data between database sessions. Cached tables offer improved performance compared to disk-based tables while still providing persistence across database restarts. They are suitable for applications that require fast data access and moderate data durability.

Disk-Based Tables : Disk-based tables store data directly on disk, ensuring data durability and persistence even after the database is shut down. These tables are suitable for storing large datasets and long-term storage requirements. Disk-based tables offer slower access compared to in-memory and cached tables but provide better durability and reliability.
Text Tables : Text tables store data in plain text files, allowing easy import/export of data using standard text file formats (e.g., CSV). Text tables are suitable for simple data storage and exchange requirements, such as data migration, data interchange, and batch processing tasks.

Compressed Tables : HSQLDB supports compressed tables, which use compression techniques to reduce storage space and improve performance. Compressed tables are suitable for storing large datasets with limited disk space or bandwidth constraints. They offer similar performance characteristics to disk-based tables while consuming less storage space.