What is HSQLDB limitations?

Question

Is there some limits for number of tables inside DB? Is there some limits for number of tables inside the schema?

Answer 1

Hope this helps

What are the limitations of the database (size of columns, number of tables, rows...)?

There is no imposed limitation. Number of columns, tables, indexes, size of columns and so on is limited only by the memory. For example, a user reported using a SELECT statement with 41 LEFT OUTER JOIN clauses on a huge database for a data mining application.

The current (2.0) size limit of an HSQLDB database is 16GB (by default) for all CACHED tables and 2GB for each TEXT table. If you use large MEMORY tables, memory is only limited by the allocated JVM memory, which can be several GB on modern machines and 64bit operating systems. Extensive tests have been made with the latest versions using the TestCacheSize and other test programs inserting millions of rows and resulting in data files of up to 16 GB and larger LOB sizes.

(source)

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An updated FAQ is available here. Specially look for section Reliability, Performance and Deployment.

The current size limit of an HSQLDB database is 8 TB for all CACHED tables and 256GB for each TEXT table...

Answer 2

There is no fixed limit on the number of tables or schemas. The definition of tables and schemas is held in memory. With the default Java memory allocation, thousands of schemas / tables can be defined.

The data in the tables can be held partly or entirely in memory, depending on the specified table type (MEMORY, CACHED or TEXT).