How much data can a java database DB store?
Here is the FAQ
What is the database size limit? A: Java DB stores each base table and each index in one file, so data size limitation is a file size limitation for the JVM and the OS on which it runs. Derby is encoded against 64-bit Java interfaces to access these files, so the maximum table size is approximately 2 * 64. The number of tables is limited to 64-bit table identifiers, for an approximate limit of 2 * 64 common tables. In practice, system resources, such as disk space, are a more likely source of size restrictions. Java DB is tested in a database using more than 350 GB of raw disk space with tables containing more than 500 million tuples.