Long string data type in H2 databases
You can use a CLOB Data Type. Take a look at their data type page:
CLOB is like VARCHAR, but intended for very large values. Unlike when using VARCHAR, large CLOB objects are not kept fully in-memory; instead, they are streamed. CLOB should be used for documents and texts with arbitrary size such as XML or HTML documents, text files, or memo fields of unlimited size.