setFetchSize is defined there: https://github.com/pgjdbc/pgjdbc/blob/master/org/postgresql/jdbc2/AbstractJdbc2Statement.java but i havent checked if this value is really used for something. But probably not because its OOM here if result set is over 30k rows.
pgsql-jdbc by date:
Соглашаюсь с условиями обработки персональных данных