code: public LargeObject open(long oid, int mode, boolean commitOnClose) throws SQLException {
      if (conn.getAutoCommit()) {
        throw new PSQLException(GT.tr("Large Objects may not be used in auto-commit mode."),
            PSQLState.NO_ACTIVE_SQL_TRANSACTION);
      }
      return new LargeObject(fp, oid, mode, conn, commitOnClose);
    }
docs: This opens an existing large object, based on its OID.
  
  @param oid of large object
  @param mode mode of open
  @param commitOnClose commit the transaction when this LOB will be closed
  @return LargeObject instance providing access to the object
  @throws SQLException on error