... ResultSet holdability is HOLD_CURSOR_OVER_COMMIT. ...
And the postgresql comunity jdbc driver 9.4 documentation said:
"... There are a number of restrictions which will make the driver silently fall back to fetch the whole ResultSet ..."
And the statement must be created with a ResultSet holdability of CLOSE_CURSORS_AT_COMMIT - which is not documented. https://github.com/pgjdbc/pgjdbc/pull/1105 submitted to fix that.
The relevant code fragment from org.postgresql.jdbc.PgStatement.java is ...
// Enable cursor-based resultset if possible.
if (fetchSize > 0 && !wantsScrollableResultSet() && !connection.getAutoCommit()
&& !wantsHoldableResultSet()) {
flags |= QueryExecutor.QUERY_FORWARD_CURSOR;
}
And the fragment from org.postgresql.v3.QueryExecutorImpl.java ...
