Re: ResultSet storing all rows with defaulftFetchSize to 5000

On Wed, Feb 7, 2018 at 1:00 PM, Jaime Soler <jaime.soler@gmail.com> wrote:

... 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 ...

    boolean usePortal = (flags & QueryExecutor.QUERY_FORWARD_CURSOR) != 0 && !noResults && !noMeta

        && fetchSize > 0 && !describeOnly;