What causes "Fetch direction must be FETCH_FORWARD" in prestodb/presto?

Pass ResultSet.FETCH_FORWARD explicitly, or do not call setFetchDirection at all

prestodb/presto · error · SQLException

Fetch direction must be FETCH_FORWARD

Error message

Fetch direction must be FETCH_FORWARD

What it means

setFetchDirection is a validation guard in PrestoResultSet: after checkOpen(), any direction other than ResultSet.FETCH_FORWARD is rejected with this SQLException, because Presto result sets can only be iterated forward.

Source

Thrown at presto-jdbc/src/main/java/com/facebook/presto/jdbc/PrestoResultSet.java:701

            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("relative");
    }

    @Override
    public boolean previous()
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("previous");
    }

    @Override
    public void setFetchDirection(int direction)
            throws SQLException
    {
        checkOpen();
        if (direction != FETCH_FORWARD) {
            throw new SQLException("Fetch direction must be FETCH_FORWARD");
        }
    }

    @Override
    public int getFetchDirection()
            throws SQLException
    {
        checkOpen();
        return FETCH_FORWARD;
    }

    @Override
    public void setFetchSize(int rows)
            throws SQLException
    {
        checkOpen();
        if (rows < 0) {
            throw new SQLException("Rows is negative");

View on GitHub (pinned to 55bb57d202)

Solutions

Pass ResultSet.FETCH_FORWARD explicitly, or do not call setFetchDirection at all
Set fetch direction only when the code detects a non-Presto JDBC driver
Guard the call in a try-catch if the setting is purely advisory for your use case

Example fix

// before
rs.setFetchDirection(ResultSet.FETCH_UNKNOWN);
// after
rs.setFetchDirection(ResultSet.FETCH_FORWARD);

Defensive patterns

Strategy: validation

Validate before calling

if (direction != ResultSet.FETCH_FORWARD) {
    throw new IllegalArgumentException("Presto supports only FETCH_FORWARD");
}
rs.setFetchDirection(direction);

Prevention

Always pass ResultSet.FETCH_FORWARD or omit the call
Skip setFetchDirection when the driver is Presto (check conn.getMetaData().getDatabaseProductName())
Do not apply shared JDBC tuning code blindly to Presto connections

When it happens

Trigger: Calling setFetchDirection(FETCH_REVERSE) or setFetchDirection(FETCH_UNKNOWN) on a PrestoResultSet or its Statement.

Common situations: Generic connection-pool or framework initialization code that sets FETCH_UNKNOWN by default; ported code from drivers that accept any fetch direction.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/1bddaf7cfe75a7fe. Report an issue: GitHub.