apache/shardingsphere · error · SQLFeatureNotSupportedException

relative

Error message

relative

What it means

relative(int rows) — moving the cursor a relative number of rows — is not supported by the SQL Federation ResultSet and always throws SQLFeatureNotSupportedException. The class whitelists only forward streaming methods; every relative/absolute scroll operation is rejected.

Source

Thrown at kernel/sql-federation/core/src/main/java/org/apache/shardingsphere/sqlfederation/resultset/AbstractUnsupportedOperationSQLFederationResultSet.java:85

    
    @Override
    public boolean first() throws SQLException {
        throw new SQLFeatureNotSupportedException("first");
    }
    
    @Override
    public boolean last() throws SQLException {
        throw new SQLFeatureNotSupportedException("last");
    }
    
    @Override
    public boolean absolute(final int row) throws SQLException {
        throw new SQLFeatureNotSupportedException("absolute");
    }
    
    @Override
    public boolean relative(final int rows) throws SQLException {
        throw new SQLFeatureNotSupportedException("relative");
    }
    
    @Override
    public int getRow() throws SQLException {
        throw new SQLFeatureNotSupportedException("getRow");
    }
    
    @Override
    public final void insertRow() throws SQLException {
        throw new SQLFeatureNotSupportedException("insertRow");
    }
    
    @Override
    public final void updateRow() throws SQLException {
        throw new SQLFeatureNotSupportedException("updateRow");
    }
    
    @Override

View on GitHub (pinned to e952770a21)

Solutions

1. Replace skip loops with SQL-level OFFSET/LIMIT windows
2. Emulate forward skips with a counted next() loop (for (int i=0;i<n && rs.next();i++))
3. Materialize the result set client-side if bidirectional relative movement is a hard requirement

Example fix

// before
rs.relative(10); // skip 10 rows

// after
for (int i = 0; i < 10 && rs.next(); i++) { /* skip */ }

if (rs.getType() == ResultSet.TYPE_FORWARD_ONLY) {
    // relative(n) unsupported: emulate with a counted next() loop
}

private boolean supportsRelative(final ResultSet rs) throws SQLException {
    return rs.getType() != ResultSet.TYPE_FORWARD_ONLY;
}

try {
    rs.relative(skip);
} catch (final SQLFeatureNotSupportedException e) {
    for (int i = 0; i < skip && rs.next(); i++) { /* skip forward */ }
}

When it happens

Trigger: Calling rs.relative(n) or rs.relative(-n) on a federated ResultSet, e.g. skip-ahead loops (relative(5)) or step-back loops written for scrollable cursors, executed against ShardingSphere with sql-federation enabled.

Common situations: Batch-processing code that skips N rows at a time; ported desktop-report tooling; ORM plugins that use relative() for windowed reads. Appears when such code runs against a federation-routed statement (cross-shard join,联邦查询) rather than a native driver connection.

Related errors

• afterLast
• first
• last
• absolute
• getCursorName

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/cfe53dba7dd7112f. Report an issue: GitHub.