apache/shardingsphere · warning · SQLFeatureNotSupportedException

isLast

Error message

isLast

What it means

The federation result set deliberately does not implement cursor-positioning methods; isLast() throws SQLFeatureNotSupportedException with the method name. AbstractUnsupportedOperationSQLFederationResultSet marks JDBC capabilities that the Calcite-backed federation result set does not support, so drivers or code that probe isLast() fail loudly instead of getting wrong answers.

Source

Thrown at kernel/sql-federation/core/src/main/java/org/apache/shardingsphere/sqlfederation/resultset/AbstractUnsupportedOperationSQLFederationResultSet.java:55

    
    @Override
    public boolean isBeforeFirst() throws SQLException {
        throw new SQLFeatureNotSupportedException("isBeforeFirst");
    }
    
    @Override
    public boolean isAfterLast() throws SQLException {
        throw new SQLFeatureNotSupportedException("isAfterLast");
    }
    
    @Override
    public boolean isFirst() throws SQLException {
        throw new SQLFeatureNotSupportedException("isFirst");
    }
    
    @Override
    public boolean isLast() throws SQLException {
        throw new SQLFeatureNotSupportedException("isLast");
    }
    
    @Override
    public void beforeFirst() throws SQLException {
        throw new SQLFeatureNotSupportedException("beforeFirst");
    }
    
    @Override
    public void afterLast() throws SQLException {
        throw new SQLFeatureNotSupportedException("afterLast");
    }
    
    @Override
    public boolean first() throws SQLException {
        throw new SQLFeatureNotSupportedException("first");
    }
    
    @Override

View on GitHub (pinned to e952770a21)

Solutions

  1. Avoid isLast() on ShardingSphere result sets; track row positions yourself while iterating with next().
  2. If the row count is needed, execute a COUNT query or fetch all rows into a list first.
  3. Disable federation for the query so a driver result set with full capabilities is returned.
  4. Configure ORMs to limit/offset via SQL rather than result-set positioning.

Example fix

// before
while (rs.next()) { if (rs.isLast()) { ... } }
// after
List<Row> rows = fetchAll(rs);  // iterate rs.next() and collect
if (!rows.isEmpty()) { handleLast(rows.get(rows.size() - 1)); }
Defensive patterns

Strategy: validation

Validate before calling

if (rs.getType() == ResultSet.TYPE_FORWARD_ONLY) {
    // do not call isLast()/isFirst(); count rows while iterating
}

Try / catch

try {
    boolean last = rs.isLast();
} catch (final SQLFeatureNotSupportedException ex) {
    // fall back to manual row tracking
}

Prevention

When it happens

Trigger: Application or ORM code calls ResultSet.isLast() on a result set produced by a federated query (federation enabled and the query executed through SQLFederationExecutor).

Common situations: OR frameworks and reporting tools that call isLast() for pagination/iteration logic; custom JDBC wrappers that always probe result-set capabilities; code migrated from non-federated paths where the underlying driver supported isLast().

Related errors

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/d1bc772e49b64743. Report an issue: GitHub.