apache/shardingsphere · error · UnsupportedOperationException

Unsupported Complex Expression

Error message

Unsupported Complex Expression

What it means

Thrown by OracleDMLStatementVisitor.createProjectionForComplexExpressionSegment when a projection recognized as 'complex' is neither a FunctionSegment, CommonExpressionSegment, nor one of the XML function segments (XmlQueryAndExists/XmlPi/XmlSerialize/XmlElement). The UnsupportedOperationException marks the unhandled complex-expression shape — a coverage gap for specific complex expression node types.

Source

Thrown at parser/sql/engine/dialect/oracle/src/main/java/org/apache/shardingsphere/sql/parser/engine/oracle/visitor/statement/type/OracleDMLStatementVisitor.java:1150

    
    private ASTNode createProjectionForComplexExpressionSegment(final ASTNode projection, final AliasSegment alias) {
        if (projection instanceof FunctionSegment) {
            FunctionSegment segment = (FunctionSegment) projection;
            ExpressionProjectionSegment result = new ExpressionProjectionSegment(segment.getStartIndex(), segment.getStopIndex(), segment.getText(), segment);
            result.setAlias(alias);
            return result;
        }
        if (projection instanceof CommonExpressionSegment) {
            CommonExpressionSegment segment = (CommonExpressionSegment) projection;
            ExpressionProjectionSegment result = new ExpressionProjectionSegment(segment.getStartIndex(), segment.getStopIndex(), segment.getText(), segment);
            result.setAlias(alias);
            return result;
        }
        if (projection instanceof XmlQueryAndExistsFunctionSegment || projection instanceof XmlPiFunctionSegment || projection instanceof XmlSerializeFunctionSegment
                || projection instanceof XmlElementFunctionSegment) {
            return createExpressionProjectionSegment((ExpressionSegment) projection, alias);
        }
        throw new UnsupportedOperationException("Unsupported Complex Expression");
    }
    
    private ASTNode createProjectionForSimpleExpressionSegment(final ASTNode projection, final AliasSegment alias, final SelectProjectionExprClauseContext ctx) {
        if (projection instanceof SubqueryExpressionSegment) {
            SubqueryExpressionSegment subqueryExpressionSegment = (SubqueryExpressionSegment) projection;
            String text = ctx.start.getInputStream().getText(new Interval(subqueryExpressionSegment.getStartIndex(), subqueryExpressionSegment.getStopIndex()));
            SubqueryProjectionSegment result = new SubqueryProjectionSegment(((SubqueryExpressionSegment) projection).getSubquery(), text);
            result.setAlias(alias);
            return result;
        }
        if (projection instanceof LiteralExpressionSegment) {
            LiteralExpressionSegment column = (LiteralExpressionSegment) projection;
            ExpressionProjectionSegment result = null == alias
                    ? new ExpressionProjectionSegment(column.getStartIndex(), column.getStopIndex(), column.getText(), column)
                    : new ExpressionProjectionSegment(column.getStartIndex(), ctx.alias().stop.getStopIndex(), column.getText(), column);
            result.setAlias(alias);
            return result;
        }

View on GitHub (pinned to e952770a21)

Solutions

1. Flatten or alias the expression differently so it maps to FunctionSegment/CommonExpressionSegment
2. Move the XML/complex function out of the projection or wrap it as a plain expression
3. Upgrade ShardingSphere for wider complex-expression coverage
4. Report the exact expression as an upstream grammar/visitor gap

try { parserEngine.parse(sql); } catch (UnsupportedOperationException e) { /* mark statement unsupported; route around proxy parsing if possible */ }

When it happens

Trigger: Oracle SQL using a complex expression whose visited node is typed as something else (e.g. certain collection/multiset expressions reaching this method only via the alias path, or newly introduced segment types); the instanceof chain exhausts and throws.

Common situations: Heavy use of Oracle XML functions or nested function expressions in sharded SELECTs; version drift adding segment classes; queries generated by ORMs with unusual expression trees.

Related errors

• Unhandled case
• Unsupported Simple Expression
• Unsupported Expression
• Unsupported Returning Expression
• Projections not in simple select, table subquery, join subqu

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/0437dac29b70eb70. Report an issue: GitHub.