apache/shardingsphere · error · UnsupportedOperationException

Unsupported Returning Expression

Error message

Unsupported Returning Expression

What it means

Thrown by OracleDMLStatementVisitor when a RETURNING clause projection cannot be mapped: createProjection handles ProjectionSegment, ComplexExpressionSegment, SimpleExpressionSegment, and generic ExpressionSegment, and throws UnsupportedOperationException('Unsupported Returning Expression') for anything else. It is a visitor coverage gap — the parsed AST node type has no projection mapping rule, not a user syntax error.

Source

Thrown at parser/sql/engine/dialect/oracle/src/main/java/org/apache/shardingsphere/sql/parser/engine/oracle/visitor/statement/type/OracleDMLStatementVisitor.java:1055

        }
        return new ReturningSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex(), projections);
    }
    
    private ProjectionSegment createReturningProjection(final ExprContext ctx) {
        ASTNode projection = visit(ctx);
        if (projection instanceof ProjectionSegment) {
            return (ProjectionSegment) projection;
        }
        if (projection instanceof ComplexExpressionSegment) {
            return (ProjectionSegment) createProjectionForComplexExpressionSegment(projection, null);
        }
        if (projection instanceof SimpleExpressionSegment) {
            return createExpressionProjectionSegment((ExpressionSegment) projection, null);
        }
        if (projection instanceof ExpressionSegment) {
            return (ProjectionSegment) createProjectionForExpressionSegment(projection, null);
        }
        throw new UnsupportedOperationException("Unsupported Returning Expression");
    }
    
    @Override
    public ASTNode visitSelectList(final SelectListContext ctx) {
        ProjectionsSegment result = new ProjectionsSegment(ctx.getStart().getStartIndex(), ctx.getStop().getStopIndex());
        Collection<ProjectionSegment> projections = new LinkedList<>();
        if (null != ctx.unqualifiedShorthand()) {
            projections.add(new ShorthandProjectionSegment(ctx.unqualifiedShorthand().getStart().getStartIndex(), ctx.unqualifiedShorthand().getStop().getStopIndex()));
            result.getProjections().addAll(projections);
            return result;
        }
        for (SelectProjectionContext each : ctx.selectProjection()) {
            projections.add((ProjectionSegment) visit(each));
        }
        result.getProjections().addAll(projections);
        return result;
    }
    

View on GitHub (pinned to e952770a21)

Solutions

1. Simplify the RETURNING list to plain columns or simple expressions
2. Move the complex computation out of RETURNING (e.g. return the column, compute in the app)
3. Upgrade ShardingSphere — visitor coverage for RETURNING expressions improves across releases
4. If extending the project, add a branch mapping the missing segment type in createProjection

Example fix

// before
INSERT INTO t (id) VALUES (seq.NEXTVAL) RETURNING id*2+1 INTO x

// after
INSERT INTO t (id) VALUES (seq.NEXTVAL) RETURNING id INTO x

try { parserEngine.parse(sql); }
catch (UnsupportedOperationException e) {
    // coverage gap, not bad syntax: simplify the RETURNING list and retry once with plain columns
    log.warn("Unsupported RETURNING expression, falling back to column-only RETURNING", e);
}

When it happens

Trigger: Oracle INSERT/UPDATE/DELETE ... RETURNING with an exotic expression whose visited AST node implements none of the four recognized segment interfaces: e.g. special PL/SQL-ish expressions, newly added segment types from newer grammars, or dialect-specific function segments.

Common situations: Using RETURNING with unusual expressions in Oracle-sharded tables; ShardingSphere version where the Oracle RETURNING grammar accepts an expression the visitor cannot classify; upgrading adds new segment types not yet wired into this chain.

Related errors

• Unsupported Expression
• Unhandled case
• Unsupported Complex Expression
• Unsupported Simple Expression
• 36

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/e01cfbdcd2bf002b. Report an issue: GitHub.