apache/shardingsphere · error · UnsupportedOperationException

Unsupported expression: %s in page expression

Error message

Unsupported expression: %s in page expression

What it means

Thrown by ExpressionRowNumberValueSegment.getValueFromExpression when evaluating a row-number pagination expression at rewrite time: only ParameterMarkerExpressionSegment, BinaryOperationExpression, and LiteralExpressionSegment are evaluatable. Any other ExpressionSegment subclass triggers UnsupportedOperationException naming the segment class. This is runtime pagination-math evaluation (Oracle/rownum-style LIMIT/OFFSET folding), not initial parsing.

Source

Thrown at parser/sql/statement/core/src/main/java/org/apache/shardingsphere/sql/parser/statement/core/segment/dml/pagination/rownum/ExpressionRowNumberValueSegment.java:58

     *
     * @param params parameters
     * @return value
     */
    public Long getValue(final List<Object> params) {
        return getValueFromExpression(expressionSegment, params);
    }
    
    private Long getValueFromExpression(final ExpressionSegment expressionSegment, final List<Object> params) {
        if (expressionSegment instanceof ParameterMarkerExpressionSegment) {
            return null == params || params.isEmpty() ? 0L : Long.parseLong(params.get(((ParameterMarkerExpressionSegment) expressionSegment).getParameterMarkerIndex()).toString());
        }
        if (expressionSegment instanceof BinaryOperationExpression) {
            return getValueFromBinaryOperationExpression((BinaryOperationExpression) expressionSegment, params);
        }
        if (expressionSegment instanceof LiteralExpressionSegment) {
            return Long.parseLong(expressionSegment.getText());
        }
        throw new UnsupportedOperationException(String.format("Unsupported expression: %s in page expression", expressionSegment.getClass().getName()));
    }
    
    private Long getValueFromBinaryOperationExpression(final BinaryOperationExpression binaryOperationExpression, final List<Object> params) {
        String operator = binaryOperationExpression.getOperator();
        Long leftValue = getValueFromExpression(binaryOperationExpression.getLeft(), params);
        Long rightValue = getValueFromExpression(binaryOperationExpression.getRight(), params);
        switch (operator) {
            case "+":
                return leftValue + rightValue;
            case "-":
                return leftValue - rightValue;
            case "*":
                return leftValue * rightValue;
            case "/":
                return leftValue / rightValue;
            default:
                throw new UnsupportedOperationException(String.format("Unsupported operator: %s in page expression", operator));
        }

View on GitHub (pinned to e952770a21)

Solutions

  1. Rewrite the pagination expression using literals, parameter markers, or +/-/*// over them
  2. Compute the bound in application code and pass it as a single parameter marker
  3. Avoid functions or exotic expressions inside ROWNUM/row-number pagination predicates
  4. If the segment type is genuinely evaluatable, extend getValueFromExpression in a fork/PR

Example fix

// before
SELECT * FROM t WHERE ROWNUM <= CEIL(10/2)

// after
SELECT * FROM t WHERE ROWNUM <= 5
Defensive patterns

Strategy: validation

Validate before calling

// Fold pagination bounds in app code; only literals/markers/+,-,*,/ survive rewrite
long bound = pageSize + offset;
String sql = "SELECT * FROM (SELECT t.*, ROWNUM rn FROM t) WHERE rn <= " + bound;

Try / catch

try { rewriteEngine.rewrite(query); } catch (UnsupportedOperationException e) { /* reissue with folded literal bound */ }

Prevention

When it happens

Trigger: A rownum-based pagination predicate whose value expression is, e.g., a function call (LEVEL, sequence, SYSDATE), a case expression, or any segment type beyond the three handled — getValueFromExpression is called during SQL rewrite to fold the numeric value and cannot resolve it.

Common situations: ROWNUM <= ? + 10 works (binary op), but ROWNUM <= some_func(1) or nested function expressions fail; upgrades that change how an expression is visited (reclassified segments); dialect migrations bringing non-numeric-friendly pagination expressions.

Related errors

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/9b3cbe4b0bdacdea. Report an issue: GitHub.