dgraph-io/dgraph · error

Division by zero.

Error message

Division by zero.

What it means

Static zero-divisor check: when evaluating a binary operator, if the top-of-stack (right) operand is a constant equal to 0 and the operator is '/', '%' (or zero is invalid for ceil/sqrt/u- contexts), the parser rejects the query with 'Division by zero.'. Note the trailing period distinguishes it from the unary-branch variant.

Source

Thrown at dql/math.go:136

			}
		}
		topOp.Child = []*MathTree{topVal}

	case isTernary(topOp.Fn):
		if valueStack.size() < 3 {
			return errors.Errorf("Invalid Math expression. Expected 3 operands")
		}
		topVal1 := valueStack.popAssert()
		topVal2 := valueStack.popAssert()
		topVal3 := valueStack.popAssert()
		topOp.Child = []*MathTree{topVal3, topVal2, topVal1}

	default:
		if valueStack.size() < 2 {
			return errors.Errorf("Invalid Math expression. Expected 2 operands")
		}
		if isZero(topOp.Fn, valueStack.peek().Const) {
			return errors.Errorf("Division by zero.")
		}
		topVal1 := valueStack.popAssert()
		topVal2 := valueStack.popAssert()
		topOp.Child = []*MathTree{topVal2, topVal1}

	}
	// Push the new value (tree) into the valueStack.
	valueStack.push(topOp)
	return nil
}

func isMathFunc(f string) bool {
	// While adding an op, also add it to the corresponding function type.
	return f == "*" || f == "%" || f == "+" || f == "-" || f == "/" ||
		f == "exp" || f == "ln" || f == "cond" ||
		f == "<" || f == ">" || f == ">=" || f == "<=" ||
		f == "==" || f == "!=" ||
		f == "min" || f == "max" || f == "sqrt" ||

View on GitHub (pinned to 759e242be6)

Solutions

1. Use cond to guard: math(cond(d == 0, 0, a / d)) — but since this fires on constants, replace the constant 0 with a nonzero value.
2. Replace the zero constant divisor with a real variable or 1.
3. Precompute the divisor as a variable and filter zero values before the math block.
4. Review templating that injects numeric divisors to ensure 0 can never be emitted.

Example fix

// before
total as math(sum / 0)
// after
avg as math(cond(cnt == 0, 0, sum / cnt))

function assertNoZeroDivisor(expr) {
  if (/\/\s*0+(\.0+)?\b/.test(expr) || /%\s*0+(\.0+)?\b/.test(expr)) {
    throw new Error('math expression divides by constant zero');
  }
}
assertNoZeroDivisor('sum / 0');

try {
  return await dgraph.query(query);
} catch (err) {
  if (/Division by zero\.$/.test(String(err))) {
    throw new Error('Constant zero divisor found; use a nonzero constant or a guarded variable');
  }
  throw err;
}

When it happens

Trigger: math(a / 0), math(a % 0), or the right-hand operand is a zero constant produced by a parsed numeric literal, e.g. math(a / 0.0) or math(a / (1 - 1)).

Common situations: Template-generated queries where a variable interpolated to 0; hardcoded placeholder divisor never replaced; computing a constant sub-expression that evaluates to zero like math(count / (len - len)) style constructs.

Related errors

• Division by zero
• Division by zero
• Invalid Math expression
• Invalid math statement. Expected 1 operands
• Invalid Math expression. Expected 3 operands

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/722c28b7b2caf184. Report an issue: GitHub.