dgraph-io/dgraph · error

Unknown math function: %v

Error message

Unknown math function: %v

What it means

An identifier followed by '(' was found inside a math expression, so the parser treats it as a math function call, but the name is not in the known math function set (+,-,*,/,%,exp,ln,cond,comparisons,min,max,sqrt,pow,logbase,floor,ceil,since,dot). The parser rejects the unknown function name.

Source

Thrown at dql/math.go:228

					child, again, err = parseMathFunc(gq, it, again)
					if err != nil {
						return nil, false, err
					}
					valueStack.push(child)
					if !again {
						break
					}
				}
			}
		case item.Typ == itemName: // Value.
			peekIt, err := it.Peek(1)
			if err != nil {
				return nil, false, err
			}
			if peekIt[0].Typ == itemLeftRound {
				again := false
				if !isMathFunc(item.Val) {
					return nil, false, errors.Errorf("Unknown math function: %v", item.Val)
				}
				var child *MathTree
				for {
					child, again, err = parseMathFunc(gq, it, again)
					if err != nil {
						return nil, false, err
					}
					valueStack.push(child)
					if !again {
						break
					}
				}
				continue
			}
			// We will try to parse the constant as an Int first, if that fails we move to float
			child := &MathTree{}
			i, err := strconv.ParseInt(item.Val, 10, 64)
			if err != nil {

View on GitHub (pinned to 759e242be6)

Solutions

  1. Check the function name against the supported list: exp, ln, sqrt, floor, ceil, since, cond, min, max, pow, logbase, dot, and arithmetic/comparison operators.
  2. Compute aggregates as value variables first (a as sum(val(x))) and use the variable inside math, not the function call.
  3. Fix misspellings (squrt -> sqrt).
  4. There is no abs() in DQL math — use math(sqrt(v*v)) as a workaround.

Example fix

// before
total as math(abs(u))
// after
sq as math(sqrt(u * u))
Defensive patterns

Strategy: type-guard

Validate before calling

const MATH_FUNCS = new Set(['+','-','*','/','%','exp','ln','cond','<','>','>=','<=','==','!=','min','max','sqrt','pow','logbase','floor','ceil','since','dot']);
function assertKnownMathFuncs(expr) {
  const calls = expr.match(/([a-zA-Z_][\w.]*)\s*\(/g) || [];
  for (const c of calls) {
    const name = c.replace(/[\s(]/g, '');
    if (!MATH_FUNCS.has(name)) throw new Error(`Unknown math function: ${name}`);
  }
}

Type guard

const isMathFunc = (name) =>
  ['+','-','*','/','%','exp','ln','cond','<','>','>=','<=','==','!=',
   'min','max','sqrt','pow','logbase','floor','ceil','since','dot'].includes(name);

Try / catch

try {
  return await dgraph.query(query);
} catch (err) {
  if (/Unknown math function/.test(String(err))) {
    const fn = String(err).match(/Unknown math function: (\S+)/)?.[1];
    throw new Error(`${fn} is not a DQL math function; compute aggregates as value variables instead`);
  }
  throw err;
}

Prevention

When it happens

Trigger: Calling non-math functions inside math(), e.g. math(len(a)) or math(count(u)) — len/count are aggregate roots, not math funcs; typos like math(squrt(x)); using GraphQL-style functions in DQL math.

Common situations: Trying to nest aggregate functions inside math instead of using value variables; misspelling sqrt/floor/ceil; expecting SQL functions (ABS, ROUND) to exist — DQL uses abs-free patterns like sqrt(x*x) or floor/ceil only.

Related errors

AI-assisted analysis of dgraph-io/dgraph@759e242be6 (2026-09-01). Data as JSON: /api/errors/e67b4cf7b1a74d82. Report an issue: GitHub.