chroma-core/chroma · error · Error

MaxK k must be positive

Error message

MaxK k must be positive

What it means

MaxK's constructor requires k (the number of largest values to return) to be a positive integer. Any k <= 0 — including 0 — is rejected with a plain Error at construction time, before the query is serialized or sent.

Source

Thrown at clients/new-js/packages/chromadb/src/execution/expression/groupBy.ts:89

  public toJSON(): AggregateJSON {
    return {
      $min_k: {
        keys: this.keys.map((key) => key.name),
        k: this.k,
      },
    };
  }
}

export class MaxK extends Aggregate {
  constructor(public readonly keys: Key[], public readonly k: number) {
    super();
    if (keys.length === 0) {
      throw new Error("MaxK keys cannot be empty");
    }
    if (k <= 0) {
      throw new Error("MaxK k must be positive");
    }
  }

  public toJSON(): AggregateJSON {
    return {
      $max_k: {
        keys: this.keys.map((key) => key.name),
        k: this.k,
      },
    };
  }
}

export interface GroupByJSON {
  keys: string[];
  aggregate: AggregateJSON;
}

View on GitHub (pinned to aecdd12c8a)

Solutions

1. Pass a positive integer for k (k >= 1)
2. Clamp external input: Math.max(1, Math.floor(Number(topN) || 10))
3. Document that 'unlimited' is not expressible via k; pick an explicit bound instead

Example fix

// before
const agg = Aggregate.maxK(["score"], Number(req.query.top)); // top=0 -> Error

// after
const top = Math.max(1, Math.floor(Number(req.query.top) || 10));
const agg = Aggregate.maxK(["score"], top);

const top = Number(req.query.top);
if (!Number.isInteger(top) || top <= 0) {
  throw new Error(`top must be a positive integer, got ${req.query.top}`);
}
const agg = Aggregate.maxK(["score"], top);

const isPositiveInt = (v: unknown): v is number =>
  typeof v === "number" && Number.isInteger(v) && v > 0;

When it happens

Trigger: new MaxK([K.SCORE], 0); Aggregate.maxK(["score"], -3); or aggregate JSON { $max_k: { keys: ["score"], k: 0 } } parsed by Aggregate.from.

Common situations: k sourced from a request query parameter that defaults to 0 (e.g. ?top=0). Using 0 to mean 'all results' — in Chroma aggregates, k must be an explicit positive count. Fractional values from dividing counts (k: 10 / 3) also fail the integer positivity requirement downstream.

Related errors

• MinK k must be positive
• MaxK keys cannot be empty
• Aggregate input must be an Aggregate instance or object with
• MinK keys cannot be empty
• GroupBy keys cannot be empty

AI-assisted analysis of chroma-core/chroma@aecdd12c8a (2026-08-16). Data as JSON: /api/errors/d1c347e06a1fae4d. Report an issue: GitHub.