apache/druid · error · IllegalArgumentException

Cartesian product too large; must have size at most…

Error message

Cartesian product too large; must have size at most Integer.MAX_VALUE

What it means

Druid's CartesianList builds a cartesian product of several lists and precomputes axis size products with IntMath.checkedMultiply. If the total product size would exceed Integer.MAX_VALUE, it throws IllegalArgumentException instead of overflowing silently.

Solutions

1. Reduce the number of elements in the input lists so the product fits under Integer.MAX_VALUE
2. Restructure the computation to iterate lazily/streaming instead of materializing the full cartesian product
3. Split the operation into batched smaller cartesian products

Example fix

// before
CartesianList.create(List.of(largeListA, largeListB, hugeListC));
// after
// limit or chunk axes first
if ((long)a.size()*b.size()*c.size() > Integer.MAX_VALUE) { /* batch */ }

long total = 1;
for (List<?> axis : axes) { total *= axis.size(); }
if (total > Integer.MAX_VALUE) throw new IllegalArgumentException("cartesian product too large");

try {
  list = CartesianList.create(axes);
} catch (IllegalArgumentException e) {
  if (e.getMessage() != null && e.getMessage().contains("Cartesian product too large")) {
    // batch the computation
  } else { throw e; }
}

When it happens

Trigger: Calling CartesianList.create(...) with axes whose sizes multiply to more than 2^31-1, e.g. many moderately sized lists combined.

Common situations: Expression/array expansion code producing join-like combinations of large arrays; generated test data or cross-join-style computations over many columns; accidental use of a giant nested-array input.

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• Already closed
• argument should be an identifier expression. Use array()…
• buffer for list is too small, was
• Cannot apply limit[ ] with offset[ ] due to overflow
• Cannot cast [ ] to [ ] (Types.InvalidCastException from…

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/464242a9096d35f0. Report an issue: GitHub.

Appendix: source

Thrown at processing/src/main/java/org/apache/druid/math/expr/CartesianList.java:68

        return Collections.emptyList();
      }
      axesBuilder.add(new ArrayList<>(list));
    }
    return new CartesianList<>(axesBuilder);
  }

  CartesianList(List<List<? extends E>> axes)
  {
    this.axes = axes;
    int[] axesSizeProduct = new int[axes.size() + 1];
    axesSizeProduct[axes.size()] = 1;
    try {
      for (int i = axes.size() - 1; i >= 0; i--) {
        axesSizeProduct[i] = IntMath.checkedMultiply(axesSizeProduct[i + 1], axes.get(i).size());
      }
    }
    catch (ArithmeticException e) {
      throw new IllegalArgumentException(
          "Cartesian product too large; must have size at most Integer.MAX_VALUE");
    }
    this.axesSizeProduct = axesSizeProduct;
  }

  private int getAxisIndexForProductIndex(int index, int axis)
  {
    return (index / axesSizeProduct[axis + 1]) % axes.get(axis).size();
  }

  @Override
  public int indexOf(Object o)
  {
    if (!(o instanceof List)) {
      return -1;
    }
    List<?> list = (List<?>) o;
    if (list.size() != axes.size()) {

View on GitHub (pinned to 9b90983fd2)