prestodb/presto · error · IllegalArgumentException

isNull length is less than positionCount

Error message

isNull length is less than positionCount

What it means

The optional null bitmap must cover every position the block exposes: valueIsNull.length - positionOffset must be >= positionCount. The constructor throws IllegalArgumentException when the isNull array is shorter than the visible position range.

Source

Thrown at presto-common/src/main/java/com/facebook/presto/common/block/Int128ArrayBlock.java:79

    Int128ArrayBlock(int positionOffset, int positionCount, boolean[] valueIsNull, long[] values)
    {
        if (positionOffset < 0) {
            throw new IllegalArgumentException("positionOffset is negative");
        }
        this.positionOffset = positionOffset;
        if (positionCount < 0) {
            throw new IllegalArgumentException("positionCount is negative");
        }
        this.positionCount = positionCount;

        if (values.length - (positionOffset * 2) < positionCount * 2) {
            throw new IllegalArgumentException("values length is less than positionCount");
        }
        this.values = values;

        if (valueIsNull != null && valueIsNull.length - positionOffset < positionCount) {
            throw new IllegalArgumentException("isNull length is less than positionCount");
        }
        this.valueIsNull = valueIsNull;

        retainedSizeInBytes = INSTANCE_SIZE + sizeOf(valueIsNull) + sizeOf(values);
    }

    @Override
    public long getSizeInBytes()
    {
        return SIZE_IN_BYTES_PER_POSITION * (long) positionCount;
    }

    @Override
    public OptionalInt fixedSizeInBytesPerPosition()
    {
        return OptionalInt.of(SIZE_IN_BYTES_PER_POSITION);
    }

View on GitHub (pinned to 55bb57d202)

Solutions

1. Size valueIsNull as positionOffset + positionCount booleans, matching the values array's position coverage.
2. When creating a region, slice valueIsNull with the same offset logic used for positions (Arrays.copyOfRange(valueIsNull, offset, offset + count)).
3. Validate column-array lengths are equal before constructing the block.

Example fix

// before
boolean[] valueIsNull = new boolean[positionCount]; // ignores positionOffset
// after
boolean[] valueIsNull = new boolean[positionOffset + positionCount];

if (valueIsNull != null) {
    checkArgument(valueIsNull.length >= positionOffset + positionCount,
        "isNull array too small: need %d, got %d", positionOffset + positionCount, valueIsNull.length);
}

boolean nullBitmapCovers(boolean[] valueIsNull, int positionOffset, int positionCount) {
    return valueIsNull == null || valueIsNull.length >= positionOffset + positionCount;
}

try {
    block = new Int128ArrayBlock(offset, count, isNull, values);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("isNull length is less than positionCount")) {
        isNull = Arrays.copyOfRange(isNull, 0, offset + count); // pad and retry
        block = new Int128ArrayBlock(offset, count, isNull, values);
    } else { throw e; }
}

When it happens

Trigger: Passing a valueIsNull array sized for the original block but a positionOffset/positionCount describing a larger region; allocating valueIsNull as positionCount while using a nonzero positionOffset; passing an array trimmed by a previous compaction.

Common situations: Region/view construction where isNull was sliced but positions were not (or vice versa); page serialization round-trips that shrink the null channel; building blocks from columns of mismatched lengths.

Related errors

• positionOffset is negative
• positionCount is negative
• values length is less than positionCount
• isNull length is less than positionCount
• arrayOffset is negative

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c35ce4465bed6f6a. Report an issue: GitHub.