prestodb/presto · error · IllegalArgumentException

values length is less than positionCount

Error message

values length is less than positionCount

What it means

ShortArrayBlock's constructor checks that the backing short[] values array is at least arrayOffset + positionCount long. If values.length - arrayOffset < positionCount the block would read out of bounds, so the constructor rejects it with IllegalArgumentException. This protects all position reads against buffer overruns.

Source

Thrown at presto-common/src/main/java/com/facebook/presto/common/block/ShortArrayBlock.java:66

    public ShortArrayBlock(int positionCount, Optional<boolean[]> valueIsNull, short[] values)
    {
        this(0, positionCount, valueIsNull.orElse(null), values);
    }

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

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

        if (valueIsNull != null && valueIsNull.length - arrayOffset < 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

View on GitHub (pinned to 55bb57d202)

Solutions

1. Size the values array to at least arrayOffset + positionCount before construction.
2. Recompute positionCount as values.length - arrayOffset when intending to consume the whole array.
3. Check serialization/deserialization of the array for truncation.

Example fix

// before
short[] values = new short[positionCount - 1]; // too small
new ShortArrayBlock(arrayOffset, positionCount, values, valueIsNull);
// after
short[] values = new short[arrayOffset + positionCount];
new ShortArrayBlock(arrayOffset, positionCount, values, valueIsNull);

if (values.length - arrayOffset < positionCount) {
    throw new IllegalArgumentException("values too small: need " + (arrayOffset + positionCount) + ", have " + values.length);
}

boolean valuesFit(int arrayOffset, int positionCount, short[] values) {
    return values != null && values.length - arrayOffset >= positionCount;
}

try {
    block = new ShortArrayBlock(arrayOffset, positionCount, values, valueIsNull);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("values length is less than positionCount")) {
        values = Arrays.copyOf(values, arrayOffset + positionCount);
        block = new ShortArrayBlock(arrayOffset, positionCount, values, valueIsNull);
    } else {
        throw e;
    }
}

When it happens

Trigger: Constructing ShortArrayBlock where values.length - arrayOffset < positionCount, e.g. passing a truncated array or an oversized positionCount.

Common situations: Slicing code that splits an array by positions but sizes the new array too small, aggregation of multiple segments where lengths were summed incorrectly, or corrupted serialized input.

Related errors

• values length is less than positionCount
• Offset is not monotonically ascending. offsets[%s]=%s, offse
• A null map must have zero entries
• Number of fields in RowBlock must be positive
• position is not valid

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/c896f4343c18792d. Report an issue: GitHub.