prestodb/presto · error · IllegalArgumentException

values length is less than positionCount

Error message

values length is less than positionCount

What it means

ByteArrayBlock's constructor validates that the values array contains at least positionCount readable bytes after accounting for arrayOffset. The library throws IllegalArgumentException when values.length - arrayOffset < positionCount because the block would otherwise be unable to serve positionCount positions without reading out of bounds. It is a data-consistency guard, not a runtime condition.

Source

Thrown at presto-common/src/main/java/com/facebook/presto/common/block/ByteArrayBlock.java:75

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

    ByteArrayBlock(int arrayOffset, int positionCount, boolean[] valueIsNull, byte[] 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. Adjust positionCount (or arrayOffset) so that values.length - arrayOffset >= positionCount
2. Trim the values array to exactly positionCount elements, e.g. Arrays.copyOfRange(values, arrayOffset, arrayOffset + positionCount)
3. Check the caller that computes positionCount (e.g. a deserializer or page decoder) for off-by-one or wrong-buffer errors
4. Verify you are constructing the block with the intended arrays — swapped or stale buffers from a previous call are a common cause

Example fix

// before
new ByteArrayBlock(100, Optional.empty(), new byte[50], null); // throws
// after
new ByteArrayBlock(50, Optional.empty(), new byte[50], null);

if (values.length - arrayOffset < positionCount) {
    throw new IllegalArgumentException(
        "values.length=" + values.length + " arrayOffset=" + arrayOffset +
        " < positionCount=" + positionCount);
}
ByteArrayBlock block = new ByteArrayBlock(positionCount, valueIsNull, values);

boolean canBuildByteArrayBlock(int positionCount, int arrayOffset, byte[] values) {
    return positionCount >= 0 && arrayOffset >= 0 && values.length - arrayOffset >= positionCount;
}

try {
    Block block = new ByteArrayBlock(positionCount, Optional.empty(), values, null);
} catch (IllegalArgumentException e) {
    log.error("Invalid block construction: %s", e.getMessage());
    throw new IllegalArgumentException("values array does not cover positionCount", e);
}

When it happens

Trigger: Calling new ByteArrayBlock(positionCount, Optional.empty(), values, valueIsNull) (or the arrayOffset overload) with a values array shorter than positionCount minus arrayOffset; wrapping a sliced/offset buffer without shrinking positionCount accordingly; building a block from a partially-filled serialization buffer.

Common situations: Custom Block implementations or serialization code miscomputing positionCount after array slicing; code upgraded across Presto versions where the ByteArrayBlock constructor signature changed (valueIsNull made Optional and length checks enforced); tests constructing blocks by hand.

Related errors

• isNull length is less than positionCount
• values length is less than positionCount
• values length is less than positionCount
• dictionarySourceIds must be the same
• blocks is empty

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/b65a907aaa0cb604. Report an issue: GitHub.