prestodb/presto · error · IllegalArgumentException

valueIsNull length is less than positionCount

Error message

valueIsNull length is less than positionCount

What it means

When a VariableWidthBlock carries nullability info, the valueIsNull boolean array must have one entry per position (valueIsNull.length - arrayOffset >= positionCount). A short array cannot record null-ness for all positions, so the constructor throws IllegalArgumentException.

Source

Thrown at presto-common/src/main/java/com/facebook/presto/common/block/VariableWidthBlock.java:90

        }
        this.arrayOffset = arrayOffset;
        if (positionCount < 0) {
            throw new IllegalArgumentException("positionCount is negative");
        }
        this.positionCount = positionCount;

        if (slice == null) {
            throw new IllegalArgumentException("slice is null");
        }
        this.slice = slice;

        if (offsets.length - arrayOffset < (positionCount + 1)) {
            throw new IllegalArgumentException("offsets length is less than positionCount");
        }
        this.offsets = offsets;

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

        sizeInBytes = offsets[arrayOffset + positionCount] - offsets[arrayOffset] + ((Integer.BYTES + Byte.BYTES) * (long) positionCount);
        retainedSizeInBytes = INSTANCE_SIZE + slice.getRetainedSize() + sizeOf(valueIsNull) + sizeOf(offsets);
    }

    @Override
    public final int getPositionOffset(int position)
    {
        return offsets[position + arrayOffset];
    }

    @Override
    public int getSliceLength(int position)
    {
        checkReadablePosition(position);
        return getSliceLengthUnchecked(position + arrayOffset);

View on GitHub (pinned to 55bb57d202)

Solutions

1. Size valueIsNull to at least arrayOffset + positionCount entries before construction.
2. Pass null only when the block genuinely has no null values; otherwise keep the array aligned with positionCount.
3. Audit the page-reading path for null-vector/data misalignment.

Example fix

// before
boolean[] valueIsNull = new boolean[positions - 1]; // too short
new VariableWidthBlock(0, positions, slice, offsets, valueIsNull);
// after
boolean[] valueIsNull = new boolean[positions];
new VariableWidthBlock(0, positions, slice, offsets, valueIsNull);

checkState(valueIsNull == null || valueIsNull.length - arrayOffset >= positionCount,
    "valueIsNull too short for %s positions", positionCount);

try {
    new VariableWidthBlock(arrayOffset, positionCount, slice, offsets, valueIsNull);
} catch (IllegalArgumentException e) {
    // realign null vector with positionCount
}

When it happens

Trigger: Constructing VariableWidthBlock with a non-null valueIsNull array shorter than arrayOffset + positionCount; e.g. reusing a null vector from a different-sized block or from a page read with mismatched chunk sizes.

Common situations: Column-reader code misaligning definition/null levels with data values; hand-written blocks in tests or connectors where valueIsNull was sized without the null count.

Related errors

• 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
• position is not valid

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/7b70ee69fe8dc4b1. Report an issue: GitHub.