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GH-1190: Reserve view slots for empty view vector values #1192

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GH-1190: Reserve view slots for empty view vector values #1192

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b2d7a6a
GH-1190: Reserve view slots for empty view vector values
goutamadwant Jun 18, 2026
f9d306b
GH-1190: Add view vector null boundary coverage
goutamadwant Jul 10, 2026
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3 changes: 2 additions & 1 deletion vector/src/main/java/org/apache/arrow/vector/BaseVariableWidthViewVector.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1405,7 +1405,8 @@ public final int getTotalValueLengthUpToIndex(int index) {
}

protected final void handleSafe(int index, int dataLength) {
final long targetCapacity = roundUpToMultipleOf16((long) index * ELEMENT_SIZE + dataLength);
// The view buffer stores one fixed-width view per value; payload bytes are allocated separately.
final long targetCapacity = roundUpToMultipleOf16(((long) index + 1) * ELEMENT_SIZE);

@mbutrovich mbutrovich Jul 8, 2026

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Correct. Reserves the full slot regardless of payload; ((long) index + 1) avoids overflow. roundUpToMultipleOf16 is a no-op here but fine to keep.

@goutamadwant goutamadwant Jul 10, 2026

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Thanks for reviewing @mbutrovich . I kept this code path unchanged since it reserves the full view slot regardless of payload size and the cast keeps the sizing expression safe before the multiplication. Let me know if there any other thoughts.

if (viewBuffer.capacity() < targetCapacity) {
reallocViewBuffer(targetCapacity);
}
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54 changes: 54 additions & 0 deletions vector/src/test/java/org/apache/arrow/vector/TestVariableWidthViewVector.java
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Expand Up @@ -540,6 +540,60 @@ public void testSizeOfViewBufferElements() {
}
}

@ParameterizedTest
@MethodSource({"vectorCreatorProvider"})
public void testSetSafeEmptyValueAtViewBufferBoundary(

@mbutrovich mbutrovich Jul 8, 2026 •
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Only covers the empty-value path. setNull and fillEmpties/setValueCount reach the same handleSafe(index, 0). Suggest adding tests for those.

setValueCount trailing gap (silent trigger, no empty string written)

@ParameterizedTest
@MethodSource({"vectorCreatorProvider"})
public void testSetValueCountFillsEmptiesAtViewBufferBoundary(
    Function<BufferAllocator, BaseVariableWidthViewVector> vectorCreator) {
  try (final BaseVariableWidthViewVector vector = vectorCreator.apply(allocator)) {
    vector.allocateNew();
    final int valueCapacity = vector.getValueCapacity();
    vector.setSafe(valueCapacity - 1, "x".getBytes(StandardCharsets.UTF_8));
    // Leaves index valueCapacity unset: fillEmpties -> handleSafe(_, 0) on a full buffer.
    vector.setValueCount(valueCapacity + 1);
    assertTrue(vector.getValueCapacity() > valueCapacity);
    assertTrue(vector.isNull(valueCapacity));
  }
}

setNull at the boundary

@ParameterizedTest
@MethodSource({"vectorCreatorProvider"})
public void testSetNullAtViewBufferBoundary(
    Function<BufferAllocator, BaseVariableWidthViewVector> vectorCreator) {
  try (final BaseVariableWidthViewVector vector = vectorCreator.apply(allocator)) {
    vector.allocateNew();
    final int valueCapacity = vector.getValueCapacity();
    for (int i = 0; i <= valueCapacity; i++) {
      vector.setNull(i);
    }
    vector.setValueCount(valueCapacity + 1);
    assertTrue(vector.getValueCapacity() > valueCapacity);
    assertTrue(vector.isNull(valueCapacity));
  }
}

@goutamadwant goutamadwant Jul 10, 2026

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@mbutrovich added coverage for both additional paths: setNull and setValueCount/fillEmpties at the view-buffer boundary. The production fix is unchanged and his just closes the missing regression coverage. Let me know. thanks!

Function<BufferAllocator, BaseVariableWidthViewVector> vectorCreator) {
try (final BaseVariableWidthViewVector vector = vectorCreator.apply(allocator)) {
final byte[] emptyValue = new byte[0];
vector.allocateNew();
final int valueCapacity = vector.getValueCapacity();

for (int i = 0; i <= valueCapacity; i++) {
vector.setSafe(i, emptyValue);
}

vector.setValueCount(valueCapacity + 1);
assertTrue(vector.getValueCapacity() > valueCapacity);
assertEquals(0, vector.getValueLength(valueCapacity));
assertArrayEquals(emptyValue, vector.get(valueCapacity));
}
}

@ParameterizedTest
@MethodSource({"vectorCreatorProvider"})
public void testSetValueCountFillsEmptiesAtViewBufferBoundary(
Function<BufferAllocator, BaseVariableWidthViewVector> vectorCreator) {
try (final BaseVariableWidthViewVector vector = vectorCreator.apply(allocator)) {
vector.allocateNew();
final int valueCapacity = vector.getValueCapacity();

vector.setSafe(valueCapacity - 1, "x".getBytes(StandardCharsets.UTF_8));
vector.setValueCount(valueCapacity + 1);

assertTrue(vector.getValueCapacity() > valueCapacity);
assertTrue(vector.isNull(valueCapacity));
}
}

@ParameterizedTest
@MethodSource({"vectorCreatorProvider"})
public void testSetNullAtViewBufferBoundary(
Function<BufferAllocator, BaseVariableWidthViewVector> vectorCreator) {
try (final BaseVariableWidthViewVector vector = vectorCreator.apply(allocator)) {
vector.allocateNew();
final int valueCapacity = vector.getValueCapacity();

for (int i = 0; i <= valueCapacity; i++) {
vector.setNull(i);
}
vector.setValueCount(valueCapacity + 1);

assertTrue(vector.getValueCapacity() > valueCapacity);
assertTrue(vector.isNull(valueCapacity));
}
}

@Test
public void testNullableVarType1() {

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